
VSC8662 Datasheet
Dual Port 10/100/1000BASE-T PHY and 100BASE-

FX/1000BASE-X SerDes with Recovered Clock Outputs

<» Microsemi

a AQ Microcuip company
�

VMDS-10312. 4.3 4/19

Microsemi Headquarters
One Enterprise, Aliso Viejo,
CA 92656 USA
Within the USA: +1 (800) 713-4113 
Outside the USA: +1 (949) 380-6100
Sales: +1 (949) 380-6136
Fax: +1 (949) 215-4996
Email: sales.support@microsemi.com
www.microsemi.com

©2019 Microsemi, a wholly owned 
subsidiary of Microchip Technology Inc. All 
rights reserved. Microsemi and the 
Microsemi logo are registered trademarks 
of Microsemi Corporation. All other 
trademarks and service marks are the 
property of their respective owners. 

Microsemi makes no warranty, representation, or guarantee regarding the information contained herein or the suitability of 
its products and services for any particular purpose, nor does Microsemi assume any liability whatsoever arising out of the 
application or use of any product or circuit. The products sold hereunder and any other products sold by Microsemi have 
been subject to limited testing and should not be used in conjunction with mission-critical equipment or applications. Any 
performance specifications are believed to be reliable but are not verified, and Buyer must conduct and complete all 
performance and other testing of the products, alone and together with, or installed in, any end-products. Buyer shall not 
rely on any data and performance specifications or parameters provided by Microsemi. It is the Buyer’s responsibility to 
independently determine suitability of any products and to test and verify the same. The information provided by Microsemi 
hereunder is provided “as is, where is” and with all faults, and the entire risk associated with such information is entirely 
with the Buyer. Microsemi does not grant, explicitly or implicitly, to any party any patent rights, licenses, or any other IP 
rights, whether with regard to such information itself or anything described by such information. Information provided in this 
document is proprietary to Microsemi, and Microsemi reserves the right to make any changes to the information in this 
document or to any products and services at any time without notice.

About Microsemi
Microsemi, a wholly owned subsidiary of Microchip Technology Inc. (Nasdaq: MCHP), offers a comprehensive portfolio of 
semiconductor and system solutions for aerospace & defense, communications, data center and industrial markets. 
Products include high-performance and radiation-hardened analog mixed-signal integrated circuits, FPGAs, SoCs and 
ASICs; power management products; timing and synchronization devices and precise time solutions, setting the world's 
standard for time; voice processing devices; RF solutions; discrete components; enterprise storage and communication 
solutions, security technologies and scalable anti-tamper products; Ethernet solutions; Power-over-Ethernet ICs and 
midspans; as well as custom design capabilities and services. Learn more at www.microsemi.com.

<< Microsemi

a A\\MicrocHip company
�mailto:sales.support@microsemi.com
http://www.microsemi.com


VMDS-10312 VSC8662 Datasheet Revision 4.3 iii

Contents

1 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Revision 4.3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Revision 4.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3 Revision 4.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.4 Revision 4.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.5 Revision 2.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 Overview  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.1 Key Features  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Block Diagram  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3 Functional Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1 Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2 SerDes MAC Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.2.1 SerDes MAC  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2.2 SGMII MAC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.3 SerDes Media Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3.1 SerDes Media with PCS Auto-Negotiation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3.2 SerDes Pass-Through Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3.3.3 SGMII MAC-to-100BASE-FX Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3.4 Unidirectional Transport for Fiber Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.4 Advanced SerDes Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.4.1 SerDes Receiver Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.4.2 SerDes Transmitter Amplitude Control  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.4.3 SerDes Link Integrity Information  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

3.5 Cat5 Twisted Pair Media Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.5.1 Voltage-Mode Line Driver  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.5.2 Cat5 Auto-Negotiation and Parallel Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.5.3 Automatic Crossover and Polarity Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.5.4 Manual MDI/MDI-X Setting  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.5.5 Link Speed Downshift  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3.6 Automatic Media-Sense (AMS) Interface Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.7 Transformerless Ethernet  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.8 Ethernet Inline Powered Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.9 IEEE 802.3af PoE Support  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.10 ActiPHY Power Management  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.10.1 Low Power State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.10.2 Link Partner Wake-up State  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.10.3 Normal Operating State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.11 Media Recovered Clock Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.11.1 Clock Selection Settings  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.11.2 Clock Output Squelch  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.12 Fast Link Failure Indication  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.13 Serial Management Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.13.1 SMI Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3.13.2 SMI Interrupts  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.14 LED Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.14.1 LED Modes  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.14.2 Extended LED Modes  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.14.3 LED Behavior  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

<» Microsemi

a AQ Microcuip company
�

VMDS-10312 VSC8662 Datasheet Revision 4.3 iv

3.14.4 Serial LED Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.14.5 LED Port Swapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.15 Integrated Two-Wire Serial Multiplexer  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.15.1 Read/Write Access Using the Two-Wire Serial Mux  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.16 GPIO Pins  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.17 Testing Features  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

3.17.1 Ethernet Packet Generator (EPG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.17.2 CRC Counters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.17.3 Far-End Loopback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.17.4 Near-End Loopback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.17.5 Connector Loopback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.17.6 SerDes Loopbacks  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.17.7 VeriPHY Cable Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.17.8 IEEE 1149.1 JTAG Boundary Scan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.17.9 JTAG Instruction Codes  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.17.10 Boundary Scan Register Cell Order  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.17.11 IEEE 1149.6 AC-JTAG Boundary Scan Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

4 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.1 Registers  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

4.1.1 Reserved Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4.1.2 Reserved Bits  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

4.2 IEEE Standard and Main Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.2.1 Mode Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.2.2 Mode Status  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.2.3 Device Identification  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.2.4 Auto-Negotiation Advertisement  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.2.5 Link Partner Auto-Negotiation Capability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.2.6 Auto-Negotiation Expansion  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.2.7 Transmit Auto-Negotiation Next Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.2.8 Auto-Negotiation Link Partner Next Page Receive  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.2.9 1000BASE-T Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.2.10 1000BASE-T Status  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.2.11 1000BASE-T Status Extension 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.2.12 100BASE-TX Status Extension . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.2.13 1000BASE-T Status Extension 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.2.14 Bypass Control  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.2.15 Error Counter 1  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.2.16 Error Counter 2  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.2.17 Error Counter 3  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.2.18 Extended Control and Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
4.2.19 Extended PHY Control Set 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.2.20 Extended PHY Control Set 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.2.21 Interrupt Mask  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.2.22 Interrupt Status  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
4.2.23 MAC Interface Auto-Negotiation Control and Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
4.2.24 Device Auxiliary Control and Status  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
4.2.25 LED Mode Select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.2.26 LED Behavior  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

4.3 Extended Page Registers  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.3.1 Extended Page Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.3.2 SerDes Media Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.3.3 SerDes MAC/Media Control  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.3.4 CRC Good Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.3.5 SerDes Loopback and SIGDET Control  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.3.6 ActiPHY Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.3.7 PoE and Miscellaneous Functionality  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54



VMDS-10312 VSC8662 Datasheet Revision 4.3 v

4.3.8 SerDes MAC/Media Status  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
4.3.9 Ethernet Packet Generator Control 1  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.3.10 Ethernet Packet Generator Control 2  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

4.4 General-Purpose I/O Registers  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.4.1 Reserved GPIO Address Space  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.4.2 SIGDET vs. GPIO Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.4.3 GPIO Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.4.4 GPIO Output  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.4.5 GPIO Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.4.6 Fast Link Fail Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.4.7 Two-Wire Serial Mux Control 1  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.4.8 Two-Wire Serial Mux Control 2  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.4.9 Two-Wire Serial Mux Data Read/Write  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.4.10 Recovered Clock 1  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.4.11 Recovered Clock 2  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
4.4.12 LED Port Swapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

4.5 CMODE  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.5.1 CMODE Pins and Related Functions  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.5.2 Functions and Related CMODE Pins  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.5.3 CMODE Resistor Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

5 Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5.1 DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

5.1.1 VDDIO at 3.3 V  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5.1.2 VDDIO at 2.5 V  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5.1.3 VDDIO at 1.8 V  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
5.1.4 VDD33 at 3.3 V  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
5.1.5 DC Characteristics for MAC and SerDes Media Outputs  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.1.6 DC Characteristics for MAC and SerDes Media Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.1.7 LED Pins  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
5.1.8 JTAG Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

5.2 Current Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
5.3 AC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

5.3.1 Reference Clock Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
5.3.2 Clock Output  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
5.3.3 Recovered Clock Outputs  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
5.3.4 AC Characteristics for MAC and SerDes Media Outputs  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
5.3.5 AC Characteristics for MAC and SerDes Media Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
5.3.6 JTAG Interface  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
5.3.7 SMI Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.3.8 Device Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
5.3.9 Serial LEDs  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

5.4 Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
5.5 Stress Ratings  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

6 Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
6.1 Pin Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
6.2 Pin Identifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
6.3 Pins by Function  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

6.3.1 GPIO  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.3.2 JTAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.3.3 Miscellaneous Pins  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
6.3.4 Power Supply  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
6.3.5 SerDes MAC Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
6.3.6 SerDes Media Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
6.3.7 Serial Management Interface  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83



VMDS-10312 VSC8662 Datasheet Revision 4.3 vi

6.4 Twisted Pair Interface  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
6.5 Pins by Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.6 Pins by Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

7 Package Information  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
7.1 Package Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
7.2 Thermal Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
7.3 Moisture Sensitivity  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

8 Design Considerations  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
8.1 Required Device Configuration  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
8.2 Broadcast Writes  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
8.3 Enabling LED Blinking After Reset  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
8.4 100/1000BASE-T Amplitude Compensation  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
8.5 Increase 10BASE-T Performance  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
8.6 Performance Optimization for 100BASE-TX and 1000BASE-T Slave . . . . . . . . . . . . . . . . . . . . . . . . . . 97
8.7 Enable SGMII Version 1.8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
8.8 Disabling Recovered Clock Output  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

9 Ordering Information  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99



VMDS-10312 VSC8662 Datasheet Revision 4.3 vii

Figures

Figure 1 Typical Application  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Figure 2 VSC8662 Block Diagram  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Figure 3 SerDes MAC Interface  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Figure 4 SGMII MAC Interface  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Figure 5 Cat5 Media Interface  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 6 Automatic Media Sense Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 7 Inline Powered Ethernet Switch Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Figure 8 ActiPHY State Diagram  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 9 SMI Read Frame  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 10 SMI Write Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Figure 11 MDINTn Configured as an Open-Drain (Active-Low) Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 12 MDINTn Configured as an Open-Source (Active-High) Pin  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 13 Example of Using Two-Wire Serial Mux with SFP Control and Status . . . . . . . . . . . . . . . . . . . . . . 21
Figure 14 Two-Wire Serial Mux Read and Write Register Flow  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Figure 15 Far-End Loopback Diagram  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 16 Near-End Loopback Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 17 Connector Loopback Diagram  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Figure 18 SerDes Loopbacks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 19 Test Access Port and Boundary Scan Architecture Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Figure 20 Register Space Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 21 JTAG Interface Timing  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Figure 22 SMI Interface Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Figure 23 Reset Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Figure 24 Serial LED Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Figure 25 Pin Diagram, Top Left . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Figure 26 Pin Diagram, Top Right  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Figure 27 Package Drawing  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92



VMDS-10312 VSC8662 Datasheet Revision 4.3 viii

Tables

Table 1 Operating Mode vs. Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Table 2 Supported MDI Pair Combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Table 3 AMS Media Preferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Table 4 LED Mode and Function Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 5 Extended LED Mode and Function Summary  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Table 6 LED Serial Stream Order  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Table 7 LED Port Swapping Table  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Table 8 JTAG Device Identification Register Description  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Table 9 JTAG Interface Instruction Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Table 10 IEEE 802.3 Standard Registers  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 11 Main Registers  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Table 12 Mode Control, Address 0 (0x00) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Table 13 Mode Status, Address 1 (0x01)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 14 Identifier 1, Address 2 (0x02)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 15 Identifier 2, Address 3 (0x03)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 16 Device Auto-Negotiation Advertisement, Address 4 (0x04)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Table 17 Auto-Negotiation Link Partner Ability, Address 5 (0x05) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Table 18 Auto-Negotiation Expansion, Address 6 (0x06)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 19 Auto-Negotiation Next Page Transmit, Address 7 (0x07) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 20 Auto-Negotiation LP Next Page Receive, Address 8 (0x08)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 21 1000BASE-T Control, Address 9 (0x09) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 22 1000BASE-T Status, Address 10 (0x0A)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table 23 1000BASE-T Status Extension 1, Address 15 (0x0F)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Table 24 100BASE-TX Status Extension, Address 16 (0x10) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Table 25 1000BASE-T Status Extension 2, Address 17 (0x11)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Table 26 Bypass Control, Address 18 (0x12)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Table 27 Extended Control and Status, Address 19 (0x13)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Table 28 Extended Control and Status, Address 20 (0x14)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Table 29 Extended Control and Status, Address 21 (0x15)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Table 30 Extended Control and Status, Address 22 (0x16)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Table 31 Extended PHY Control 1, Address 23 (0x17) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Table 32 Extended PHY Control 2, Address 24 (0x18) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Table 33 Interrupt Mask, Address 25 (0x19) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Table 34 Interrupt Status, Address 26 (0x1A) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Table 35 MAC Auto-Negotiation Control and Status, Address 27 (0x1B)  . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Table 36 Auxiliary Control and Status, Address 28 (0x1C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Table 37 LED Mode Select, Address 29 (0x1D)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Table 38 LED Behavior, Address 30 (0x1E)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Table 39 Extended Registers Page Space  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Table 40 Extended Page Access, Address 31 (0x1F) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Table 41 SerDes Media Auto-Negotiation Control/Status, Address 16E (0x10)  . . . . . . . . . . . . . . . . . . . . . . 50
Table 42 SerDes MAC Control, Address 17E (0x11)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Table 43 CRC Good Counter, Address 18E (0x12) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Table 44 SerDes Loopback and SIGDET Control, Address 19E (0x13)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Table 45 Extended PHY Control 3, Address 20E (0x14) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Table 46 Extended PHY Control 4, Address 23E (0x17) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Table 47 SerDes MAC Status, Address 28E (0x1C) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Table 48 EPG Control Register 1, Address 29E (0x1D)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Table 49 EPG Control Register 2, Address 30E (0x1E)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Table 50 General-Purpose Registers Page Space  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
Table 51 SIGDET vs. GPIO Control, Address 13G (0x0D)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Table 52 GPIO Input, Address 15G (0x0F) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Table 53 GPIO Output, Address 16G (0x10) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
Table 54 GPIO Input/Output Configuration, Address 17G (0x11) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58



VMDS-10312 VSC8662 Datasheet Revision 4.3 ix

Table 55 GPIO Input/Output Configuration, Address 19G (0x13) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Table 56 Two-Wire Serial Mux Control 1, Address 20G (0x14) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Table 57 Two-Wire Serial Mux Interface Status and Control, Address 21G (0x15) . . . . . . . . . . . . . . . . . . . . 58
Table 58 Two-Wire Serial Mux Data Read/Write, Address 22G (0x16) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Table 59 Recovered Clock 1, Address 23G (0x17) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Table 60 Recovered Clock 2, Address 24G (0x18) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Table 61 Available Clock Squelch Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Table 62 LED Port Swapping, Address 25G (0x19)  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Table 63 CMODE Configuration Pins and Device Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Table 64 Device Functions and Associated CMODE Pins  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Table 65 CMODE Resistor Values and Resultant Bit Settings  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Table 66 DC Characteristics for Pins Referenced to VDDIO at 3.3 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Table 67 DC Characteristics for Pins Referenced to VDDIO at 2.5 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Table 68 DC Characteristics for Pins Referenced to VDDIO at 1.8 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Table 69 DC Characteristics for Pins Referenced to VDD33 at 3.30 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Table 70 DC Characteristics for MAC_RDP/N_n and FIBR_DOP/N_n Pins . . . . . . . . . . . . . . . . . . . . . . . . . 67
Table 71 DC Characteristics for MAC_TDP/N_n and FIBR_DIP/N_n Pins . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Table 72 DC Characteristics for LED[3:0]_n Pins  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Table 73 DC Characteristics for JTAG Pins  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Table 74 Typical Current Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Table 75 Current Consumption in SerDes/SGMII to 1000BASE-X Mode  . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Table 76 Consumption in SerDes/SGMII to 100BASE-FX or SerDes Pass-Through Mode  . . . . . . . . . . . . . 69
Table 77 AC Characteristics for REFCLK Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Table 78 AC Characteristics for REFCLK Input with 25 MHz Clock Input . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Table 79 AC Characteristics for the CLKOUT Pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Table 80 AC Characteristics for the RCVRD_CLK Pins  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Table 81 AC Characteristics for MAC_RDP/N_n and FIBR_DOP/N_n Pins . . . . . . . . . . . . . . . . . . . . . . . . . 71
Table 82 AC Characteristics for MAC_TDP/N_n and FIBR_DIP/N_n Pins . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Table 83 AC Characteristics for the JTAG Interface  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Table 84 AC Characteristics for the SMI Interface  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Table 85 AC Characteristics for Device Reset  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Table 86 AC Characteristics for Serial LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Table 87 Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Table 88 Stress Ratings  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Table 89 Pin Type Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
Table 90 GPIO Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Table 91 JTAG Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Table 92 Miscellaneous Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Table 93 Power Supply Pins  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Table 94 Power Supply and Associated Function Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Table 95 SerDes MAC Interface Pins  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Table 96 SerDes Media Interface Pins  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Table 97 SMI Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Table 98 Twisted Pair Interface Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Table 99 Thermal Resistances  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Table 100 Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99



Revision History

VMDS-10312 VSC8662 Datasheet Revision 4.3 1

1 Revision History

1.1

This section describes the changes that were implemented in this document. The changes are listed by 
revision, starting with the most current publication.

Revision 4.3
Revision 4.3 of this datasheet was published in April 2019. The following is a summary of the changes 
implemented in the datasheet:

• Key Features section was updated. For more information, see Key Features, page 3.
• VeriPHY Conrol 1 through VeriPHY Control 3 sections were deleted. For more information, see

Extended Page Registers, page 49.
• VeriPHY™ Cable Diagnostics section was updated. For more information, see VeriPHY Cable

Diagnostics, page 25.
• Illustrations for the SerDes MAC and SGMII MAC connections were updated to show the

appropriate capacitance for MAC_TDP and MAC_TDN. For more information, see Figure 3, page 6
and Figure 4, page 7.

• Timeout values for the ActiPHY link status timeout control bits were corrected. For more information,
see Table 36, page 46.

• Bit description for the SIGDET pin polarity (bit 0) was clarified that it is a sticky bit. For more
information, see Table 44, page 52

1.2 Revision 4.2
Revision 4.2 of this datasheet was published in May 2014. The following is a summary of the changes 
implemented in the datasheet:

• SerDes MAC and media interface descriptions and graphics were updated to remove references to
integrated AC decoupling capacitors in the receive path.

• Total jitter receive tolerance specification for SerDes MAC and media inputs were updated to remove
minimum values.

1.3 Revision 4.1
Revision 4.1 of this datasheet was published in April 2011. In revision 4.1 of the document, the 
VSC8662XIC-03 part was added. VSC8662XIC-03 supports an operating temperature range of –40 °C 
ambient to 100 °C case.

1.4 Revision 4.0
Revision 4.0 of this datasheet was published in June 2010. There were no changes to the technical 
content of the document. The datasheet was updated to reflect that the product is now in full production.

1.5 Revision 2.0
Revision 2.0 of this datasheet was published in May 2010. This was the first publication of the document.



Overview

VMDS-10312 VSC8662 Datasheet Revision 4.3 2

2 Overview

The VSC8662 device is a low-power, dual Gigabit Ethernet transceiver. It is designed for use in 
applications such as multiport switches and routers, where its compact ball grid array (BGA) packaging, 
low electromagnetic interference (EMI) line driver, and integrated line side termination resistors conserve 
both power and printed circuit board (PCB) space. Using the VSC8662 device in your design makes it 
possible to lower the component count without sacrificing capabilities or utility, resulting in more cost-
effective production and deployment.

Vitesse’s mixed signal and digital signal processing (DSP) architecture—a key operational feature of the 
VSC8662 device—assures robust performance even under less-than-favorable environmental 
conditions. It supports both half-duplex and full-duplex 10BASE-T, 100BASE-TX, and 1000BASE-T 
communication speeds over Category 5 (Cat5) unshielded twisted pair (UTP) cable at distances greater 
than 140 m, displaying excellent tolerance to NEXT, FEXT, echo, and other types of ambient 
environment and system electronic noise. 

The following illustration shows a high-level, generic view of a VSC8662 application.

Figure 1 • Typical Application

1.2 V 3.3 VSGMII, SerDes

VSC8662
Dual

10/100/1000BASE-T
100BASE-FX/1000BASE-X

Gigabit Ethernet 
Transceiver PHY

with SFP Mux Controller 
and

Recovered Clock Outputs

10/100/1000 Mbps Ethernet MAC

10/100/1000 Mbps Ethernet MAC

RJ-45 and Magnetics

Optics / SFP
SerDes

SCL/SDA

RJ-45 and Magnetics

Optics / SFP
SerDes

SCL/SDA

RCVRD_CLK1
RCVRD_CLK2



Overview

VMDS-10312 VSC8662 Datasheet Revision 4.3 3

2.1 Key Features 
This section lists key aspects of the VSC8662 device functionality and design that distinguish it from 
similar products.

Low Power

• Low power consumption of 750 mW per port in 1000BASE-T mode and 242 mW in 1000BASE-X 
• ActiPHY™ power management system with built-in intelligence and saving modes
Wide Range of Support

• Compliant with IEEE 802.3 specifications
• Support for >16 kB jumbo frames in all speeds with programmable synchronization FIFOs
• Supports Cisco SGMII v1.8 and 1000BASE-X MACs, IEEE 1149.1 JTAG boundary scan, and IEEE 

1149.6 AC-JTAG
Flexibility

• Integrated dual two-wire serial multiplexer to control SFPs or PoE modules, eliminating the need for 
an external two-wire serial device for the control and status of SFP or PoE modules

• VeriPHY® cable diagnostics suite provides extensive network cable operating conditions and status
• Patented, low EMI line driver with integrated line side termination resistors
• Four programmable direct drive LEDs per port with on-chip filtering and bi-color LED support
• Serial LED interface option
• Advanced SerDes features to ensure robust performance on longer signal traces, such as 

backplanes
• Extensive test features (including near end, far end, and connector loopback, and Ethernet packet 

generator with CRC error counter) to decrease time-to-market
Synchronous Ethernet

• Recovered clock output support for G.8261 Synchronous Ethernet applications, including 
programmable squelch control

• Patent-pending, fast link fail indication (<1 ms) to provide an earlier indication of a link failure to 
critical metro Ethernet traffic and synchronization links

2.2 Block Diagram
The following illustration shows the primary functional blocks of the VSC8634VSC8662VSC8664 
device.



Overview

VMDS-10312 VSC8662 Datasheet Revision 4.3 4

Figure 2 • VSC8662 Block Diagram

LED[3:0]_n

MAC_TDP_n

MAC_TDN_n

MAC_RDP_n

MAC_RDN_n

TXVP_A_n
TXVN_A_n
TXVP_B_n
TXVN_B_n
TXVP_C_n
TXVN_C_n
TXVP_D_n
TXVN_D_n

Se
ria

l M
AC

 In
te

rfa
ce

 (S
er

De
s)

10/100/
1000BASE-T 

PCS

10/100/
1000BASE-T 

PMA

MDI
Twisted Pair 

Interface

CMODE[7:0]
NRESET

NSRESET
MDC

MDIO
MDINTn

GPIO[15:10]
GPIO[7:6]
GPIO[3:2]

Management 
and

Control Interface
(MIIM)

JTAG

TD
I

TD
O

TC
K

TM
S

TR
ST

PLL and Analog

XTAL1/REFCLK
XTAL2
REF_FILT
REF_REXT
CLKOUT

LED Interface

Au
to

-N
eg

ot
ia

tio
n 

(S
GM

II,
 F

IF
Os

)

1000BASE-X
PCS

1000BASE-X
PMA

FIBR_DOP_n
FIBR_DON_n

FIBR_DIP_n
FIBR_DIN_n

SIGDET_n/
GPIO[1:0]

I2C_SDA/
GPIO[8]

I2C_SCL_n/
GPIO[5:4]

100BASE-FX
PCS

100BASE-FX
PMA

MDI
SerDes 

Interface
and

I2C Mux

10/100/1000BASE-T SFP Data Path

Sync Ethernet
RCVRD_CLK1
RCVRD_CLK2
FastLinkFail/
GPIO[9]



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 5

3 Functional Descriptions

This section provides detailed information about how the VSC8662 device works, what configurations 
and operational features are available, and how to test its function. It includes descriptions of the various 
device interfaces and how to set them up.

With the information in this section, you can better determine which device setup parameters you must 
access to configure the VSC8662 device to work in your application. There are two ways to configure the 
VSC8662 device. You can access and set its internal memory registers or use a combination of the 
device CMODE pins and its registers.

For information about the VSC8662 device registers, see Configuration, page 28.

For information about the device CMODE pins, see CMODE, page 61.

3.1 Operating Modes
With respect to its function in your design, the VSC8662 device acts as the interface between a media 
access controller (MAC) and either Category 5 (Cat5) media, 100BASE-FX fiber media, or 1000BASE-X 
fiber media. The VSC8662 device can also act as a MAC-to-MAC pass-through device to support triple-
speed copper SFPs.

Depending on the speed of data throughput required in your application, the MAC may be either a 
SerDes or an SGMII device, and can also be configured to support twisted pair Cat5 cabling, 100BASE-
FX/1000BASE-X fiber optic cabling, or copper small form factor pluggable (SFP) devices.

As shown in the following table, the operating mode you choose when setting up the VSC8662 device is 
a function of which type of MAC is to be connected, which data throughput speeds are required in the 
application, and the type of Cat5 media support required. 

Table 1 • Operating Mode vs. Speed

VSC8662 Mode
10/100/1000BAS
E-T Support

1000BASE-X 
Fiber Optic 
Support

100BASE-FX 
Fiber Optic 
Support

10/100/
1000BASE-T 
Copper SFP 
Support

SerDes MAC-to-Cat5 Link Partner 1000BASE-T 
only

SGMII MAC-to-Cat5 Link Partner Yes

SerDes MAC-to-1000 Mbps SerDes with Auto-
Negotiation

Yes 1000BASE-T 
only

SGMII MAC-to-1000 Mbps SerDes with Auto-
Negotiation

Yes 1000BASE-T 
only

SerDes MAC-to-1000 Mbps SerDes with Pass-
Through

Yes(1) 1000BASE-T 
only(1)

SGMII MAC-to-SGMII with Pass-Through Yes(1) Yes(1) Yes(1)

SGMII MAC-to-100BASE-FX Yes

SerDes MAC with automatic media sense 
(AMS) and 1000 Mbps SerDes with Auto-
Negotiation

1000BASE-T 
only

Yes 1000BASE-T 
only

SGMII MAC with AMS and 1000 Mbps SerDes 
with Auto-Negotiation

Yes Yes 1000BASE-T 
only

SGMII MAC with AMS and 100BASE-FX Yes Yes



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 6

3.2 SerDes MAC Interface
The VSC8662 SerDes MAC interface performs data serialization and deserialization functions using an 
integrated SerDes block. The interface operates at 1.25 Gbps speed, providing full-duplex and half-
duplex 1000 Mbps bandwidth for SerDes mode and 10/100/1000 Mbps bandwidth for SGMII mode.

The SerDes MAC block has the termination resistor integrated into the device.

3.2.1 SerDes MAC
When connected to a SerDes MAC compliant to 1000BASE-X, the VSC8662 device provides data 
throughput at a rate of 1000 Mbps only; 10 Mbps and 100 Mbps rates are not supported. To configure the 
device for SerDes MAC mode set register 23, bit 12 = 1. This device also supports 1000BASE-X clause 
37 MAC-side auto-negotiation and is enabled through register 23, bit 13. To configure the rest of the 
device for 1000 Mbps only operation, select the 1000BASE-T-only by disabling the 10/100BT 
advertisements in register 4 or using CMODE7, bit 1:0 to advertise 1000 Mbps only.

The following illustration shows a typical connection of the VSC8662 device to a SerDes MAC.

Figure 3 • SerDes MAC Interface

3.2.2 SGMII MAC
When configured to detect and switch between 10BASE-T, 100BASE-T, and 1000BASE-T data rates, the 
VSC8662 device can be connected to an SGMII-compatible MAC. To configure the device for SGMII 
MAC mode, set register 23, bit 12 = 0. This device also supports SGMII MAC-side auto-negotiation and 
is enabled through register 23, bit 13.

By default, the SGMII version supported is 1.7. Version 1.8 is also supported by setting register 20E, bit 
15 = 1.

The following illustration shows a typical connection of the VSC8662 device to an SGMII-compatible 
MAC.

SerDes MAC with AMS and Pass-Through 1000BASE-T 
only

Yes(1) 1000BASE-T 
only(1)

SGMII MAC with AMS and Pass-Through Yes Yes(1) Yes(1) Yes(1)

1. Because the device acts as a pass-through, the MAC must be capable of supporting this media.

Table 1 • Operating Mode vs. Speed (continued)

VSC8662 Mode
10/100/1000BAS
E-T Support

1000BASE-X 
Fiber Optic 
Support

100BASE-FX 
Fiber Optic 
Support

10/100/
1000BASE-T 
Copper SFP 
Support

SerDes MAC VSC8662 
PHY Port_n

MAC_TDP

MAC_TDN

MAC_RDN

MAC_RDP

RDN

RDP

TDN

TDP
100 Ω 
or 
150 Ω

0.1 µF

0.1 µF

100 Ω 
or 
150 Ω

100 Ω 
or 
150 Ω

0.1 µF

0.1 µF



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 7

Figure 4 • SGMII MAC Interface

3.3 SerDes Media Interface
The VSC8662 device SerDes media interface performs data serialization and deserialization functions 
using an integrated SerDes block in the SerDes media interface. The interface operates at 1.25 Gbps 
speed, providing full-duplex and half-duplex for 10/100/1000 Mbps bandwidth that can connect directly to 
100BASE-FX/1000BASE-X-compliant optical devices as well as to 10/100/1000BASE-T copper SFP 
devices. The interface can be operated in three SerDes modes: 

• SerDes Media with PCS Auto-Negotiation
• SerDes Pass-Through mode
• SGMII to MAC-to-100BASE-FX mode
The SerDes media block has the termination resistor integrated into the device.

3.3.1 SerDes Media with PCS Auto-Negotiation
The SerDes with Media Interface PCS Auto-Negotiation mode supports IEEE standard 802.3, clauses 36 
and 37, which describe 1000BASE-X fiber auto-negotiation. In this mode, control and status of the 
SerDes media is displayed in the VSC8662 device registers 0 through 15 in a manner similar to what is 
described in the IEEE standard 802.3, clause 28. In this mode, connected copper SFPs can only operate 
at 1000BASE-T speed. A link in this mode is established using auto-negotiation (enabled or disabled) 
between the PHY and the link partner. To configure the PHY in this mode, set register 23, bits 10:8 = 010. 
To configure 1000BASE-X auto-negotiation for this mode, set Register 0, bit 12.

Registers 0 through 15 per clause 37 are mapped over the clause 28 register when the PHY connects to 
a fiber link partner. Consequently, the registers used to control copper per clause 28 have the same 
function as clause 37 when a fiber link partner is present.

For information about how the VSC8662 LEDs operate in this mode, see LED Behavior, page 19.

3.3.2 SerDes Pass-Through Mode
SerDes with Pass-Through mode is a feature that links a fiber module or copper SFP directly to the 
SerDes interface of the MAC through the VSC8662 device. For example, to support 10/100/1000 copper 
SFPs, the MAC must be able to operate in SGMII mode. Because the MAC controls the establishment of 
the link, PHY registers 0 through 15 do not indicate link information when in SerDes Pass-Through 
mode. To configure the PHY in this mode, set register 23, bits 10:8 = 001. Also, to establish the link, 
assert the SIGDET pin. 

All relevant LED modes are supported except for Collision, Duplex, and Auto-negotiation Fault. This 
means that a triple-speed copper SFPs link up and data type can be indicated by the PHY’s LEDs.

SGMII MAC VSC8662 
PHY Port_n

MAC_TDP

MAC_TDN

MAC_RDN

MAC_RDP

RDN

RDP

TDN

TDP
100 Ω 
or 
150 Ω

0.1 µF

0.1 µF

100 Ω 
or 
150 Ω

100 Ω 
or 
150 Ω

TCN

TCP

0.1 µF

0.1 µF



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 8

3.3.3 SGMII MAC-to-100BASE-FX Mode
The VSC8662 can support the 100BASE-FX communication speed to connect to fiber modules, such as 
GBICs and SFPs.

This capability is facilitated by using the connections on the SerDes pins when connected to a MAC 
through SGMII only. SGMII is required as it can transmit in 100 Mbps, whereas the SerDes MAC can 
only transmit 1000 Mbps. Ethernet Package Generator (EPG), cyclical redundancy checking (CRC) 
counters, and loopback modes are supported in the 100BASE-FX over SGMII mode. For information 
about how the VSC8662 LEDs operate in this mode, see LED Behavior, page 19. To configure the PHY 
in this mode, set register 23, bits 10:8 = 011.

3.3.4 Unidirectional Transport for Fiber Media
In addition, the VSC8662 device supports 802.3ah for unidirectional transport across its 1000BASE-X 
and 100BASE-FX fiber media. This feature enables transmission across fiber media, regardless of 
whether the PHY has determined that a valid link has been established (register 1, bit 2). The only valid 
operating modes for unidirectional fiber mode are 100BASE-FX or 1000BASE-X fiber media (set in 
register 23). SerDes pass-through mode is unidirectional by default. 

To enable this feature, set register 0, bit 5 to 1. For status of the unidirectional ability, read register 1, 
bit 7. 

Note Auto-media sense will not work with this feature. In addition, because unidirectional fiber media 
needs auto-negotiation disabled, this means that SGMII auto-negotiation must also be disabled (register 
23, bit 13 = 0), and full-duplex mode must be enabled (register 0, bit 8 = 1).

3.4 Advanced SerDes Features
The VSC8662 device is equipped with advanced SerDes features that allow for a robust SerDes link 
performance.

3.4.1 SerDes Receiver Equalization
To achieve better SerDes performance on longer signal traces (such as backplanes), the VSC8662 
device has a built-in SerDes receiver equalization circuit. When enabled, the SerDes MAC receiver is 
capable of decoding a given receive signal with greater sensitivity, thereby achieving longer circuit 
lengths. This feature is found in register 17E.

3.4.2 SerDes Transmitter Amplitude Control
To achieve better SerDes performance on longer signal traces (such as backplanes), the VSC8662 
device has a built-in SerDes transmitter amplitude control. The SerDes MAC transmitter is capable of 
adjustment by the user to achieve the optimal transmitted signal. This feature is found in register 17E.

3.4.3 SerDes Link Integrity Information
The VSC8662 device has included several link control and status register bits to help a customer debug 
and monitor their SerDes link integrity during operation. These capabilities are found in registers 27 and 
28E.

3.5 Cat5 Twisted Pair Media Interface
The VSC8662 device twisted pair interface is compliant with the IEEE standard 802.3-2002. 

3.5.1 Voltage-Mode Line Driver
Unlike many other gigabit PHYs, the VSC8662 device uses a patented voltage-mode line driver that 
allows it to fully integrate the series termination resistors (required to connect the PHY’s Cat5 interface to 
an external 1:1 transformer). Also, the interface does not require the user to place an external voltage on 
the center tap of the magnetic. The following illustration shows the connections.



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 9

Figure 5 • Cat5 Media Interface

3.5.2 Cat5 Auto-Negotiation and Parallel Detection
The VSC8662 device supports twisted pair auto-negotiation as defined by clause 28 of the IEEE 
standard 802.3-2002. The auto-negotiation process evaluates the advertised capabilities of the local 
PHY and its link partner to determine the best possible operating mode. In particular, auto-negotiation 
can determine speed, duplex configuration, and master or slave operating modes for 1000BASE-T. Auto-
negotiation also allows a connected MAC to communicate with its link partner MAC through the 
VSC8662 device using optional “next pages,” which set attributes that may not otherwise be defined by 
the IEEE standard.

If the Cat5 link partner does not support auto-negotiation, the VSC8662 device automatically uses 
parallel detection to select the appropriate link speed.

Auto-negotiation can be disabled in register 0, bit 12. If auto-negotiation is disabled, the state of register 
bits 0.6, 0.13, and 0.8 determine the device operating speed and duplex mode. Note that while 10BASE-
T and 100BASE-T do not require auto-negotiation, clause 40 has defined 1000BASE-T to require auto-
negotiation. For more information about configuring auto-negotiation, see IEEE Standard and Main 
Registers, page 29.

3.5.3 Automatic Crossover and Polarity Detection
For trouble-free configuration and management of Ethernet links, the VSC8662 device includes a robust 
automatic crossover detection feature for all three speeds on the twisted-pair interface (10BASE-T, 
100BASE-T, and 1000BASE-T). Known as HP Auto-MDIX, the function is fully compliant with clause 40 
of the IEEE standard 802.3-2002.

Additionally, the device detects and corrects polarity errors on all MDI pairs—a useful capability that 
exceeds the requirements of the standard.

Both HP Auto-MDIX detection and polarity correction are enabled in the device by default. You can 
change the default settings using device register bits 18.5:4. Status bits for each of these functions are 
located in register 28.

TXVP_A_n 1

RJ-45
VSC8662

PHY Port_n

TXVN_A_n

TXVP_B_n

TXVN_B_n

TXVP_C_n

TXVN_C_n

TXVP_D_n

TXVN_D_n

Transformer

0.1 µF

0.1 µF

0.1 µF

0.1 µF

2

3

6

4

5

7

8

A+

A–

B+

B–

C+

C–

D+

D–

1000 pF, 2 kV

75 Ω

75 Ω

75 Ω

75 Ω



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 10

Note The VSC8662 device can be configured to perform HP Auto-MDIX even when auto-negotiation is 
disabled (setting register 0.12 to 0) and the link is forced into 10/100 speeds. To enable this feature, set 
register 18.7 to 0.

The HP Auto-MDIX algorithm successfully detects, corrects, and operates with any of the MDI wiring pair 
combinations listed in the following table. 

3.5.4 Manual MDI/MDI-X Setting
As an alternative to HP Auto-MDIX detection, you can force the PHY to be MDI or MDI-X using register 
19E, bits 3:2. Setting these bits to 10 forces MDI and setting 11 forces MDI-X. Leaving the bits 00 
enables the MDI/MDI-X setting to be based on register 18, bits 7 and 5.

3.5.5 Link Speed Downshift
For operation in cabling environments that are incompatible with 1000BASE-T, the VSC8662 device 
provides an automatic link speed “downshift” option. When enabled, the device automatically changes its 
1000BASE-T auto-negotiation advertisement to the next slower speed after a set number of failed 
attempts at 1000BASE-T.

This is useful in setting up in networks using older cable installations that may include only pairs A and B 
and not pairs C and D.

You can configure and monitor link speed downshifting using register bits 20E.4:1. For more information, 
see Extended PHY Control Set 1, page 40.

3.6 Automatic Media-Sense (AMS) Interface Mode
This mode can automatically set the media interface to Cat5 mode or to SerDes mode. The active media 
mode chosen is based on the automatic media-sense (AMS) preferences set in the device register 23, bit 
11.

The following illustration shows a block diagram of the AMS functionality in the VSC8662 device.

Table 2 • Supported MDI Pair Combinations

RJ-45 Pin Pairings
1, 2 3, 6 4, 5 7, 8 Mode
A B C D Normal MDI

B A D C Normal MDI-X

A B D C Normal MDI with pair swap on C and D pair

B A C D Normal MDI-X with pair swap on C and D pair



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 11

Figure 6 • Automatic Media Sense Block Diagram

When both SerDes and Cat5 media interfaces attempt to establish a link, the preferred media interface 
overrides a link-up of the non-preferred media interface. For example, if the preference is set for SerDes 
mode and Cat5 media establishes a link, then Cat5 becomes the active media interface. However, after 
the SerDes media interface establishes a link, the Cat5 interface drops its link because the preference 
was set for SerDes mode. In this scenario, the SerDes preference determines the active media source 
until the SerDes link is lost. Also, Cat5 media cannot link up unless there is no SerDes media link 
established.

The following table lists the available AMS preferences. 

The status of the media mode selected by the AMS can be read from device register 20E, bits 7:6. It 
indicates whether copper media, SerDes media, or no media is selected.

Each PHY has three auto-media sense modes. The difference between the modes is based on the 
SerDes media modes:

• SerDes with PCS Auto-Negotiation (register 23, bit 10:8 = 110)
• SerDes with Pass-Through (register 23, bit 10:8 = 101)
• 100BASE-FX (register 23, bit 10:8 = 111)
For more information about SerDes media mode functionality with AMS enabled, see SerDes Media 
Interface, page 7. 

For AMS with SerDes auto-negotiation and also 100BASE-FX, the status and control of both the Cat5 
and the SerDes media can be made using registers 0 through 15. For AMS with SerDes pass-through, 
only the Cat5 interface can have its interface control and status monitored. The SerDes media must then 
be controlled and monitored within the MAC.

3.7 Transformerless Ethernet
The Cat5 media interface supports 10/100/1000BT Ethernet for backplane applications such as those 
specified by the PICMG™ 2.16 and ATCA™ 3.0 specifications for eight-pin channels. With proper AC 
coupling, the typical Cat5 transformer can be removed and replaced with capacitors. 

Table 3 • AMS Media Preferences

Preference 
Setting

Cat5 Linked,
Fiber Not Linked

SerDes Linked,
Cat5 Not Linked

Cat5 Linked,
SerDes Attempts 
to Link

SerDes Linked,
Cat5 Attempts to 
Link

Both Cat5 and 
SerDes Attempt 
to Link

SerDes Cat5 SerDes SerDes SerDes SerDes

Cat5 Cat5 SerDes Cat5 Cat5 Cat5

TD
RD

Auto Sense
Logic

Cat5

Fiber Optic 
Module

MAC

VSC8662 port_n

SIGDET

SerDes

SGMII /
Serial MAC



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 12

3.8 Ethernet Inline Powered Devices
The VSC8662 device can detect legacy inline powered devices in Ethernet network applications. Its 
inline powered detection capability can be part of a system that allows for IP-phone and other devices 
such as wireless access points to receive power directly from their Ethernet cable, similar to office digital 
phones receiving power from a Private Branch Exchange (PBX) office switch over the telephone cabling. 
This can eliminate the need for an IP-phone to have an external power supply. It also enables the inline 
powered device to remain active during a power outage (assuming the Ethernet switch is connected to 
an uninterrupted power supply, battery, back-up power generator, or some other uninterruptable power 
source).

For more information about legacy inline powered device detection, visit the Cisco Web site at 
www.cisco.com.

The following illustration shows an example of this type of application. 

Figure 7 • Inline Powered Ethernet Switch Diagram

The following procedure describes the process that an Ethernet switch must perform in order to process 
inline power requests made by a link partner (LP) that is, in turn, capable of receiving inline power.

1. Enable the inline powered device detection mode on each VSC8662 PHY using its serial 
management interface. Set register bit 23E.10 to 1.

2. Ensure that the VSC8662 device Auto-Negotiation Enable bit (register 0.12) is also set to 1. In the 
application, the device sends a special Fast Link Pulse (FLP) signal to the LP. Reading register bit 
23E.9:8 returns 00 during the search for devices that require Power-over-Ethernet (PoE).

3. The VSC8662 PHY monitors its inputs for the FLP signal looped back by the LP. An LP capable of 
receiving PoE loops back the FLP pulses when the LP is in a powered-down state. This is reported 
when VSC8662 device register bit 23E.9:8 reads back 01. It can also be verified as an inline power 
detection interrupt by reading VSC8662 device register bit 26.9, which should be a 1, and which is 

SMI Control

Processor

PHY 2

SGMII 
Interface

Inline,
Power-Over-Ethernet

(PoE)
Power Supply

Cat5

Gigabit Switch

PHY 1 PHY n

Transformer

RJ-45
I/F

Transformer

RJ-45
I/F

Transformer

RJ-45
I/F

Link
Partner

Link
Partner

Link
Partner



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 13

subsequently cleared and the interrupt de-asserted after the read. If an LP device does not loop 
back the FLP after a specific time, VSC8662 device register bit 23E.9:8 automatically resets to 10.

4. If the VSC8662 PHY reports that the LP needs PoE, the Ethernet switch must enable inline power 
on this port, externally of the PHY.

5. The PHY automatically disables inline powered device detection if the VSC8662 device register bit 
23E.9:8 automatically resets to 10, and then automatically changes to its normal auto-negotiation 
process. A link is then auto-negotiated and established when the link status bit is set (register bit 1.2 
is set to 1).

6. In the event of a link failure (indicated when VSC8662 device register bit 1.2 reads 0), the inline 
power should be disabled to the inline powered device external to the PHY. The VSC8662 PHY 
disables its normal auto-negotiation process and re-enables its inline powered device detection 
mode.

3.9 IEEE 802.3af PoE Support
The VSC8662 device is also compatible with switch designs that are intended for use in systems that 
supply power to Data Terminal Equipment (DTE) by means of the MDI or twisted pair cable, as described 
in clause 33 of the IEEE standard 802.3af. 

3.10 ActiPHY Power Management
In addition to the IEEE-specified power-down control bit (device register bit 0.11), the device also 
includes an ActiPHY™ power management mode for each PHY. This mode enables support for power-
sensitive applications. It utilizes a signal-detect function that monitors the media interface for the 
presence of a link to determine when to automatically power-down the PHY. The PHY “wakes up” at a 
programmable interval and attempts to “wake-up” the link partner PHY by sending a burst of FLP over 
copper media.

The ActiPHY™ power management mode in the VSC8662 device is enabled on a per-port basis during 
normal operation at any time by setting register bit 28.6 to 1.

There are three operating states possible when ActiPHY™ mode is enabled:

• Low power state
• LP wake-up state
• Normal operating state (link up state)
The VSC8662 device switches between the low power state and LP wake-up state at a programmable 
rate (the default is two seconds) until signal energy has been detected on the media interface pins. When 
signal energy is detected, the PHY enters the normal operating state. If the PHY is in its normal operating 
state and the link fails, the PHY returns to the low power state after the expiration of the link status time-
out timer. After reset, the PHY enters the low power state.

When auto-negotiation is enabled in the PHY, the ActiPHY state machine operates as described. If auto-
negotiation is disabled and the link is forced to use 10BT or 100BTX modes while the PHY is in its low 
power state, the PHY continues to transition between the low power and LP wake-up states until signal 
energy is detected on the media pins. At that time, the PHY transitions to the normal operating state and 
stays in that state even when the link is dropped. If auto-negotiation is disabled while the PHY is in the 
normal operation state, the PHY stays in that state when the link is dropped and does not transition back 
to the low power state.

The following illustration shows the relationship between ActiPHY states and timers.



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 14

Figure 8 • ActiPHY State Diagram

3.10.1 Low Power State
In the low power state, all major digital blocks are powered down. However, the following functionality is 
provided:

• SMI interface (MDC, MDIO, MDINTn)
• CLKOUT
In this state, the PHY monitors the media interface pins for signal energy. The PHY comes out of low 
power state and transitions to the normal operating state when signal energy is detected on the media. 
This happens when the PHY is connected to one of the following:

• Auto-negotiation capable link partner
• Another PHY in enhanced ActiPHY LP wake-up state
In the absence of signal energy on the media pins, the PHY transitions from the low power state to the 
LP wake-up state periodically based on the programmable sleep timer (register bits 20E.14:13). The 
actual sleep time duration is randomized from –80 milliseconds (ms) to +60 ms to avoid two linked PHYs 
in ActiPHY mode entering a lock-up state during operation.

3.10.2 Link Partner Wake-up State
In this state, the PHY attempts to wake up the link partner. Up to three complete FLP bursts are sent on 
alternating pairs A and B of the Cat5 media for a duration based on the wake-up timer, which is set using 
register bits 20E.12:11. 

In this state, the following functionality is provided:

• SMI interface (MDC, MDIO, MDINTn)
• CLKOUT
After sending signal energy on the relevant media, the PHY returns to the low power state.

3.10.3 Normal Operating State
In this state, the PHY establishes a link with a link partner. When the media is unplugged or the link 
partner is powered down, the PHY waits for the duration of the programmable link status time-out timer, 
which is set using register bit 28.7 and bit 28.2. It then enters the low power state.

3.11 Media Recovered Clock Outputs
For Synchronous Ethernet applications, the VSC8662 includes two recovered clock output pins: 
RCVRD_CLK1 (F16) and RCVRD_CLK2 (G16), which are controlled by registers 23G and 24G, 
respectively. These pins are synchronized to the clock of the active media link. 

Low Power State

LP Wake-up State Normal Operation State

FLP Burst or
Clause 37 Restart 

Signal Sent

Sleep Timer Expires
Timeout Timer Expires and
 Auto-negotiation Enabled

Signal Energy Detected on 
Media



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 15

To enable recovered clock output, set register 23G or 24G, bit 15, to 1. (By default, the RCVRD_CLK1 
and RCVRD_CLK2 pins are disabled and held low, including when NRESET or NSRESET is asserted.) 
Registers 23G and 24G also control the PHY port for clock output, the clock source, the clock frequency 
(either 25 MHz or 125 MHz), and squelch conditions. For more information about disabling the recovered 
clock, see Disabling Recovered Clock Output, page 98.

3.11.1 Clock Selection Settings
On each pin, the recovered clock can come from the following sources, as set by registers 23G or 24G, 
bits 1:0:

• Fiber SerDes media
• Copper media
• Copper transmitter TCLK output (RCVRD_CLK1 only)
• Local XTAL1/REFCLK input coming into the device 
Note 1 When using the Auto-Media Sense feature, the recovered clock output cannot automatically 
change between each active media. Changing the media source must be managed through the 
recovered clock register settings. 

Note 2 The 10BASE-T and 1000BASE-T master are not effective modes for Synchronous Ethernet 
clock recovery. In the case of 10BASE-T master mode, the receiver does not produce a reliable 
continuous clock source. In the case of 1000BASE-T master mode, the clock is based on the VSC8662 
REFCLK pin, which is a local clock.

3.11.2 Clock Output Squelch
Under certain conditions, the PHY outputs a clock based on the XTAL1/REFCLK pin, such as when there 
is no link present or during auto-negotiation. To prevent an undesirable clock from appearing on the 
recovered clock pins, the VSC8662 squelches (that is, inhibits) the clock output based on any of the 
following criteria:

• No link is detected (the link status register 1, bit 2 = 0).
• The link is found to be unstable using the fast link failure detection feature (GPIO9 pin is asserted 

high).
• The active link is in 10BASE-T or in 1000BASE-T master mode. These modes produce unreliable 

recovered clock sources.
Use register 23G or 24G, bits 5:4 to configure the clock squelch criteria. These registers can also disable 
the squelch feature. 

3.12 Fast Link Failure Indication
To aid Synchronous Ethernet applications, the VSC8662 can indicate the onset of a link failure in less 
than 1 ms. By comparison, the IEEE 802.3 standard establishes a delay up to 750 ms before indicating 
that a 1000BASE-T link is no longer present. Having a fast link failure indication is critical to support ports 
used in a synchronization timing link application. The fast link failure indication works for all copper and 
fiber media speeds.

The GPIO9 pin serves as the main indicator for a fast link failure. To enable fast link failure indication, set 
register 19E, bit 4 to 1 (0 is the default). Set the applicable PHY port in register 19G, bits 1:0. When a link 
on the selected port is failing, the GPIO9 pin asserts high and remains high until the link is re-established 
or until register 19G.1:0 is changed to a PHY port with an established link. 

The fast link failure indication is also available on the serial management interface interrupt pins 
(MDINTn) for each PHY port. To enable this function, set register 25, bit 7 to 1. The MDINT pins assert if 
register 26, bit 7 is set to 1, and the pins clear once register 26 is read.

Note For all links except 1000BASE-T, the fast link failure indication matches the link status register 
(address 1, bit 2). For 1000BASE-T links, the link failure is based on a circuit that will analyze the integrity 
of the link and, at the indication of failure, will assert.



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 16

3.13 Serial Management Interface
The VSC8662 device includes an IEEE 802.3-compliant serial management interface (SMI) that is 
affected by use of its MDC and MDIO pins. The SMI provides access to device control and status 
registers. The register set that controls the SMI consists of 32 16-bit registers, including all required 
IEEE-specified registers. Also, there are additional pages of registers accessible using device register 
31.

For more information, see Extended Page Registers, page 49.

The SMI is a synchronous serial interface with bidirectional data on the MDIO pin that is clocked on the 
rising edge of the MDC pin. The interface can be clocked at a rate from 0 MHz to 12.5 MHz, depending 
on the total load on MDIO. An external, 2 kΩ pull-up resistor is required on the MDIO pin.

3.13.1 SMI Frames
Data is transferred over the SMI using 32-bit frames with an optional and arbitrary length preamble. The 
following illustrations show the SMI frame format for the read operation and write operation.

Figure 9 • SMI Read Frame

Figure 10 • SMI Write Frame

The following provides additional information about the terms used in Figure 9 and Figure 10.

Idle During idle, the MDIO node goes to a high-impedance state. This allows an external pull-up resistor 
to pull the MDIO node up to a logical 1 state. Because the idle mode should not contain any transitions 
on MDIO, the number of bits is undefined during idle.

Preamble By default, preambles are not expected or required. The preamble is a string of ones. If it 
exists, the preamble must be at least one bit; otherwise, it may be of an arbitrary length.

Start of Frame (SFD) A pattern of 01 indicates the start of frame. If the pattern is not 01, all following 
bits are ignored until the next preamble pattern is detected.

Read or Write Opcode A pattern of 10 indicates a read. A 01 pattern indicates a write. If the bits are 
not either 01 or 10, all following bits are ignored until the next preamble pattern is detected.

PHY Address The VSC8662 device responds to a message frame only when the received PHY 
address matches its physical address. The physical address is five bits long (4:0). Bits 4:2 are set by the 
CMODE pins. Bit 1 is always 0 and bit 0 represents the PHY of the device being addressed. Note that 
this reserves PHY addresses 0–3, but only 0 and 1 should be used.

Register Address The next five bits are the register address.

MDC

MDIO

Preamble
(optional)

SFD

1Z 1 0

Read

1 0

PHY Address

A4 A3 A2 A1 A0 R4 R3 R2 R1 R0

Register Address
to PHY

Z 0

TA Register Data from PHY

D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Z Z

IdleIdle

Z

Station Manager Drives MDIO PHY Drives MDIO

MDC

MDIO

Preamble
(optional)

SFD

1Z 1 0

Write

0 1

PHY Address

A4 A3 A2 A1 A0 R4 R3 R2 R1 R0

Register Address
to PHY

1 0

TA Register Data from PHY

D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Z Z

IdleIdle

Z

Station Manager Drives MDIO (PHY tristates MDIO during entire sequence)



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 17

Turnaround The two bits used to avoid signal contention when a read operation is performed on the 
MDIO are called the turnaround (TA) bits. During read operations, the VSC8662 device drives the 
second TA bit, a logical 0.

Data The 16-bits read from or written to the device are considered the data or data stream. When data 
is read from a PHY, it is valid at the output from one rising edge of MDC to the next rising edge of MDC. 
When data is written to the PHY, it must be valid around the rising edge of MDC.

Idle The sequence is repeated.

3.13.2 SMI Interrupts
The SMI also includes an output interrupt signal, MDINTn, for signaling the station manager when certain 
events occur in the PHY. A separate MDINTn pin is included for each VSC8662 device PHY.

Each MDINTn pin can be configured for open-drain (active-low) by tying the pin to a pull-up resistor and 
to VDDIO. The following illustration shows this configuration.

Figure 11 • MDINTn Configured as an Open-Drain (Active-Low) Pin

Alternatively, each MDINTn pin can be configured for open-source (active-high) by tying the pin to a pull-
down resistor and to VSS. The following illustration shows this configuration.

Figure 12 • MDINTn Configured as an Open-Source (Active-High) Pin

If only one interrupt pin is required, each MDINTn pin can be tied together to a single pull-up or pull-down 
resistor in a wired-OR configuration.

When a PHY generates an interrupt, the MDINTn pin is asserted (driven high or low, depending on 
resistor connection) if the interrupt pin enable bit (MII register 25.15) is set.

3.14 LED Interface
The VSC8662 device drives up to four LEDs directly for each PHY port. All LED outputs are active-low 
and are driven using 3.3 V from the VDD33 power supply. The pins, mainly used to sink the current of the 
cathode side of an LED when active, can also supply power to the anode portion of LEDs when not in the 
active state. This allows for two LED pins to be used to drive a multi-status, bi-colored LED.

MDINTn
(to the Station

Manager)

Interrupt Pin Enable
(Register 25.15)

Interrupt Pin Status
(Register 26.15)

External Pull-Up
Resistor at the

Station Manager for
Open-Drain

(Active-Low Mode)

VDDIO

PHY_n

MDINTn

MDINTn
(to the Station 

Manager)

Interrupt Pin Enable
(Register 25.15)

Interrupt Pin Status
(Register 26.15) External Pull-down at 

the Station Manager
For Open-source

(Active-high Mode)

VDDIO

PHY_n

MDINTn



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 18

3.14.1 LED Modes
Each LED pin can be configured to display different status information. Set the LED mode either by using 
register 29 or the CMODE pin setting. For additional operating flexibility, LED output functions can be set 
on a per-port basis. 

The modes in the following table are equivalent to the setting used in register 29 to configure each LED 
pin. For all LED states, 1 = pin held high (de-asserted), 0 = pin held low (asserted), and the blink/pulse-
stretch is dependent on the LED behavior setting in register 30. 

Table 4 • LED Mode and Function Summary

Mode Function Name LED State and Description
0 Link/Activity(1) 1 = No link in any speed on any media interface.

0 = Valid link at any speed on any media interface.
Blink or pulse-stretch = Valid link at any speed on any media interface with 
activity present.

1 Link1000/Activity 1 = No link in 1000BASE-T or 1000BASE-X.
0 = Valid 1000BASE-T or 1000BASE-X link.
Blink or pulse-stretch = Valid 1000BASE-T or 1000BASE-X link with activity 
present.

2 Link100/Activity 1 = No link in 100BASE-TX or 100BASE-FX.
0 = Valid 100BASE-TX or 100BASE-FX link.
Blink or pulse-stretch = Valid 100BASE-TX or 100BASE-FX link with activity 
present.

3 Link10/Activity 1 = No link in 10BASE-T.
0 = Valid 10BASE-T link.
Blink or pulse-stretch = Valid 10BASE-T link with activity present.

4 Link100/1000/Activity 1 = No link in 100BASE-TX, 100BASE-FX, 1000BASE-X, or 1000BASE-T.
0 = Valid 100BASE-TX, 100BASE-FX, 1000BASE-X, or 1000BASE-T link.
Blink or pulse-stretch = Valid 100BASE-TX, 100BASE-FX, 1000BASE-X, or 
1000BASE-T link with activity present.

5 Link10/1000/Activity 1 = No link in 10BASE-T, 1000BASE-X, or 1000BASE-T.
0 = Valid 10BASE-T, 1000BASE-X, or 1000BASET-T link.
Blink or pulse-stretch = Valid 10BASE-T, 1000BASE-X, or 1000BASE-T link with 
activity present.

6 Link10/100/Activity 1 = No link in 10BASE-T, 100BASE-FX, or 100BASE-TX.
0 = Valid 10BASE-T or 100BASE-TX, 100BASE-FX, link.
Blink or pulse-stretch = Valid 10BASE-T, 100BASE-FX, or 100BASE-TX link with 
activity present.

7 Link100BASE-FX/
1000BASE-X/Activity

1 = No link in 100BASE-FX or 1000BASE-X.
0 = Valid 100BASE-FX or 1000BASE-X link.
Blink or pulse-stretch = Valid 100BASE-FX or 1000BASE-X link with activity 
present.

8 Duplex/Collision 1 = Link established in half-duplex mode, or no link established.
0 = Link established in full-duplex mode.
Blink or pulse-stretch = Link established in half-duplex mode but collisions are 
present.

9 Collision 1 = No collision detected.
Blink or pulse-stretch = Collision detected.

10 Activity 1 = No activity present.
Blink or pulse-stretch = Activity present (becomes TX activity present if register 
bit 30.14 is set to 1).



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 19

3.14.2 Extended LED Modes
In addition to the LED modes in register 29, there is also additional LED modes that are enabled 
whenever any of the Register 19E bits 15 to 12 are set to 1. These extended modes are shown in 
Table 5, page 19. For example, LED0 = Mode 17 means that Register 19E bit 12 = 1 and Register 30 bits 
3 to 0 = 0001. 

3.14.3 LED Behavior
Several LED behaviors can be programmed into the VSC8662 device. Use the settings in register 30 to 
program LED behavior, which includes the following:

LED Combine Enables an LED to display the status for a combination of primary and secondary 
modes. This can be enabled or disabled for each LED pin. For example, a copper link running in 
1000BASE-T mode and activity present can be displayed with one LED by configuring an LED pin to 
Link1000/Activity mode. The LED asserts when linked to a 1000BASE-T partner and also blinks or 
performs pulse-stretch when activity is either transmitted by the PHY or received by the Link Partner. 
When disabled, the combine feature only provides status of the selected primary function. In this 
example, only Link1000 asserts the LED, and the secondary mode, activity, does not display if the 
combine feature is disabled.

LED Blink or Pulse-Stretch This behavior is used for activity and collision indication. This can be 
uniquely configured for each LED pin. Activity and collision events can occur randomly and intermittently 
throughout the link-up period. Blink is a 50% duty cycle oscillation of asserting and de-asserting an LED 

11 100BASE-FX/
1000BASE-X Fiber 
Activity

1 = No 100BASE-FX or 1000BASE-X activity present.
Blink or pulse-stretch = 100BASE-FX or 1000BASE-X activity present (becomes 
RX activity present if register bit 30.14 is set to 1).

12 Auto-Negotiation Fault 1 = No auto-negotiation fault present.
0 = Auto-negotiation fault occurred.

13 Serial Mode Serial stream = See Serial LED Mode, page 20. Only relevant on PHY port 0 and 
reserved in others.

14 Force LED Off 1 = De-asserts the LED(2).

15 Force LED On 0 = Asserts the LED(2).

1. Link/Activity can be configured to only display copper link and disable fiber link status by setting register bits 30.15 to 1.
2. Setting this suppresses the LED blink after reset.

Table 5 • Extended LED Mode and Function Summary

Mode Function Name LED State and Description
16 Link1000BASE-X Activity 1 = No link in 1000BASE-X.

0 = Valid 1000BASE-X link.

17 Link100BASE-FX Activity 1 = No link in 100BASE-FX.
0 = Valid 100BASE-FX link.

18 1000BASE-X Activity 1 = No 1000BASE-X activity present.
Blink or pulse-stretch = 1000BASE-X activity present

19 100BASE-FX Activity 1 = No 100BASE-FX activity present.
Blink or pulse-stretch = 100BASE-FX activity present

20 Force LED Off 1 = De-asserts the LED.

21 Force LED On 0 = Asserts the LED. LED Pulsing is disabled with this mode.

Table 4 • LED Mode and Function Summary (continued)

Mode Function Name LED State and Description



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 20

pin. Pulse-stretch guarantees that an LED is asserted and de-asserted for a specific period of time when 
activity is either present or not present. These rates can also be configured using a register setting.

Rate of LED Blink or Pulse-Stretch This behavior controls the LED blink rate or pulse-stretch length 
when blink/pulse-stretch is enabled on an LED pin. The blink rate, which alternates between a high and 
low voltage level at a 50% duty cycle, can be set to 2.5 Hz, 5 Hz, 10 Hz, or 20 Hz. For pulse-stretch, the 
rate can be set to 50 ms, 100 ms, 200 ms, or 400 ms. The blink rate selection for PHY0 globally sets the 
rate used for all LED pins on all PHY ports.

LED Pulsing Enable To provide additional power savings, the LEDs (when asserted) can be pulsed at 
5 kHz, 20% duty cycle.

LED Blink After Reset The LEDs will blink for one second after power-up and after any time all resets 
have been de-asserted. This can be disabled through register 19E, bit 11 = 0.

Fiber LED Disable This bit controls whether the LEDs indicate the Fiber and Copper status (default) or 
the Copper status only.

3.14.4 Serial LED Mode
Optionally, the VSC8662 device can be configured so that access to all its LED signals is available 
through two pins. This option is enabled by setting LED0 on PHY0 to Serial LED mode. When the mode 
is enabled on PHY0, the device LED0_0 pin becomes the serial data pin and the LED1_0 pin becomes 
the serial clock pin. All other LED pins can still be configured normally. The Serial LED mode clocks the 
48 LED status bits on the rising edge of the serial clock. Between each cycle of 48 bits, there is a 25 ms 
pause. To initialize synchronization, wait until after the first pause, after which the data becomes valid, 
before sampling the data on the falling edge of the serial clock. For more information about the LED clock 
and data timing relationship, see Figure 24, page 75.

The LED behavior settings (in device register 30) can also be used in Serial LED Mode. The controls are 
used on a per-PHY basis, where the LED combine and LED blink or pulse-stretch setting of LED0_n for 
each PHY is used to control the behavior of each bit of the serial LED stream for each corresponding 
PHY.

The serial bitstream outputs, 1 through 48, of each LED signal are shown in the following table beginning 
with PHY port 0 and ending with 24 reserved bits. The individual signals can be clocked in the order 
shown. 

Table 6 • LED Serial Stream Order

PHY0 PHY1
Bit 1. Link/Activity Bit 13. Link/Activity Bit 25. Reserved Bit 37. Reserved

Bit 2. Link1000/
Activity

Bit 14. Link1000/
Activity

Bit 26. Reserved Bit 38. Reserved

Bit 3. Link100/
Activity

Bit 15. Link100/
Activity

Bit 27. Reserved Bit 39. Reserved

Bit 4. Link10/
Activity

Bit 16. Link10/
Activity

Bit 28. Reserved Bit 40. Reserved

Bit 5. Fiber Link/Activity Bit 17. Fiber Link/Activity Bit 29. Reserved Bit 41. Reserved

Bit 6. Duplex/
Collision

Bit 18. Duplex/
Collision

Bit 30. Reserved Bit 42. Reserved

Bit 7. Collision Bit 19. Collision Bit 31. Reserved Bit 43. Reserved

Bit 8. Activity Bit 20. Activity Bit 32. Reserved Bit 44. Reserved

Bit 9. Fiber Activity Bit 21. Fiber Activity Bit 33. Reserved Bit 45. Reserved

Bit 10. TX Activity Bit 22. TX Activity Bit 34. Reserved Bit 46. Reserved

Bit 11. RX Activity Bit 23. RX Activity Bit 35. Reserved Bit 47. Reserved



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 21

3.14.5 LED Port Swapping
For additional hardware configuration, the VSC8662 can have its LED ports swapped. This is useful 
feature to help simplify PCB layout design. Register 15G bit0 controls the LED port swapping mode 
based on the following table. 

3.15 Integrated Two-Wire Serial Multiplexer
The VSC8662 device includes an integrated dual two-wire serial multiplexer (mux), eliminating the need 
for an external two-wire serial device for the control and status of SFP or PoE modules. There are three 
two-wire serial controller pins: tour clocks and one shared data pin. Each SFP or PoE connects to their 
corresponding SCL clock pin and shares the SDA data pin, as shown in Figure 13, page 21. 

For SFP modules, the VSC8662 device can also provide control for the module_detect and TX_DIS pins. 
To establish control of the SFP module_detect pins, use the VSC8662 GPIO[15:9] and GPIO[3:0] pins. 
For control of the SFP TX_DIS pins, use the VSC8662 LED pins in the force LED on and off modes.

Figure 13 • Example of Using Two-Wire Serial Mux with SFP Control and Status

3.15.1 Read/Write Access Using the Two-Wire Serial Mux
The VSC8662 device using the integrated two-wire serial mux can read and write to an SFP or PoE 
module through the SCL and SDA pins. If the ability is required to write to the slave two-wire serial 
device, refer to the device’s specific datasheet for more information. Also note that the VSC8662 device 
does not automatically increment the two-wire serial address; each desired address must be intentionally 
set.

Bit 12. Auto-Negotiation 
Fault

Bit 24. Auto-Negotiation 
Fault

Bit 36. Reserved Bit 48. Reserved

Table 7 • LED Port Swapping Table

PHY Mode 0 - default Mode 1
Port 0 LEDs from Port 0 LEDs from Port 1

Port 1 LEDs from Port 1 LEDs from Port 0

Table 6 • LED Serial Stream Order (continued)

PHY0 PHY1

Integrated
I2C Mux

Management
Interface

MDC
MDIO

SDA
SCL SFP 0

SDA
SCL SFP 1

I2C_SCL_0
I2C_SCL_1

I2C_SDA

PHY



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 22

Main control of the integrated two-wire serial mux is available through register 20G. The two-wire serial 
mux pins are enabled or disabled using register 20G.3:0 (by default, the pins are GPIO). Register 
20G.15:9 sets the two-wire serial device address (the default is 0xA0). Using register 20G.5:4, the two-
wire serial frequency can be changed from 100 kHz to other speeds, such as 50 kHz, 100 kHz (the 
default), 400 kHz, and 2 MHz. 

Registers 21G and 22G provide status and control of the read/write process. The following illustration 
depicts the read and write register flow.

Figure 14 • Two-Wire Serial Mux Read and Write Register Flow

To read a value from a specific address of the two-wire serial slave device:

7. Read the VSC8662 device register bit 21G.15, and ensure that it is set.
8. Write the PHY port address to be read to register bit 21G.10.
9. Write the two-wire serial address to be read to register bits 21G.7:0.
10. Set both register bits 21G.8 and 21G.9 to 1.
11. When register bit 21G.15 changes to 1, read the 8-bit data value found at register bits 22G.15:8. This 

is the contents of the address just read by the PHY.
To write a value to a specific address of the two-wire serial slave device:

12. Read the VSC8662 device register bit 21G.15 and ensure that it is set.
13. Write the PHY port address to be written to register bit 21G.10.
14. Write the address to be written to register bits 21G.7:0.
15. Set register bit 21G.8 to 0.
16. Set register bits 22G.7:0 with the 8-bit value to be written to the slave device.
17. Set register bit 21G.9 to 1. 
To avoid collisions during read and write transactions on the two-wire serial bus, always wait until register 
bit 21G.15 changes to 1 before performing another two-wire serial read or write operation.

3.16 GPIO Pins
The VSC8662 device provides up to ten dedicated general-purpose input/output (GPIO) pins. In addition, 
the fast link failover indication pin, two device SIGDET pins, and three two-wire serial mux control pins 
can also be configured as GPIO pins, resulting in a total of 16 GPIO pins.

All device GPIO pins and their behavior are controlled using registers. For more information, see 
General-Purpose I/O Registers, page 56.

Wait for Ready

21G.15 = 0

21G.15 = 1

Read or Write

21G.10 = PHY Port t o Write
21G.7:0 = Write Address

21G.8 = 0
22G.7:0 = Data  to Write

Write SFP
Data

= PHY Port to Read
21G.7:0 = Address to Read

21G.8 = 1

21G.9 = 1

21G.9 = 1

Wait for Ready

21G.15 = 0

21G.15 = 1

Read SFP
Data

Read Data = 22G.15:8

Start

21G.10



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 23

3.17 Testing Features
The VSC8662 device includes several testing features designed to make it easier to perform system-
level debugging and in-system production testing. This section describes the available features.

3.17.1 Ethernet Packet Generator (EPG)
The device EPG can be used at each of the 10/100/1000BASE-T speed settings for Copper Cat5 media 
and fiber media to isolate problems between the MAC and the VSC8662 device, or between a locally 
connected PHY and its remote link partner. Enabling the EPG feature effectively disables all MAC 
interface transmit pins and selects the EPG as the source for all data transmitted onto the twisted pair 
interface.This feature is not used when the SerDes media is set to pass-through mode.

Important The EPG is intended for use with laboratory or in-system testing equipment only. Do not use 
the EPG testing feature when the VSC8662 device is connected to a live network.

To enable the VSC8662 device EPG feature, set the device register bit 29E.15 to 1.

When the EPG is enabled, packet loss occurs during transmission of packets from the MAC to the PHY. 
However, the PHY receive output pins to the MAC are still active when the EPG is enabled. If it is 
necessary to disable the MAC receive pins as well, set the register bit 0.10 to 1.

When the device register bit 29E.14 is set to 1, the PHY begins transmitting Ethernet packets based on 
the settings in registers 29E and 30E. These registers set:

• Source and destination addresses for each packet
• Packet size
• Inter-packet gap
• FCS state
• Transmit duration
• Payload pattern
If register bit 29E.13 is set to 0, register bit 29E.14 is cleared automatically after 30,000,000 packets are 
transmitted.

3.17.2 CRC Counters
Two separate cyclical redundancy checking (CRC) counters are available on all PHYs in the VSC8662 
device and resides between the FIFO and SerDes MAC interface. There is a 14-bit good CRC counter 
available in register bits 18E.13:0 and a separate 8-bit bad CRC counter available in register bits 
23E.7:0.

The device CRC counters operate in the 100BASE-FX/1000BASE-X over SerDes mode as well as in the 
10/100/1000BASE-T mode testing as follows:

• After receiving a packet on the media interface, register bit 18E.15 is set and cleared after being 
read. The packet then is counted by either the good CRC counter or the bad CRC counter. Both 
CRC counters are also automatically cleared when read.

• The good CRC counter’s highest value is 9,999 packets. After this value is reached, the counter 
clears on the 10,000th packet and continues to count additional packets beyond that value. The bad 
CRC counter stops counting when it reaches its maximum counter limit of 255 packets.

3.17.3 Far-End Loopback
The far-end loopback testing feature is enabled by setting register bit 23.3 to 1. When enabled, it forces 
incoming data from a link partner on the current media interface, into the MAC interface of the PHY, to be 
retransmitted back to the link partner on the media interface as shown in the following illustration. In 
addition, the incoming data also appears on the receive data pins of the MAC interface. Data present on 
the transmit data pins of the MAC interface is ignored when using this testing feature.



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 24

Figure 15 • Far-End Loopback Diagram

3.17.4 Near-End Loopback
When the near-end loopback testing feature is enabled (by setting the device register bit 0.14 to 1), data 
on the transmit data pins (TXD) is looped back in the PCS block, onto the device receive data pins 
(RXD), as shown in the following figure. When using this testing feature, no data is transmitted over the 
network.

Figure 16 • Near-End Loopback Diagram

3.17.5 Connector Loopback
The connector loopback testing feature allows the twisted pair interface to be looped back externally. 
When using this feature, the PHY must be connected to a loopback connector or a loopback cable. Pair 
A should be connected to pair B, and pair C to pair D, as shown in the following figure. The connector 
loopback feature functions at all available interface speeds.

Figure 17 • Connector Loopback Diagram

When using the connector loopback testing feature, the device auto-negotiation, speed, and duplex 
configuration is set using device registers 0, 4, and 9. For 1000BASE-T connector loopback, the 
following additional writes are required. Execute the additional writes in the following order:

18. Enable the 1000BASE-T connector loopback. Set register bit 24.0 to 1.
19. Disable pair swap correction. Set register bit 18.5 to 1.

3.17.6 SerDes Loopbacks
The SerDes loopback testing feature allows a user to ensure connectivity between the MAC or SerDes 
Link Partner and the PHY. There are several different SerDes loopbacks available, which can help debug 
SerDes link issues with a MAC/switch/ASIC or with a SerDes media link partner. In terms of clock 
reference, all three loopbacks are based on the clock from the link partner. You also have the option to 
not loopback the data and instead use the recovered clock instead of the clock based on REFCLK. This 
is useful for debugging the MAC transmitter clock’s performance. Register 19E.10:8 sets the specific 
SerDes loopback for the media interface. To enable the media interface loopback, set register 19E.10 to 

Link Partner PHY_Port_n MACRX

TX

RXD

TXD

Cat5

Link Partner PHY Port_n MACRX

TX

RXD

TXD

Cat5

PHY Port_n MAC

RXD

TXD

Cat5

A

B

C

D



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 25

1. Register 19E.6:5 sets the specific SerDes loopback for the MAC interface. To enable the MAC 
interface loopback, set register 19E.7 to 1.

Figure 18 • SerDes Loopbacks

3.17.7 VeriPHY Cable Diagnostics
The VSC8662 device includes a comprehensive suite of cable diagnostic functions that are available 
using SMI reads and writes. These functions enable a variety of cable operating conditions and status to 
be accessed and checked. The VeriPHY suite has the ability to identify the cable length and the 
operating conditions and to isolate the common faults that can occur on the Cat5 twisted pair cabling.

For the functional details of the VeriPHY suite and the operating instructions, see the ENT-AN0125, PHY, 
Integrated PHY-Switch VeriPHY - Cable Diagnostics Feature Application Note.

3.17.8 IEEE 1149.1 JTAG Boundary Scan
The VSC8662 device supports the test access port (TAP) and Boundary Scan Architecture described in 
the IEEE standard 1149.1. The device includes an IEEE 1149.1-compliant test interface, often referred to 
as a “JTAG TAP Interface.” 

The JTAG boundary scan logic on the VSC8662 device, accessed using its TAP interface, consists of a 
boundary scan register and other logic control blocks. The TAP controller includes all IEEE-required 
signals (TMS, TCK, TDI, and TDO), in addition to the optional asynchronous reset signal NTRST.

The following illustration shows the TAP and Boundary Scan Architecture.

Deserializer
Shift Register

SerDes Input +
SerDes RX Buffer

SerDes Input –

+

SerDes Output +

SerDes TX Buffer
SerDes Output –

+

–

SerDes Pad 
Loopback

Serializer
Shift Register

SerDes Serial 
Loopback

Parallel-to-Serial

Receive PCS

Transmit PCS

SerDes Parallel 
Loopback

10

10

Serial-to-Parallel
Comma Aligned–



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 26

Figure 19 • Test Access Port and Boundary Scan Architecture Diagram

After a TAP reset, the device identification register is serially connected between TDI and TDO by 
default. The TAP instruction register is loaded either from a shift register (when a new instruction is 
shifted in) or, if there is no new instruction in the shift register, a default value of 0110 (IDCODE) is 
loaded. Using this method, there is always a valid code in the instruction register, and the problem of 
toggling instruction bits during a shift is avoided. Unused codes are mapped to the BYPASS instruction.

3.17.9 JTAG Instruction Codes
The VSC8662 device supports the following instruction codes:

EXTEST Allows tests of the off-chip circuitry and board-level interconnections by sampling input pins 
and loading data onto output pins. Outputs are driven by the contents of the boundary-scan cells, which 
have to be updated with valid values (with the PRELOAD instruction) prior to the EXTEST instruction.

SAMPLE/PRELOAD Allows a snapshot of inputs and outputs during normal system operation to be 
taken and examined. It also allows data values to be loaded into the boundary-scan cells prior to the 
selection of other boundary-scan test instructions.

IDCODE Provides the version number (bits 31:28), part number (bits 27:12), and the manufacturer 
identity (bits 11:1) to be serially read from the device.

The following table provides information about the meaning of IDCODE binary values stored in the 
device JTAG registers. 

Table 8 • JTAG Device Identification Register Description

Description
Device Version 
Number Model Number

Manufacturing 
Identity LSB

Bit field 31 through 28 27 through 12 11 through 1 0

Binary value 00000 1000 0110 0110 0100 001 1001 1000 1

Boundary-Scan
Register

Device Identification
Register

Bypass Register

Instruction Register,
Instruction Decode,

Control

Test Access Port
ControllerNTRST

TMS

TDI

TCK

Select

Control

TDO Enable

Control Mux,
DFF

TDO



Functional Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 27

CLAMP Allows the state of the signals driven from the component pins to be determined from the 
boundary scan register while the bypass register is selected as the serial path between TDI and TDO. 
While the CLAMP instruction is selected, the signals driven from the component pins do not change.

HIGHZ Places the component in a state in which all of its system logic outputs are placed in a high-
impedance state. In this state, an in-circuit test system may drive signals onto the connections normally 
driven by a component output without incurring a risk of damage to the component. This makes it 
possible to use a board where not all of the components are compatible with the IEEE 1149.1 standard.

BYPASS The bypass register contains a single shift-register stage and is used to provide a minimum-
length serial path (one TCK clock period) between TDI and TDO to bypass the device when no test 
operation is required.

The following table provides more information about the location and IEEE compliance of the JTAG 
instruction codes used in the VSC8662. For more information about these IEEE specifications, visit the 
IEEE Web site at www.IEEE.org.

3.17.10 Boundary Scan Register Cell Order
All inputs and outputs are observed in the boundary scan register cells. All outputs are additionally driven 
by the contents of boundary scan register cells. Bidirectional pins have all three related boundary scan 
register cells: input, output, and control.

The complete boundary scan cell order is available as a BSDL file format on the Vitesse Web site at 
www.vitesse.com.

3.17.11 IEEE 1149.6 AC-JTAG Boundary Scan Interface
The IEEE 1149.6 AC-JTAG solution integrated on all SerDes ports of the VSC8662 device extends the 
capability of IEEE 1149.1 boundary scan for robust board-level testing. This interface is backward-
compatible to the IEEE 1149.1 standard.

Table 9 • JTAG Interface Instruction Codes

Instruction Code Selected Register
Register 
Width

IEEE 1149.1
Specification

IEEE 1149.6 
Specification

EXTEST 0000 Boundary-Scan 161 Mandatory

SAMPLE/PRELOA
D

0001 Boundary-Scan 161 Mandatory

IDCODE 0110 Device Identification 32 Optional

CLAMP 0010 Bypass Register 1 Optional

HIGHZ 0011 Bypass Register 1 Optional

BYPASS 1111 Bypass Register 1 Mandatory

EXTEST_PULSE 0100 Boundary-Scan Register 161 Mandatory

EXTEST_TRAIN 0101 Boundary-Scan Register 161 Mandatory

RESERVED 0111,
1000 through 
1110



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 28

4 Configuration

The VSC8662 device can be configured using two different methods:

• Setting internal memory registers using the management interface
• Setting a combination of CMODE pins and registers

4.1 Registers
This section provides information about how to configure the VSC8662 device using its internal memory 
registers and the management interface. For information about configuring the device using the CMODE 
pins, see CMODE, page 61.

The VSC8662 device uses three types of registers: 

• IEEE standard and main device registers with addresses from 0 to 31
• Extended registers with addresses from 16E through 30E
• General-purpose input and output (GPIO) registers with addresses from 0G to 30G
The following illustration shows the relationship between the device registers and their address spaces.

Figure 20 • Register Space Diagram

4.1.1 Reserved Registers
For main registers 16 through 31, extended registers 16E through 30E, and GPIO registers 0G through 
30G, any bits marked as “Reserved” should be processed as read only and their states as undefined.

IEEE 802.3 
Standard Registers

Extended RegistersMain Registers

0x0000 0x000131

0
1
2
3
.
.
.
.
.
.
.
.

15

16
17
18
19
.
.
.
.
.
.
.
.

30

GPIO Registers

0x0010

0G
1G
2G
3G
.
.
.
.
.
.
.
.

15G
16G

.

.

.

.

.

.

.

.

.

.

.
30G

16E
17E
18E
19E

.

.

.

.

.

.

.

.
30E



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 29

4.1.2 Reserved Bits
In writing to registers with reserved bits, use a “read-modify-then-write” technique, where the entire 
register is read but only the intended bits to be changed are modified. Reserved bits cannot be changed 
and their read state cannot be considered static or unchanging.

4.2 IEEE Standard and Main Registers 
In the VSC8662 device, the page space of the standard registers consists of the IEEE standard registers 
and the Vitesse standard registers. The following table lists the names of the registers associated with 
the addresses as dictated by the IEEE standard. 

The following table lists the names of the registers in the main page space of the device. These registers 
are accessible only when register address 31 is set to 0x0000. 

Table 10 • IEEE 802.3 Standard Registers

Register Address Register Name
0 Mode control

1 Mode status

2 PHY identifier 1

3 PHY identifier 2

4 Auto-negotiation advertisement 

5 Auto-negotiation link partner ability 

6 Auto-negotiation expansion 

7 Auto-negotiation next-page transmit 

8 Auto-negotiation link partner next-page receive 

9 1000BASE-T control 

10 1000BASE-T status 

11 Reserved

12 Reserved

13 Reserved

14 Reserved

15 1000BASE-T status extension 1

Table 11 • Main Registers

Register Address Register Name
16 100BASE-TX status extension 

17 1000BASE-T status extension 2

18 Bypass control

19 Error Counter 1

20 Error Counter 2

21 Error Counter 3

22 Extended control and status

23 Extended PHY control 1

24 Extended PHY control 2



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 30

4.2.1 Mode Control
The device register at memory address 0 controls several aspects of VSC8662 functionality. The 
following table shows the available bit settings in this register and what they control.

25 Interrupt mask

26 Interrupt status

27 MAC interface auto-negotiation control and status

28 Auxiliary control and status

29 LED mode select

30 LED behavior

31 Extended register page access

Table 12 • Mode Control, Address 0 (0x00)

Bit Name Access Description Default
15 Software reset R/W This is a self-clearing bit that restores all 

serial management interface (SMI) registers 
to their default state, except for sticky and 
super sticky bits.
1 = Reset asserted.
0 = Reset de-asserted.
You must wait 4 µs after setting this bit to 
initiate another SMI register access.

0

14 Loopback R/W 1 = Loopback enabled.
0 = Loopback disabled.
When loop back is enabled, the device 
functions at the current speed setting and 
with the current duplex mode setting (bit 8 of 
this register).

0

13 LSB for speed 
selection

R/W See bit 6 below. 0

12 Auto-negotiation 
enable

R/W 1 = Auto-negotiation enabled.
0 = Auto-negotiation disabled.

1

11 Power-down R/W 1 = Power-down enabled. 0

10 Isolate R/W 1 = Disable MAC interface outputs and ignore 
MAC interface inputs.

0

9 Restart auto-
negotiation

R/W This is a self-clearing bit.
1 = Restart auto-negotiation on media 
interface.

0

8 Duplex R/W  1 = Full-duplex.
 0 = Half-duplex.

0

7 Collision test enable R/W  1 = Collision test enabled. 0

6, 13 Forced speed 
selection

R/W MSB = bit 6, LSB = bit 13.
00 = 10 Mbps.
01 = 100 Mbps.
10 = 1000 Mbps.
11 = Reserved.

10

Table 11 • Main Registers (continued)

Register Address Register Name



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 31

Note: Bit 5 is only applicable to 100BASE-FX and 1000BASE-X fiber media.

4.2.2 Mode Status
The register at address 1 in the device main registers space allows you to read the currently enabled 
mode setting. The following table shows possible readouts of this register.

5 Unidirectional enable R/W When bit 0.12 = 1 or bit 0.8 = 0, this bit is 
ignored.
When bit 0.12 = 0 and bit 0.8 = 1, the 
behavior is as follows:
1 = Enable transmit from media independent 
interface regardless of whether the PHY has 
determined that a valid link has been 
established.
0 = Enable transmit from media independent 
interface only when the PHY has determined 
that a valid link has been established.

0

0 Reserved 00000

Table 13 • Mode Status, Address 1 (0x01)

Bit Name Access Description Default
15 100BASE-T4 

capability
RO 1 = 100BASE-T4 capable. 0

14 100BASE-TX FDX 
capability

RO 1 = 100BASE-TX FDX capable. 1

13 100BASE-TX HDX 
capability

RO 1 = 100BASE-TX HDX capable. 1

12 10BASE-T FDX 
capability

RO 1 = 10BASE-T FDX capable. 1

11 10BASE-T HDX 
capability

RO 1 = 10BASE-T HDX capable. 1

10 100BASE-T2 FDX 
capability

RO 1 = 100BASE-T2 FDX capable. 0

9 100BASE-T2 HDX 
capability

RO 1 = 100BASE-T2 HDX capable. 0

8 Extended status 
enable

RO 1 = Extended status information present in 
register 15.

1

7 Unidirectional ability RO 1 = PHY able to transmit from media 
independent interface regardless of whether 
the PHY has determined that a valid link has 
been established.
0 = PHY able to transmit from media 
independent interface only when the PHY has 
determined that a valid link has been 
established.

1

6 Preamble 
suppression 
capability

RO 1 = MF preamble may be suppressed.
0 = MF always required.

1

Table 12 • Mode Control, Address 0 (0x00) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 32

Note: Bit 7 is only applicable to 100BASE-FX and 1000BASE-X fiber media

4.2.3 Device Identification
All 16 bits in both register 2 and register 3 in the VSC8662 device are used to provide information 
associated with aspects of the device identification. The following tables list the readouts you can expect. 

4.2.4 Auto-Negotiation Advertisement
The bits in address 4 in the main registers space control the VSC8662 device ability to notify other 
devices of the status of its auto-negotiation feature. The following table shows the available settings and 
readouts. 

5 Auto-negotiation 
complete

RO 1 = Auto-negotiation complete. 0

4 Remote fault RO This bit latches high. 
1 = Far-end fault detected.

0

3 Auto-negotiation 
capability

RO 1 = Auto-negotiation capable. 1

2 Link status RO This bit latches low.
1 = Link is up.

0

1 Jabber detect RO This bit latches high.
1 = Jabber condition detected.

0

0 Extended capability RO 1 = Extended register capable. 1

Table 14 • Identifier 1, Address 2 (0x02)

Bit Name Access Description Default
15:0 Organizationally unique 

identifier (OUI)
RO OUI most significant bits (3:18) 0x0007

Table 15 • Identifier 2, Address 3 (0x03)

Bit Name Access Description Default
15:10 OUI RO OUI least significant bits (19:24) 0x0001

9:4 Vitesse model number RO VSC8662 (0×26) 100110

3:0 Device revision number RO 0000

Table 16 • Device Auto-Negotiation Advertisement, Address 4 (0x04)  

Bit Name Access Description Default
15 Next page transmission 

request
R/W 1 = Request enabled 0

14 Reserved RO 0

13 Transmit remote fault R/W 1 = Enabled 0

12 Reserved R/W 0

11 Advertise asymmetric 
pause

R/W 1 = Advertises asymmetric pause CMODE

Table 13 • Mode Status, Address 1 (0x01) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 33

4.2.5 Link Partner Auto-Negotiation Capability
The bits in main register 5 enable you to determine if the Cat5 link partner (LP) used with the VSC8662 
device is compatible with the auto-negotiation functionality. 

10 Advertise symmetric 
pause

R/W 1 = Advertises symmetric pause CMODE

9 Advertise
100BASE-T4

R/W 1 = Advertises 100BASE-T4 0

8 Advertise
100BASE-TX FDX

R/W 1 = Advertise 100BASE-TX FDX CMODE

7 Advertise
100BASE-TX HDX

R/W 1 = Advertises 100BASE-TX HDX CMODE

6 Advertise
10BASE-T FDX

R/W 1 = Advertises 10BASE-T FDX CMODE

5 Advertise
10BASE-T HDX

R/W 1 = Advertises 10BASE-T HDX CMODE

4:0 Advertise selector R/W 00001

Table 17 • Auto-Negotiation Link Partner Ability, Address 5 (0x05)

Bit Name Access Description Default
15 LP next page 

transmission request
RO 1 = Requested 0

14 LP acknowledge RO 1 = Acknowledge 0

13 LP remote fault RO 1 = Remote fault 0

12 Reserved RO 0

11 LP advertise 
asymmetric pause

RO 1 = Capable of asymmetric pause 0

10 LP advertise 
symmetric pause

RO 1 = Capable of symmetric pause 0

9 LP advertise 
100BASE-T4

RO 1 = Capable of 100BASE-T4 0

8 LP advertise 
100BASE-TX FDX

RO 1 = Capable of 100BASE-TX FDX 0

7 LP advertise 
100BASE-TX HDX

RO 1 = Capable of 100BASE-TX HDX 0

6 LP advertise 
10BASE-T FDX

RO 1 = Capable of 10BASE-T FDX 0

5 LP advertise 
10BASE-T HDX

RO 1 = Capable of 10BASE-T HDX 0

4:0 LP advertise selector RO 00000

Table 16 • Device Auto-Negotiation Advertisement, Address 4 (0x04) (continued) 

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 34

4.2.6 Auto-Negotiation Expansion
The bits in main register 6 work together with those in register 5 to indicate the status of the LP auto-
negotiation functioning. The following table shows the available settings and readouts. 

4.2.7 Transmit Auto-Negotiation Next Page
The settings in register 7 in the main registers space provide information about the number of pages in 
an auto-negotiation sequence. The following table shows the settings available. 

4.2.8 Auto-Negotiation Link Partner Next Page Receive
The bits in register 8 of the main register space work together with register 7 to determine certain aspects 
of the LP auto-negotiation. The following table shows the possible readouts. 

Table 18 • Auto-Negotiation Expansion, Address 6 (0x06)

Bit Name Access Description Default
15:5 Reserved RO 00000000000

4 Parallel detection fault RO This bit latches high.
1 = Parallel detection fault.

0

3 LP next page capable RO 1 = LP is next page capable. 0

2 Local PHY next page 
capable

RO 1 = Local PHY is next page capable. 1

1 Page received RO This bit latches low.
1 = New page is received.

0

0 LP is auto-negotiation 
capable

RO 1 = LP is capable of auto-negotiation. 0

Table 19 • Auto-Negotiation Next Page Transmit, Address 7 (0x07)

Bit Name Access Description Default
15 Next page R/W 1 = More pages follow 0

14 Reserved RO 0

13 Message page R/W 1 = Message page
0 = Unformatted page

1

12 Acknowledge 2 R/W 1 = Complies with request
0 = Cannot comply with request

0

11 Toggle RO 1 = Previous transmitted LCW = 0
0 = Previous transmitted LCW = 1

0

10:0 Message 
/unformatted code

R/W 00000000
001

Table 20 • Auto-Negotiation LP Next Page Receive, Address 8 (0x08)

Bit Name Access Description Default
15 LP next page RO 1 = More pages follow 0

14 Acknowledge RO 1 = LP acknowledge 0

13 LP message page RO 1 = Message page
0 = Unformatted page

0

12 LP Acknowledge 2 RO 1 = LP complies with request 0



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 35

4.2.9 1000BASE-T Control
The VSC8662 device’s 1000BASE-T functionality is controlled by the bits in register 9 of the main 
register space. The following table shows the settings and readouts available. 

Note: Transmitter Test mode (bits 15:13) operates in the manner described in IEEE standard 802.3, section 
40.6.1.1.2. When using any of the Transmitter Test modes, the Auto-Media Sense functionality must be 
disabled. For more information, see Extended PHY Control Set 1, page 40.

4.2.10 1000BASE-T Status
The bits in register 10 of the main register space allow you to read the status of the 1000BASE-T 
communications enabled in the device. The following table shows the readouts. 

11 LP toggle RO 1 = Previous transmitted LCW = 0
0 = Previous transmitted LCW = 1

0

10:0 LP message 
/unformatted code

RO 00000000000

Table 21 • 1000BASE-T Control, Address 9 (0x09)

Bit Name Access Description Default
15:13 Transmitter test 

mode
R/W 000 = Normal.

001 = Mode 1: Transmit waveform test.
010 = Mode 2: Transmit jitter test as master.
011 = Mode 3: Transmit jitter test as slave.
100 = Mode 4: Transmitter distortion test.
101 to 111 = Reserved: Operation not defined.

000

12 Master/slave 
manual 
configuration

R/W 1 = Master/slave manual configuration enabled. 0

11 Master/slave 
value

R/W This register is only valid when bit 9.12 is set to 1.
1 = Configure PHY as master during negotiation.
0 = Configure PHY as slave during negotiation.

0

10 Port type R/W 1 = Multi-port device.
0 = Single-port device.

1

9 1000BASE-T 
FDX capability

R/W 1 = PHY is 1000BASE-T FDX capable. CMODE

8 1000BASE-T 
HDX capability

R/W 1 = PHY is 1000BASE-T HDX capable. CMODE

7:0 Reserved R/W 0x00

Table 22 • 1000BASE-T Status, Address 10 (0x0A)

Bit Name Access Description Default
15 Master/slave 

configuration fault
RO This bit latches high.

1 = Master/slave configuration fault detected.
0 = No master/slave configuration fault 
detected.

0

Table 20 • Auto-Negotiation LP Next Page Receive, Address 8 (0x08) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 36

4.2.11 1000BASE-T Status Extension 1
Register 15 provides additional information about the operation of the device 1000BASE-T 
communications. The following table shows the readouts available. 

4.2.12 100BASE-TX Status Extension
Register 16 in the main registers page space of the VSC8662 device provides additional information 
about the status of the device’s 100BASE-TX operation. 

14 Master/slave 
configuration 
resolution

RO 1 = Local PHY configuration resolved to 
master.
0 = Local PHY configuration resolved to slave.

1

13 Local receiver status RO 1 = Local receiver is operating normally. 0

12 Remote receiver 
status

RO 1 = Remote receiver OK. 0

11 LP 1000BASE-T FDX 
capability

RO 1 = LP 1000BASE-T FDX capable. 0

10 LP 1000BASE-T HDX 
capability

RO 1 = LP 1000BASE-T HDX capable. 0

9:8 Reserved RO 00

7:0 Idle error count RO This is a self-clearing bit. 0x00

Table 23 • 1000BASE-T Status Extension 1, Address 15 (0x0F)

Bit Name Access Description Default
15 1000BASE-X FDX 

capability
RO 1 = PHY is 1000BASE-X FDX capable 0

14 1000BASE-X HDX 
capability

RO 1 = PHY is 1000BASE-X HDX capable 0

13 1000BASE-T FDX 
capability

RO 1 = PHY is 1000BASE-T FDX capable 1

12 1000BASE-T HDX 
capability

RO 1 = PHY is 1000BASE-T HDX capable 1

11:0 Reserved RO 0x000

Table 24 • 100BASE-TX Status Extension, Address 16 (0x10)

Bit Name Access Description Default
15 100BASE-TX 

Descrambler 
RO 1 = Descrambler locked. 0

14 100BASE-TX lock 
error

RO This is a self-clearing bit.
1 = Lock error detected.

0

13 100BASE-TX 
disconnect state

RO This is a self-clearing bit.
1 = PHY 100BASE-TX link disconnect 
detected.

0

12 100BASE-TX current 
link status

RO 1 = PHY 100BASE-TX link active. 0

Table 22 • 1000BASE-T Status, Address 10 (0x0A) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 37

4.2.13 1000BASE-T Status Extension 2
The second status extension register is at address 17 in the device main registers space. It provides 
information about another set of parameters associated with 1000BASE-T communications. For 
information about the first status extension register, see Table 24, page 36. 

11 100BASE-TX receive 
error

RO This is a self-clearing bit.
1 = Receive error detected.

0

10 100BASE-TX 
transmit error

RO This is a self-clearing bit.
1 = Transmit error detected.

0

9 100BASE-TX SSD 
error

RO This is a self-clearing bit.
1 = Start-of-stream delimiter error detected.

0

8 100BASE-TX ESD 
error

RO This is a self-clearing bit.
1 = End-of-stream delimiter error detected.

0

7:0 Reserved RO

Table 25 • 1000BASE-T Status Extension 2, Address 17 (0x11)

Bit Name Access Description Default
15 1000BASE-T 

descrambler 
RO 1 = Descrambler locked. 0

14 1000BASE-T lock 
error

RO This is a self-clearing bit.
1 = Lock error detected.

0

13 1000BASE-T 
disconnect state

RO This is a self-clearing bit.
1 = PHY 1000BASE-T link disconnect 
detected.

0

12 1000BASE-T current 
link status

RO 1 = PHY 1000BASE-T link active. 0

11 1000BASE-T receive 
error

RO This is a self-clearing bit.
1 = Receive error detected.

0

10 1000BASE-T transmit 
error

RO This is a self-clearing bit.
1 = Transmit error detected.

0

9 1000BASE-T SSD 
error

RO This is a self-clearing bit.
1 = Start-of-stream delimiter error detected.

0

8 1000BASE-T ESD 
error

RO This is a self-clearing bit.
1 = End-of-stream delimiter error detected.

0

7 1000BASE-T carrier 
extension error

RO This is a self-clearing bit.
1 = Carrier extension error detected.

0

6 Non-compliant 
BCM5400 detected

RO 1 = Non-compliant BCM5400 link partner 
detected.

0

5 MDI crossover error RO 1 = MDI crossover error was detected. 0

4:0 Reserved RO

Table 24 • 100BASE-TX Status Extension, Address 16 (0x10) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 38

4.2.14 Bypass Control
The bits in the Bypass Control register in the VSC8662 device control aspects of functionality in effect 
when the device is disabled so that traffic can bypass it in your design. The following table shows the 
settings available.

Note: If bit 18.1 is set to 1 in this register, automatic exchange of next pages is disabled, and control is returned 
to the user through the SMI after the base page is exchanged. The user then must send the correct 
sequence of next pages to the link partner, determine the common capabilities, and force the device into 
the correct configuration following the successful exchange of pages.

4.2.15 Error Counter 1
The bits in register 19 provide an error counter. The following table shows the settings available.

Table 26 • Bypass Control, Address 18 (0x12)

Bit Name Access Description Default
15 Transmit disable R/W 1 = PHY transmitter disabled. 0

14 4B5B 
encoder/decoder

R/W 1 = Bypass 4B/5B encoder/decoder. 0

13 Scrambler R/W 1 = Bypass scrambler. 0

12 De-scrambler R/W 1 = Bypass de-scrambler. 0

11 PCS receive R/W 1 = Bypass PCS receiver. 0

10 PCS transmit R/W 1 = Bypass PSC transmit. 0

9 LFI timer R/W 1 = Bypass Link Fail Inhibit (LFI) timer. 0

8 Reserved RO

7 HP Auto MDI/MDI-X 
at forced 10/100

R/W This is a sticky bit.
1 = Disable Auto MDI/MDI-X at forced 10/100 
speeds.

1

6 Non-compliant 
BCM5400 detect 
disable

R/W This is a sticky bit.
1 = Disable non-compliant BCM5400 
detection.

0

5 Disable pair swap 
correction

R/W This is a sticky bit.
1 = Disable the automatic pair swap correction.

0

4 Disable polarity 
correction

R/W This is a sticky bit.
1 = Disable polarity inversion correction on 
each subchannel.

0

3 Parallel detect control R/W This is a sticky bit.
1 = Do not ignore advertised ability.
0 = Ignore advertised ability.

1

2 Pulse shaping filter R/W 1 = Disable pulse shaping filter. 0

1 Disable automatic 
1000BASE-T next 
page exchange

R/W This is a sticky bit.
1 = Disable automatic 1000BASE-T next page 
exchanges.

0

0 CLKOUT output 
enable

R/W This is a sticky bit.
1 = Enable clock output pin.

CMODE

Table 27 • Extended Control and Status, Address 19 (0x13)

Bit Name Access Description Default
15:8 Reserved RO



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 39

4.2.16 Error Counter 2
The bits in register 20 provide an error counter. The following table shows the settings available.

4.2.17 Error Counter 3
The bits in register 21 provide an error counter. The following table shows the settings available.

4.2.18 Extended Control and Status
The bits in register 22 provide additional device control and readouts. The following table shows the 
settings available.

7:0 100BASE-TX/
1000BASE-T 
receive error 
counter

RO 8-bit counter that saturates when it reaches 
255. These bits are self-clearing when read.

0x00

Table 28 • Extended Control and Status, Address 20 (0x14)

Bit Name Access Description Default
15:8 Reserved RO

7:0 100BASE-TX/
1000BASE-T false 
carrier counter

RO 8-bit counter that saturates when it reaches 
255. These bits are self-clearing when read.

0x00

Table 29 • Extended Control and Status, Address 21 (0x15)

Bit Name Access Description Default
15:8 Reserved RO

7:0 Copper media link 
disconnect counter

RO 8-bit counter that saturates when it reaches 
255. These bits are self-clearing when read.

0x00

Table 30 • Extended Control and Status, Address 22 (0x16)

Bit Name Access Description Default
15 Force 10BASE-T 

link high
R/W This is a sticky bit.

1 = Bypass link integrity test.
0 = Enable link integrity test.

0

14 Jabber detect 
disable

R/W This is a sticky bit.
1 = Disable jabber detect.

0

13 Disable 10BASE-T 
echo

R/W This is a sticky bit.
1 = Disable 10BASE-T echo.

1

12 Disable SQE mode R/W This is a sticky bit.
1 = Disable SQE mode.

1

11:10 10BASE-T squelch 
control

R/W This is a sticky bit.
00 = Normal squelch.
01 = Low squelch.
10 = High squelch.
11 = Reserved.

00

Table 27 • Extended Control and Status, Address 19 (0x13) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 40

The following information applies to the extended control and status bits:

• When bit 22.15 is set, the link integrity state machine is bypassed and the PHY is forced into a link 
pass status. 

• When bits 22.11:10 are set to 00, the squelch threshold levels are based on the IEEE standard for 
10BASE-T. When set to 01, the squelch level is decreased, which may improve the bit error rate 
performance on long loops. When set to 10, the squelch level is increased and may improve the bit 
error rate in high-noise environments.

• When bit 22.9 is set, all sticky register bits retain their values during a software reset. Clearing this 
bit causes all sticky register bits to change to their default values upon software reset. Super-sticky 
bits retain their values upon software reset regardless of the setting of bit 22.9.

• When bit 22.0 is set, if a write to any PHY register (registers 0 through 31, including extended 
registers), the same write is broadcast to all PHYs. For example, if bit 22.0 is set to 1 and a write to 
PHY_0 is executed (register 0 is set to 0x1040), all PHYs’ register 0s are set to 0x1040. Disabling 
this bit restores normal PHY write operation. Reads are still possible when this bit is set, but the 
value that is read corresponds only to the particular PHY being addressed.

4.2.19 Extended PHY Control Set 1
The bits in the extended control set control the MAC auto-negotiation function, the SerDes functions, and 
report SGMII alignment errors. The following table shows the settings available. 

9 Sticky reset enable R/W This is a super-sticky bit.
1 = Enabled.

1

8 EOF Error RO This bit is self-clearing.
1 = EOF error detected.

0

7 10BASE-T 
disconnect state

RO This bit is self-clearing.
1 = 10BASE-T link disconnect detected.

0

6 10BASE-T link 
status

RO 1 = 10BASE-T link active. 0

5:3 Reserved RO

2:1 CRS control R/W Carrier sense control. The effect of each 
setting depends on whether it is half-duplex or 
full-duplex operation.

For half-duplex operation:
00 = Receiving + transmitting.
01 = Receiving + transmitting.
10 = Receiving.
11 = Receiving.

For full-duplex operation:
00 = Receiving.
01 = No carrier sensing.
10 = Receiving.
11 = No carrier sensing.

00

0 SMI broadcast 
write

R/W This is a sticky bit.
1 = Enabled.

0

Table 31 • Extended PHY Control 1, Address 23 (0x17)

Bit Name Access Description Default
15:14 Reserved RO

Table 30 • Extended Control and Status, Address 22 (0x16) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 41

Note: After configuring bits 13:8 of the extended PHY control register set 1, a software reset (register 0, bit 15) 
must be written to change the device operating mode. If bits 13:8 are read before the software reset has 
taken place, then the bits only indicate the actual operating mode and not the pending operating mode.

13 MAC interface 
auto-negotiation

R/W This is a super-sticky bit.
1 = Enabled.

CMODE

12 MAC interface mode R/W This is a super-sticky bit.
1 = 1000BASE-X.
0 = SGMII.

0

11 AMS preference R/W This is a super-sticky bit.
1 = Cat5 copper preferred.
0 = SerDes fiber/SFP preferred.

0

10:8 Media operating 
mode

R/W This is a super-sticky bit.
000 = Cat5 copper only.
001 = SerDes fiber/SFP pass-through mode 
only. No auto-negotiation performed in the 
PHY.
010 = 1000BASE-X fiber/SFP media only with 
auto-negotiation performed by the PHY.
011 = 100BASE-FX fiber/SFP on the fiber 
media pins only.
101 = Auto-Media Sense with Cat5 media or 
SerDes fiber/SFP pass-through mode.
110 = Auto-Media Sense with Cat5 media or 
1000BASE-X fiber/SFP media with auto-
negotiation performed by PHY.
111 = Auto-Media Sense with Cat5 media or 
100BASE-FX fiber/SFP media.
100 = Reserved.

CMODE

7:6 Force AMS override R/W 00 = Normal auto-media selection (AMS).
01 = Force AMS to select SerDes media only.
10 = Force AMS to select copper media only.
11 = Reserved.

00

5:4 Reserved RO

3 Far-end loopback 
mode

R/W 1 = Enabled. 0

2 Reserved RO

1 SGMII alignment 
error status

RO This is a self-clearing bit.
1 = Alignment error detected since last read.

0

0 Reserved RO

Table 31 • Extended PHY Control 1, Address 23 (0x17) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 42

4.2.20 Extended PHY Control Set 2
The second set of extended controls is located in register 24 in the main register space for the device. 
The following table shows the settings and readouts available.

Note: When bits 5:4 are set to Jumbo Packet mode, the default maximum packet values are based on 100 ppm 
driven reference clock to the device. Controlling the ppm offset between the MAC and the PHY as 
specified in the bit description results in a higher Jumbo packet length.

Table 32 • Extended PHY Control 2, Address 24 (0x18)

Bit Name Access Description Default
15:13 100BASE-TX edge 

rate control
R/W This is a sticky bit.

011 = +5 Edge rate (slowest).
010 = +4 Edge rate.
001 = +3 Edge rate.
000 = +2 Edge rate.
111 = +1 Edge rate.
110 = Default edge rate.
101 = –1 Edge rate.
100 = –2 Edge rate (fastest).

110

12 PICMG 2.16 reduced 
power mode

R/W This is a sticky bit.
1 = Enabled.

0

11:9 Reserved RO

8:7 SGMII input preamble R/W This is a sticky bit.
00 = No SGMII preamble required.
01 = One-byte SGMII preamble required.
10 = Two-byte SGMII preamble required.
11 = Reserved.

00

6 SGMII output 
preamble

R/W This is a sticky bit.
0 = No SGMII preamble.
1 = Two-byte SGMII preamble.

1

5:4 Jumbo packet mode R/W This is a sticky bit.
00 = Normal IEEE 1.5 kB packet length.
01 = 9 kB jumbo packet length (12 kB with 
60 ppm or better reference clock).
10 = 12 kB jumbo packet length (16 kB with 
70 ppm or better reference clock).
11 = Reserved.

00

3:1 100BASE-TX 
transmitter amplitude 
control

R/W 011 = +3 Amplitude setting (largest).
010 = +2 Amplitude setting.
001 = +1 Amplitude setting.
000 = Default amplitude.
111 = –1 Amplitude setting.
110 = –2 Amplitude setting.
101 = –3 Amplitude setting.
100 = –4 Amplitude setting (smallest).

000

0 1000BASE-T 
connector loopback

R/W  1 = Enabled. 0



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 43

4.2.21 Interrupt Mask
The bits in register 25 control the device interrupt mask. The following table shows the settings available.

Note: When bit 25.15 is set, the MDINT pin is enabled. When enabled, the state of this pin reflects the state of 
bit 26.15. Clearing this bit only inhibits the MDINT pin from being asserted. Also, before enabling this bit, 
read register 26 to clear any previously inactive interrupt pendings that will cause bit 25.15 to be set.

Table 33 • Interrupt Mask, Address 25 (0x19)

Bit Name Access Description Default
15 MDINT interrupt status enable R/W This is a sticky bit.

1 = Enabled.
0

14 Speed state change mask R/W This is a sticky bit.
1 = Enabled.

0

13 Link state change mask R/W This is a sticky bit.
1 = Enabled.

0

12 FDX state change mask R/W This is a sticky bit.
1 = Enabled.

0

11 Auto-negotiation error mask R/W This is a sticky bit.
1 = Enabled.

0

10 Auto-negotiation complete mask R/W This is a sticky bit.
1 = Enabled.

0

9 Inline powered device (PoE) detect mask R/W This is a sticky bit.
1 = Enabled.

0

8 Symbol error interrupt mask R/W This is a sticky bit.
1 = Enabled.

0

7 Fast link failure interrupt mask R/W This is a sticky bit.
1 = Enabled.

0

6 TX FIFO over/underflow interrupt mask R/W This is a sticky bit.
1 = Enabled.

0

5 RX FIFO over/underflow interrupt mask R/W This is a sticky bit.
1 = Enabled.

0

4 AMS media changed mask R/W This is a sticky bit.
1 = Enabled.

0

3 False-carrier interrupt mask R/W This is a sticky bit.
1 = Enabled.

0

2 Link speed downshift detect mask R/W This is a sticky bit.
1 = Enabled.

0

1 Master/Slave resolution error mask R/W This is a sticky bit.
1 = Enabled.

0

0 RX_ER interrupt mask R/W This is a sticky bit.
1 = Enabled.

0



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 44

4.2.22 Interrupt Status
The status of interrupts already written to the device are available for reading from register 26 in the main 
registers space. The following table shows the readouts you can expect. 

The following information applies to the interrupt status bits:

• All set bits in this register are cleared after being read (self-clearing). If bit 26.15 is set, the cause of 
the interrupt can be read by reading bits 26.14:0.

• For bits 26.14 and 26.12, bit 0.12 must be set for this interrupt to assert.
• For bit 26.7, register 19E bit 4 must be set for this interrupt to assert.
• For bit 26.2, bits 4.8:5 must be set for this interrupt to assert.
• For bit 26.0, this interrupt will not occur when RX_ER is used for carrier-extension decoding of a link-

partner’s data transmission.

Table 34 • Interrupt Status, Address 26 (0x1A)

Bit Name Access Description Default
15 Interrupt status RO This is a self-clearing bit.

1 = Interrupt pending.
0

14 Speed state change status RO This is a self-clearing bit.
1 = Interrupt pending.

0

13 Link state change status RO This is a self-clearing bit.
1 = Interrupt pending.

0

12 FDX state change status RO This is a self-clearing bit.
1 = Interrupt pending.

0

11 Auto-negotiation error status RO This is a self-clearing bit.
1 = Interrupt pending.

0

10 Auto-negotiation complete status RO This is a self-clearing bit.
1 = Interrupt pending.

0

9 Inline powered device detect status RO This is a self-clearing bit.
1 = Interrupt pending.

0

8 Symbol error status RO This is a self-clearing bit.
1 = Interrupt pending.

0

7 Fast link failure detect status RO This is a self-clearing bit.
1 = Interrupt pending.

0

6 TX FIFO over/underflow detect status RO This is a self-clearing bit.
1 = Interrupt pending.

0

5 RX FIFO over/underflow detect status RO This is a self-clearing bit.
1 = Interrupt pending.

0

4 AMS media changed status RO This is a self-clearing bit.
1 = Interrupt pending.

0

3 False-carrier interrupt status RO This is a self-clearing bit.
1 = Interrupt pending.

0

2 Link speed downshift detect status RO This is a self-clearing bit.
1 = Interrupt pending.

0

1 Master/Slave resolution error status RO This is a self-clearing bit.
1 = Interrupt pending.

0

0 RX_ER interrupt status RO This is a self-clearing bit.
1 = Interrupt pending.

0



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 45

4.2.23 MAC Interface Auto-Negotiation Control and Status
Device auto-negotiation for the MAC interface is controlled in register 27. The same register is used to 
check the status of those parameters. The following table shows the settings available. 

Table 35 • MAC Auto-Negotiation Control and Status, Address 27 (0x1B)

Bit Name Access Description Default
15 MAC or media 

interlock
R/W This is a sticky bit.

1 = MAC interface disabled when media link 
down.
0 = MAC interface not suppressed by media 
link status.

0

14 MAC or media 
restart 
auto-negotiation 
interlock 

R/W This is a sticky bit.
1 = MAC interface restarts its auto-negotiation 
if the media link changes.
0 = MAC interface does not automatically 
change if media link changes.

0

13 MAC interface 
auto-negotiation 
auto-sense

R/W This is a sticky bit.
1 = If MAC auto-negotiation is enabled, this 
allows the MAC interface to be able to link to 
MACs with auto-negotiation enabled and 
disabled.
0 = Normal MAC auto-negotiation behavior.

0

12 MAC interface 
auto-negotiation 
restart

R/W This is a self-clearing bit.
1 = Restart auto-negotiation.

0

11 MAC link partner 
restart request

RO This is a self-clearing bit.
Indicates a restart auto-negotiation request 
from a MAC link partner has occurred.

0

10 Reserved RO

9:8 Remote fault 
detected from MAC

RO Corresponds to the remote fault bits sent by 
the MAC during auto-negotiation.

00

7 Asymmetric pause 
advertised by the 
MAC

RO Corresponds to the asymmetric pause bit sent 
by the MAC during auto-negotiation.

0

6 Symmetric pause 
advertised by the 
MAC

RO Corresponds to the symmetric pause bit sent 
by the MAC during auto-negotiation.

0

5 Full-duplex 
advertised by the 
MAC

RO Corresponds to the full-duplex bit sent by the 
MAC during auto-negotiation.

0

4 Half-duplex 
advertised by the 
MAC

RO Corresponds to the half-duplex bit sent by the 
MAC during auto-negotiation.

0

3 MAC 
auto-negotiation 
capable

RO 1 = MAC is auto-negotiation capable. 0

2 MAC interface link 
status

RO 1 = The MAC interface is actively linked. 0



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 46

4.2.24 Device Auxiliary Control and Status
Register 28 provides control and status information for several device functions not controlled or 
monitored by other device registers. The following table shows the settings available and the readouts 
you can expect. 

1 MAC interface 
auto-negotiation 
complete

RO 1 = The MAC interface auto-negotiation is 
complete.

0

0 MAC interface 
signal detect

RO 1 = The MAC interface internal signal detect is 
asserted.

0

Table 36 • Auxiliary Control and Status, Address 28 (0x1C)

Bit Name Access Description Default
15 Auto-negotiation 

complete
RO Duplicate of bit 1.5. 0

14 Auto-negotiation 
disabled

RO Inverted duplicate of bit 0.12. 0

13 MDI/MDI-X crossover 
indication

RO 1 = MDI/MDI-X crossover performed 
internally.

0

12 CD pair swap RO 1 = CD pairs are swapped. 0

11 A polarity inversion RO 1 = Polarity swap on pair A. 0

10 B polarity inversion RO 1 = Polarity swap on pair B. 0

9 C polarity inversion RO 1 = Polarity swap on pair C. 0

8 D polarity inversion RO 1 = Polarity swap on pair D. 0

7 ActiPHY link status 
time-out control [1]

R/W This is a sticky bit.
Bits 7 and 2 are part of the ActiPHY Link 
Status time-out control.
Bit 7 is the MSB.
00: 2.3 seconds.
01: 3.3 seconds.
10: 4.3 seconds.
11: 5.3 seconds.

CMODE

6 ActiPHY mode enable R/W This is a sticky bit.
1 = Enabled.

0

5 FDX status RO 1 = Full-duplex.
0 = Half-duplex.

00

4:3 Speed status RO 00 = Speed is 10BASE-T.
01 = Speed is 100BASE-TX or 100BASE-FX.
10 = Speed is 1000BASE-T or 1000BASE-X.
11 = Reserved.

0

Table 35 • MAC Auto-Negotiation Control and Status, Address 27 (0x1B) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 47

4.2.25 LED Mode Select
The device LED outputs are controlled using the bits in register 29 of the main register space. The 
following table shows the information you need to access the functionality of each of the outputs. For 
information about the LED modes referenced in the table, see Table 4, page 18.In addition, if enabling 
the Extended LED mode bits in Register 19E bits 15 to 12, then also refer to Table 5, page 19. 

4.2.26 LED Behavior
The bits in register 30 control and enable you to read the status of the pulse or blink rate of the device 
LEDs. The following table shows the settings you can write to the register or read from the register. 

2 ActiPHY link status 
time-out control [0]

R/W This is a sticky bit.
Bits 7 and 2 are part of the ActiPHY Link 
Status time-out control.
Bit 7 is the MSB.
00: 2.3 seconds.
01: 3.3 seconds.
10: 4.3 seconds.
11: 5.3 seconds.

0

1:0 Media mode status RO 00 = No media selected.
01 = Copper media selected.
10 = SerDes media selected.
11 = Reserved.

00

Table 37 • LED Mode Select, Address 29 (0x1D)

Bit Name Access Description Default
15:12 LED3 mode select R/W This is a sticky bit.

Select from LED modes 0 through 15.
CMODE

11:8 LED2 mode select R/W This is a sticky bit.
Select from LED modes 0 through 15.

CMODE

7:4 LED1 mode select R/W This is a sticky bit.
Select from LED modes 0 through 15.

CMODE

3:0 LED0 mode select R/W This is a sticky bit.
Select from LED modes 0 through 15.

CMODE

Table 38 • LED Behavior, Address 30 (0x1E)

Bit Name Access Description Default
15 Copper and fiber LED 

combine disable
R/W This is a sticky bit.

0 = Combine enabled 
(Copper/Fiber on 
Link/LinkXXXX(1)/Activity LED).
1 = Disable combination 
(Link/LinkXXXX/Activity LED 
indicates copper only).

0

Table 36 • Auxiliary Control and Status, Address 28 (0x1C) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 48

14 Activity output select R/W This is a sticky bit.
1 = Activity LED becomes 
TX_Activity and fiber activity LED 
becomes RX_Activity.
0 = TX and RX activity both 
displayed on activity LEDs.

0

13 Reserved RO

12 LED pulsing enable R/W This is a sticky bit.
0 = Normal operation.
1 = LEDs pulse with a 5-kHz, 20% 
duty cycle when active.

0

11:10 LED blink/
pulse-stretch rate

R/W This is a sticky bit.
00 = 2.5-Hz blink rate / 400 ms 
pulse-stretch.
01 = 5-Hz blink rate / 200 ms pulse-
stretch.
10 = 10-Hz blink rate / 100 ms 
pulse-stretch.
11 = 20-Hz blink rate / 50 ms pulse-
stretch.
The blink rate selection for PHY0 
globally sets the rate used for all 
LED pins on all PHY ports.

CMODE

9 Reserved RO

8 LED3 pulse-stretch/
blink select

R/W This is a sticky bit.
1 = Pulse-stretch.
0 = Blink.

CMODE

7 LED2 pulse-stretch/
blink select

R/W This is a sticky bit.
1 = Pulse-stretch.
0 = Blink.

CMODE

6 LED1 pulse-stretch/
blink select

R/W This is a sticky bit.
1 = Pulse-stretch.
0 = Blink.

CMODE

5 LED0 pulse-stretch/
blink select

R/W This is a sticky bit.
1 = Pulse-stretch.
0 = Blink.

CMODE

4 Reserved RO

3 LED3 combine 
feature disable

R/W This is a sticky bit.
0 = Combine enabled (link/activity, 
duplex/collision).
1 = Disable combination (link only, 
duplex only).

CMODE

2 LED2 combine 
feature disable

R/W This is a sticky bit.
0 = Combine enabled (link/activity, 
duplex/collision).
1 = Disable combination (link only, 
duplex only).

CMODE

Table 38 • LED Behavior, Address 30 (0x1E) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 49

Note: Bits 29.11:10 are controlled only by port 0 and affect the behavior of all ports.

4.3 Extended Page Registers
To provide functionality beyond the IEEE802.3-specified 32 registers and main device registers, the 
VSC8662 device includes an extended set of registers that provide an additional 15 register spaces.

To access the extended page registers (16E through 30E), enable extended register access by writing 
0x0001 to register 31. For more information, see Table 40, page 50.

When extended page register access is enabled, reads and writes to registers 16 through 30 affect the 
extended registers 16E through 30E instead of those same registers in the IEEE-specified register 
space. Registers 0 through 15 are not affected by the state of the extended page register access.

Writing 0x0000 to register 31 restores the main register access.

The following table lists the addresses and register names in the extended register page space. These 
registers are accessible only when the device register 31 is set to 0x0001. 

1 LED1 combine 
feature disable

R/W This is a sticky bit.
0 = Combine enabled (link/activity, 
duplex/collision).
1 = Disable combination (link only, 
duplex only).

CMODE

0 LED0 combine 
feature disable

R/W This is a sticky bit.
0 = Combine enabled (link/activity, 
duplex/collision).
1 = Disable combination (link only, 
duplex only).

CMODE

1. Link10, Link100, Link1000, Link10/100, Link100/1000, Link1000BASE-X, or Link1000BASE-FX.

Table 39 • Extended Registers Page Space

Register Address Register Name
16E SerDes Media control

17E SerDes MAC/Media control

18E CRC good counter

19E SerDes loopback and SIGDET control

20E Extended PHY control 3 (ActiPHY)

21E Reserved

22E Reserved

23E Extended PHY control 4 (PoE and CRC error counter)

27E Reserved

28E SerDes MAC/media status

29E Ethernet packet generator (EPG) 1

30E EPG 2

Table 38 • LED Behavior, Address 30 (0x1E) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 50

4.3.1 Extended Page Access
The register at address 31 controls the access to both the extended and GPIO registers for the VSC8662 
device. Accessing the GPIO page register space is similar to accessing the extended page registers. The 
following table shows the settings available.

4.3.2 SerDes Media Control
Register 16E, which is accessible only when extended register access is enabled, controls the SerDes 
media interface. The following table shows the settings available. 

Table 40 • Extended Page Access, Address 31 (0x1F)

Bit Name Access Description Default
15:0 Extended/GPIO page 

register access
R/W 0x0000 = Register 16 through 30 accesses 

main register space
0x0001 = Register 16 through 30 accesses 
extended register space
0x0010 = Register 0 through 30 accesses 
GPIO register space

0x0000

Table 41 • SerDes Media Auto-Negotiation Control/Status, Address 16E (0x10)

Bit Name Access Description Default
15:14 Transmit remote fault R/W Remote fault indication sent to link partner 

(LP).
00

13:12 Link partner (LP) 
remote fault

RO Remote fault bits sent by LP during auto-
negotiation.

00

11 Parallel detect R/W 1 = Enables parallel detect of auto-
negotiation enabled and disabled devices.

0

10 SerDes media signal 
detect

RO Signal detect indication on media interface. 0

9 Allow 1000BASE-X 
link-up

R/W This is a sticky bit.
1 = Allows 1000BASE-X fiber media link-up 
capability.
0 = Suppress 1000BASE-X fiber media link-
up capability.

1

8 Allow 100BASE-FX 
link-up

R/W This is a sticky bit.
1 = Allows 100BASE-FX fiber media link-up 
capability.
0 = Suppress 100BASE-FX fiber media link-
up capability.

1

7 SerDes media LP 
restart request

RO This is a self-clearing bit.
1 = A restart auto-negotiation request from a 
SerDes media link partner has occurred.

0

6 Far end fault detected 
in 100BASE-FX

RO This is a self-clearing bit.
1 = Far end fault in 100BASE-FX detected.

0

5:0 Reserved RO



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 51

4.3.3 SerDes MAC/Media Control
Register 17E, which is accessible only when extended register access is enabled, controls the 
transmitter and receiver of the device SerDes MAC/Media. The following table shows the settings 
available. 

4.3.4 CRC Good Counter
Register 18E makes it possible to read the contents of the CRC good counter; the number of CRC 
routines that have executed successfully. The following table shows the readouts you can expect. 

Table 42 • SerDes MAC Control, Address 17E (0x11)

Bit Name Access Description Default
15:10 Reserved RO

9 SerDes media 
receiver equalization

R/W 1 = Receiver equalization enabled. 0

8 SerDes MAC receiver 
equalization

R/W 1 = Receiver equalization enabled. 0

7:5 SerDes media output 
swing control

R/W This is a sticky bit.
000 = 400 mV (peak-to-peak).
001 = 600 mV (peak-to-peak).
010 = 800 mV (peak-to-peak).
011 = 1000 mV (peak-to-peak).
100 = 1200 mV (peak-to-peak).
101 = 1400 mV (peak-to-peak).
110 and 111 = Reserved.

100

4:2 SerDes MAC output 
swing control

R/W This is a sticky bit.
000 = 400 mV (peak-to-peak).
001 = 600 mV (peak-to-peak).
010 = 800 mV (peak-to-peak).
011 = 1000 mV (peak-to-peak).
100 = 1200 mV (peak-to-peak).
101 = 1400 mV (peak-to-peak).
110 and 111 = Reserved.

100

1 SerDes MAC 
hysteresis

R/W 1 = Disabled. 0

0 SerDes media 
hysteresis

R/W 1 = Disabled. 0

Table 43 • CRC Good Counter, Address 18E (0x12)

Bit Name Access Description Default
15 Packet since last read RO This is a self-clearing bit.

1 = Packet received since last read.
0

14 Reserved RO

13:0 CRC good counter 
contents

RO This is a self-clearing bit.
Counter containing the number of packets 
with valid CRCs; this counter does not 
saturate and will roll over.

0x000



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 52

4.3.5 SerDes Loopback and SIGDET Control
Register 19E controls the SerDes loopback and SIGDET pin polarity, as well as the extended LED 
modes. The following table shows the settings available.

Table 44 • SerDes Loopback and SIGDET Control, Address 19E (0x13)

Bit Name Access Description Default
15 LED3 Extended Mode R/W 1 = See Extended LED Modes, page 19 for 

more information.
0

14 LED2 Extended Mode R/W 1 = See Extended LED Modes, page 19 for 
more information.

0

13 LED1 Extended Mode R/W 1 = See Extended LED Modes, page 19 for 
more information.

0

12 LED0 Extended Mode R/W 1 = See Extended LED Modes, page 19 for 
more information.

0

11 LED Reset Blink 
Suppress

R/W 1 = Blink LEDs after reset de-asserted.
0 = Suppress LED blink after reset de-
asserted.

Note: There is a design guideline 
related to this feature. For more 
information, see Enabling LED 
Blinking After Reset, page 94.

CMODE

10 SerDes media 
loopback enable

R/W 1 = Enables SerDes media loopback based 
on SerDes media loopback mode setting. If 
this bit is set, the loopback controls for far-end 
loopback (register 23.3) and isolate (register 
0.10) are disabled.
0 = Normal SerDes operation.

0

9:8 SerDes media 
loopback mode

R/W 00 = Pad loopback.
01 = SerDes serial loopback.
10 = SerDes parallel loopback.
11 = Normal data operation, but with 
recovered clock as SerDes transmit clock.

00

7 SerDes MAC 
loopback enable

R/W 1 = Enables SerDes MAC loopback based on 
the SerDes MAC loopback mode setting. If 
this bit is set, the loopback controls for far-end 
loopback (register 23.3) and isolate (Register 
0.10) are disabled.
0 = Normal SerDes operation.

0

6:5 SerDes MAC 
loopback mode

R/W 00 = Pad loopback.
01 = SerDes serial loopback.
10 = SerDes parallel loopback.
11 = Normal data operation, but with 
recovered clock as SerDes transmit clock.

00

4 Fast link failure 
indication

R/W 1 = Enabled.
0 = Disabled. GPIO9 pin becomes general 
purpose I/O.

0

3:2 Force MDI crossover R/W 00 = Normal MDI/MDI-X operation.
01 = Reserved.
10 = Copper media forced to MDI.
11 = Copper media forced MDI-X.

00



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 53

4.3.6 ActiPHY Control
Register 20E controls the device ActiPHY sleep timer, its wake-up timer, the frequency of the CLKOUT 
signal, and its link speed downshifting feature. The following table shows the settings available. 

1 Reserved RO

0 SIGDET pin polarity R/W This is a sticky bit.
1 = Active low.
0 = Active high.

CMODE

Table 45 • Extended PHY Control 3, Address 20E (0x14)

Bit Name Access Description Default
15 Disable carrier 

extension
R/W 1 = Disable carrier extension in SGMII 

1000BASE-T copper links. Also, adjust 
SGMII MAC support from v1.7 (default) to 
v1.8.

0

14:13 ActiPHY sleep timer R/W This is a sticky bit.
00 = 1 second.
01 = 2 seconds.
10 = 3 seconds.
11 = 4 seconds.

01

12:11 ActiPHY wake-up timer R/W This is a sticky bit.
00 = 160 ms.
01 = 400 ms.
10 = 800 ms.
11 = 2 seconds.

11

10 Reserved RO

9 PHY address reversal R/W 1 = Enabled. CMODE

8 CLKOUT frequency R/W This is a sticky bit.
1 = 156.25 MHz.
0 = 125 MHz.

CMODE

7:6 Media mode status RO 00 = No media selected. 
01 = Copper media selected. 
10 = SerDes media selected. 
11 = Reserved.

00

5 Enable 10BASE-T no 
preamble mode

R/W This is a sticky bit.
1 = 10BASE-T will assert RX_DV indication 
when data is presented to the receiver even 
without a preamble preceding it.

0

4 Enable link speed auto-
downshift feature

R/W This is a sticky bit.
1 = Enable auto link speed downshift from 
1000BASE-T.

CMODE

Table 44 • SerDes Loopback and SIGDET Control, Address 19E (0x13) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 54

Note: Bit 8 is valid only on PHY_0.

4.3.7 PoE and Miscellaneous Functionality
The register at address 23E controls various aspects of inline powering and the CRC error counter in the 
VSC8662. 

Note: Bits 9:8 are only valid if bit 10 is set.

4.3.8 SerDes MAC/Media Status
Register 28E in the extended register space provides access to the status of the SerDes MAC/Media. 
The following table shows the status available. 

3:2 Link speed 
auto-downshift control

R/W This is a sticky bit.
00 = Downshift after 2 failed 1000BASE-T 
auto-negotiation attempts.
01 = Downshift after 3 failed 1000BASE-T 
auto-negotiation attempts.
10 = Downshift after 4 failed 1000BASE-T 
auto-negotiation attempts.
11 = Downshift after 5 failed 1000BASE-T 
auto-negotiation attempts.

01

1 Link speed 
auto-downshift status

RO 0 = No downshift.
1 = Downshift is required or has occurred.

0

0 Reserved RO

Table 46 • Extended PHY Control 4, Address 23E (0x17)

Bit Name Access Description Default
15:11 PHY address RO PHY address; latched on reset. CMODE

10 Inline powered device 
detection

R/W This is a sticky bit.
1 = Enabled.

0

9:8 Inline powered device 
detection status

RO 00 = Searching for devices.
01 = Device found; requires inline power.
10 = Device found; does not require inline 
power.
11 = Reserved.

00

7:0 CRC error counter RO This is a self-clearing bit.
CRC error counter for the Ethernet packet 
generator. The value saturates at 0xFF and 
subsequently clears when read and restarts 
count.

0x00

Table 47 • SerDes MAC Status, Address 28E (0x1C)

Bit Name Access Description Default
15:12 Reserved RO 0000

11 MAC sync status fail RO This is a self-clearing bit.
1 = MAC Clause 36 synchronization state 
machine enters the LOSS_OF_SYNC state.

0

Table 45 • Extended PHY Control 3, Address 20E (0x14) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 55

4.3.9 Ethernet Packet Generator Control 1
The EPG control register provides access to and control of various aspects of the EPG testing feature. 
There are two, separate EPG control registers. The following table shows the setting available in the first 
register. 

10 MAC cgbad RO This is a self-clearing bit.
1 = Clause 36 cgbad variable is true.

0

9 MAC phase lock loss RO This is a self-clearing bit.
1 = A comma re-alignment occurred.

0

8 MAC RxPLL lock loss RO This is a self-clearing bit.
1 = RxPLL loss of lock occurred.

0

7:4 Reserved RO

3 SerDes media sync 
status fail

RO This is a self-clearing bit.
1 = SerDes Media Clause 36 synchronization 
state machine enters the LOSS_OF_SYNC 
state.

0

2 SerDes media cgbad RO This is a self-clearing bit.
1 = Clause 36 cgbad variable is true.

0

1 SerDes media phase 
lock loss

RO This is a self-clearing bit.
1 = A comma re-alignment occurred.

0

0 SerDes media RxPLL 
lock loss

RO This is a self-clearing bit.
1 = RxPLL loss of lock occurred.

0

Table 48 • EPG Control Register 1, Address 29E (0x1D)

Bit Name Access Description Default
15 EPG enable R/W 1 = Enable EPG 0

14 EPG run or stop R/W 1 = Run EPG 0

13 Transmission 
duration

R/W 1 = Continuous (sends in 10,000-packet 
increments)
0 = Send 30,000,000 packets and stop

0

12:11 Packet length R/W 00 = 125 bytes
01 = 64 bytes
10 = 1518 bytes
11 = 10,000 bytes (Jumbo packet)

0

10 Inter-packet gap R/W 1 = 8,192 ns
0 = 96 ns

0

9:6 Destination address R/W Lowest nibble of the 6-byte destination 
address

0001

5:2 Source address R/W Lowest nibble of the 6-byte destination 
address

0000

1 Payload type R/W 1 = Randomly generated payload pattern
0 = Fixed based on payload pattern 

0

0 Bad frame check 
sequence (FCS) 
generation

R/W 1 = Generate packets with bad FCS
0 = Generate packets with good FCS

0

Table 47 • SerDes MAC Status, Address 28E (0x1C) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 56

The following information applies to the EPG control number 1:

• Do not run the EPG when the VSC8662 device is connected to a live network.
• Bit 29E.13 (Continuous EPG mode control): When enabled, this mode causes the device to send 

continuous packets. When disabled, the device continues to send packets only until it reaches the 
next 10,000-packet increment mark. It then ceases to send packets.

• The six-byte destination address in bits 9:6 is assigned one of 16 addresses in the range of 0xFF FF 
FF FF FF F0 through 0xFF FF FF FF FF FF.

• The six-byte source address in bits 5:2 is assigned one of 16 addresses in the range of 0xFF FF FF 
FF FF F0 through 0xFF FF FF FF FF FF.

• If any of bits 13:0 are changed while the EPG is running (bit 14 is set to 1), bit 14 must be cleared 
and then set back to 1 for the change to take effect and to restart the EPG.

4.3.10 Ethernet Packet Generator Control 2
The register at address 30E consists of the second of bits that provide access to and control over various 
aspects of the EPG testing feature. For information about the first set of EPG control bits, see Table 48, 
page 55. The following table shows the settings available. 

Note: If any of bits 15:0 in this register are changed while the EPG is running (bit 14 of register 29E is set to 1), 
that bit (29E.14) must first be cleared and then set back to 1 for the change to take effect and to restart 
the EPG.

4.4 General-Purpose I/O Registers
Accessing the GPIO page register space is similar to accessing the extended page registers. Set register 
31 to 0x0010. This sets all 32 registers to the GPIO page register space.

To restore main register page access, write 0x0000 to register 31.

The following table lists the addresses and register names in the GPIO register page space. These 
registers are accessible only when the device register 31 is set to 0x0010. 

Table 49 • EPG Control Register 2, Address 30E (0x1E)

Bit Name Access Description Default
15:0 EPG packet payload R/W Data pattern repeated in the payload of 

packets generated by the EPG
0x00

Table 50 • General-Purpose Registers Page Space

Register Address Register Name
0G through 12G Reserved

13G SIGDET vs. GPIO control

14G Reserved

15G GPIO input

16G GPIO output

17G GPIO output enable

18G Reserved

19G Fast link fail control

20G I2C mux control 1

21G I2C mux control 2

22G I2C mux data read/write

23G Recovered clock 1

24G Recovered clock 2



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 57

4.4.1 Reserved GPIO Address Space
The bits in registers 0G to 12G, and 14G of the GPIO register page space are reserved.

4.4.2 SIGDET vs. GPIO Control 
The SIGDET control register configures GPIO pins 3:0 to be either SIGDET pins for each port or to be 
GPIO pins. The following table shows the values that can be written. 

4.4.3 GPIO Input 
The input register contains information about the input to the device GPIO pins. Read from this register to 
access the data on the device GPIO pins. The following table shows the readout you can expect. 

4.4.4 GPIO Output 
The output register allows you to access and control the output from the device GPIO pins. The following 
table shows the values you can write. 

25G LED port swapping

26G through 30G Reserved

Table 51 • SIGDET vs. GPIO Control, Address 13G (0x0D)

Bit Name Access Description Default
15:8 Reserved RO

7:4 Reserved R/W

3:2 SIGDET1 control R/W 00 = Normal SIGDET operation
01, 10 = Reserved
11 = Controlled by MII registers 15G to 17G

00

1:0 SIGDET0 control R/W 00 = Normal SIGDET operation
01, 10 = Reserved
11 = Controlled by MII registers 15G to 17G

00

Table 52 • GPIO Input, Address 15G (0x0F)

Bit Name Access Description Default
15:0 GPIO [15:0] input RO Data read from the GPIO pins 0x00

Table 53 • GPIO Output, Address 16G (0x10)

Bit Name Access Description Default
15:0 GPIO [15:0] output R/W Data written to the GPIO pins 0x00

Table 50 • General-Purpose Registers Page Space (continued)

Register Address Register Name



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 58

4.4.5 GPIO Pin Configuration
Register 17G in the GPIO register space controls whether a particular GPIO pin functions as an input or 
an output. The following table shows the settings available. 

4.4.6 Fast Link Fail Control
Register 19G in the GPIO register space controls the output of the fast link failure. The following table 
shows the settings available for the GPIO9 pin when enabled by register 19E, bit 4. 

4.4.7 Two-Wire Serial Mux Control 1
The following table shows the settings available to control the integrated two-wire serial mux. 

4.4.8 Two-Wire Serial Mux Control 2
Register 21G is used to control the two-wire serial mux for status and control of two-wire serial slave 
devices. 

Table 54 • GPIO Input/Output Configuration, Address 17G (0x11)

Bit Name Access Description Default
15:0 GPIO [15:0] input or 

output enable
R/W 1 = Pin is configured as an output.

0 = Pin is configured as an input.
0x00

Table 55 • GPIO Input/Output Configuration, Address 19G (0x13)

Bit Name Access Description Default
15:2 Reserved RO

0 Fast link failure port 
setting

R/W 0 = PHY0
1 = PHY1

00

Table 56 • Two-Wire Serial Mux Control 1, Address 20G (0x14)

Bit Name Access Description Default
15:9 I2C device address R/W Top 7 bits of the 8-bit address sent out on the 

two wire serial stream. The bottom bit is the 
read/write signal, which is controlled by 
register 21G, bit 8. SFPs use 0xA0.

0xA0

8:6 Reserved RO

5:4 I2C SCL clock 
frequency

R/W 00 = 50 kHz.
01 = 100 kHz.
10 = 400 kHz.
11 = 2 MHz.

01

3:2 Reserved R/W

1 I2C mux port 1 
enable

R/W 1 = Enabled.
0 = I2C disabled. Becomes GPIO pin.

0

0 I2C mux port 0 
enable

R/W 1 = Enabled.
0 = I2C disabled. Becomes GPIO pin.

0

Table 57 • Two-Wire Serial Mux Interface Status and Control, Address 21G (0x15)

Bit Name Access Description Default
15 I2C mux ready RO 1 = I2C mux is ready for read or write. 1



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 59

4.4.9 Two-Wire Serial Mux Data Read/Write
Register 22G in the extended register space enables access to the two-wire serial mux.  

4.4.10 Recovered Clock 1
The following table shows the settings available to control the RCVRD_CLK1 pin. 

14:12 Reserved RO

11 Reserved R/W

10 PHY port Address R/W Specific VSC8662 PHY port being 
addressed.

0

9 Enable I2C mux 
access

R/W This is a self-clearing bit.
1 = Execute read or write through the 
I2C mux based on the settings of 
register bit 21G.8.

0

8 I2C mux read or write R/W 1 = Read from I2C mux.
0 = Write to I2C mux.

1

7:0 I2C mux address R/W Sets the address of the I2C mux used to 
direct read or write operations.

0x00

Table 58 • Two-Wire Serial Mux Data Read/Write, Address 22G (0x16)

Bit Name Access Description Default
15:8 I2C mux read data RO 8-bit data read from I2C mux; requires 

setting both register 21G.9 and 21G.8 to 
1.

0x00

7:0 I2C mux write data R/W 8-bit data to be written to I2C mux. 0x00

Table 59 • Recovered Clock 1, Address 23G (0x17)

Bit Name Access Description Default
15 RCVRD_CLK1 enable R/W 1 = Enabled

0 = Disabled

Note: There is a design guideline 
related to this feature. For 
more information, see 
Disabling Recovered Clock 
Output, page 98.

0

14 Reserved RO

13 Reserved R/W

12 PHY clockout select R/W 0 = PHY0
1 = PHY1

00

11:9 Reserved RO

8 Clock frequency R/W 0 = 25 MHz
1 = 125 MHz

0

7:6 Reserved RO

Table 57 • Two-Wire Serial Mux Interface Status and Control, Address 21G (0x15) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 60

4.4.11 Recovered Clock 2
The following table shows the settings available to control the RCVRD_CLK2 pin. 

The following table shows the clock squelch modes that can be programmed into the RCVRD_CLK1 and 
RCVRD_CLK2 pins.  

5:4 Clock squelch R/W See Table 61, page 60 00

3:2 Reserved RO

1:0 Clock select R/W 00 = SerDes media
01 = Copper media
10 = Transmitter TCLK output
11 = Local XTAL1/REFCLK input

00

Table 60 • Recovered Clock 2, Address 24G (0x18)

Bit Name Access Description Default
15 RCVRD_CLK2 enable R/W 1 = Enabled

0 = Disabled
Note: There is a design guideline 

related to this feature. For 
more information, see 
Disabling Recovered Clock 
Output, page 98.

0

14 Reserved RO

13 Reserved R/W

12 PHY clockout select R/W 0 = PHY0
1 = PHY1

0

11:9 Reserved RO

8 Clock frequency R/W 0 = 25 MHz
1 = 125 MHz

0

7:6 Reserved RO

5:4 Clock squelch R/W See Table 61, page 60 00

3:2 Reserved RO

1:0 Clock select R/W 00 = SerDes media
01 = Copper media
10 = Reserved
11 = Local XTAL1/REFCLK input

00

Table 61 • Available Clock Squelch Settings

Bit 
Setting Clock Squelch Setting
00 Squelch recovered clock pin to low when:

• No link is detected (the link status register 1, bit 2 = 0).
• A fast link failure is detected (GPIO9 pin is asserted high).
• Active link is in 10BASE-T or 1000BASE-T master mode (unreliable recovered clock).

Table 59 • Recovered Clock 1, Address 23G (0x17) (continued)

Bit Name Access Description Default



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 61

4.4.12 LED Port Swapping
The following table shows the settings to swap the PHY port LEDs. 

4.5 CMODE
The information in this section provides a detailed description of the methods you can use to configure 
the VSC8662 device using its CMODE pins. It includes descriptions of the registers that work together 
with the CMODE pins to control the device function.

There are eight configuration mode (CMODE) pins on the VSC8662 device. For more information about 
the CMODE pin locations, see Miscellaneous Pins, page 80. Each of the CMODE pins maps to four 
configuration bits, which means that each pin controls 16 possible settings for the device. 

4.5.1 CMODE Pins and Related Functions
The following table lists the pin numbers and device functionality that are controlled by each 
configuration bit. 

01 Squelch recovered clock pin to low when:
• No link is detected (the link status register 1, bit 2 = 0).
• A fast link failure is detected (GPIO9 pin is asserted high).

10 Squelch recovered clock pin to low when:
No link is detected (the link status register 1, bit 2 = 0).

11 Squelch disabled. 
Note: Random clocks may appear on the clock out pin during auto-negotiation 

and when the link is not active. As a result, the clock might transition to the 
REFCLK input instead of the recovered clock.

Table 62 • LED Port Swapping, Address 25G (0x19)

Bit Name Access Description Default
15:2 Reserved RO

1 Reserved R/W

0 LED port swapping R/W See Table 7, page 21 0

Table 63 • CMODE Configuration Pins and Device Functions

CMODE Pin Bit 3 (MSB) Control Bit 2 Controls Bit 1 Controls Bit 0 (LSB) Controls
7 Reserved

Always set to logic 0
Link speed downshift Speed and duplex [1] Speed and duplex [0]

6 MAC auto-negotiation ActiPHY Advertise asymmetric 
pause

Advertise symmetric 
pause

5 Media interface [2] Reserved
Always set to logic 0

CLKOUT speed 125 
MHz or 156.25 MHz 
selection

CLKOUT enable

4 Media interface [1] SIGDET polarity PHY address reversal LED fiber/copper 
combine

3 Media interface [0] LED3 combine or 
separate

LED3 [1] LED3 [0]

Table 61 • Available Clock Squelch Settings (continued)

Bit 
Setting Clock Squelch Setting



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 62

4.5.2 Functions and Related CMODE Pins 
The following table lists the pin and bit settings according to the device function and CMODE pin used to 
configure them. 

2 PHY address [4] LED2 combine or 
separate

LED2 [1] LED2 [0]

1 PHY address [3] LED1 combine or 
separate

LED1 [1] LED1 [0]

0 PHY address [2] LED0 combine or 
separate

LED0 [1] LED0 [0]

Table 64 • Device Functions and Associated CMODE Pins

Function
Sets MII 
Register

CMODE 
Pin Bit Description

Link speed 
downshift

Register 20E, 
bit 4

7 2 0 = Link only according to the auto-negotiation resolution.
1 = Enable link speed downshift feature.

Speed and duplex Register 4, 
bits 8:5 and 
register 9, 
bits 9:8

7 1 and 0 00 = 10/100/1000BASE-T FDX/HDX. 1000BASE-
X/100BASE-FX FDX/HDX.
01 = 10/100/1000BASE-T FDX; 10/100BASE-T HDX. 
1000BASE-X FDX; 100BASE-FX HDX/FDX.
10 = 1000BASE-T FDX only.
11 = 10/100BASE-T FDX/HDX.

MAC 
auto-negotiation

Register 23, 
bit 13

6 3 0 = Disabled.
1 = Enabled.

ActiPHY Register 28, 
bit 6

6 2 0 = Disabled.
1 = Enabled.

Advertise 
asymmetric pause

Register 4, 
bit 11

6 1 0 = Not advertised.
1 = Advertised.

Advertise symmetric 
pause

Register 4, 
bit 10

6 0 0 = Not advertised.
1 = Advertised.

Media interface [2:0] Register 23, 
bits 10:8

5, 4, 3 3 000 = Cat5 copper only.
001 = SerDes Fiber/SFP Pass-Through mode only. No 
auto-negotiation performed in the PHY.
010 = 1000BASE-X Fiber/SFP mode only with auto-
negotiation performed by the PHY.
011 = 100BASE-X Fiber/SFP mode on the fiber media pins 
only.
101 = Auto-media sense with Cat5 media or SerDes 
Fiber/SFP Pass-Through mode.
110 = Auto-media sense with Cat5 media or 1000BASE-X 
Fiber/SFP mode with auto-negotiation performed by PHY.
111 = Auto-media sense with Cat5 media or 100BASE-FX 
Fiber/SFP mode.
100 = Reserved.

CLKOUT speed Register 20E, 
bit 8

5 1 0 = 125 MHz
1 = 156.25 MHz

CLKOUT enable Register 18, 
bit 0

5 0 0 = Disabled.
1 = Enabled.

Table 63 • CMODE Configuration Pins and Device Functions (continued)

CMODE Pin Bit 3 (MSB) Control Bit 2 Controls Bit 1 Controls Bit 0 (LSB) Controls



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 63

Note: The MAC auto-negotiation, LED_0, LED_1, LED_2, and LED_3 settings available using the CMODE 
pins and configuration bits is limited. For full functionality, use the registers. For more information about 
using the registers for these and other functions, see Registers, page 28.

SIGDET polarity Register 19E, 
bit 0

4 2 0 = Active high.
1 = Active low.

Address reversal 4 1 0 = Normal functioning.
PHY address 0:1 = Port 0:1.
1 = Reversed functioning.
PHY address 1:0 = Port 0:1.

LED fiber/copper 
combine 

Register 30, 
bit 15

4 0 0 = Combine enabled (Copper/Fiber on 
Link/LinkXXXX(1)/Activity LED).
1 = Disable combination (Link/LinkXXXX/Activity LED 
indicates copper only).

LED_3, LED_2, 
LED_1, and LED_0 
combine or separate

Register 30, 
bits 3:0

3, 2, 1, 
and 0

2 0 = Link, Link10, Link100, Link1000, Link10/100, 
Link10/1000, Link100/1000.
LEDs blink or flash when activity is present.
Also, a duplex LED blinks or flashes when collision is 
present.
1 = Link, Link10, Link100, Link1000, Link10/100, 
Link10/1000, Link100/1000.
LEDs indicate status only.
Also, a duplex LED indicates a duplex status only.

PHY address [4:2] 2, 1, 0 3 Sets the three MSBs of the PHY address.

LED_3 indication 
function

Register 29, 
bits 15:12

3 1 and 0 00 = Duplex or collision.
01 = Link100 or activity.
10 = Activity.
11 = Fiber_Link/Fiber_Activity.

LED_2 indication 
function

Register 29, 
bits 11:8

2 1 and 0 00 = Link or activity.
01 = Duplex or collision.
10 = Fiber_Activity.
11 = Link10 or activity.

LED_1 indication 
function

Register 29, 
bits 7:4

1 1 and 0 00 = Link100 or activity.
01 = Link100/1000 or activity.
10 = Link 10/100 or activity.
11 = Fiber_Link/Fiber_Activity.

LED_0 indication 
function

Register 29, 
bits 3:0

0 1 and 0 00 = Link1000 or activity.
01 = Link100/1000 or activity.
10 = Activity.
11 = Link or activity.

1. Link10, Link100, Link1000, Link10/100, Link100/1000, Link1000BASE-X, or Link1000BASE-FX.

Table 64 • Device Functions and Associated CMODE Pins (continued)

Function
Sets MII 
Register

CMODE 
Pin Bit Description



Configuration

VMDS-10312 VSC8662 Datasheet Revision 4.3 64

4.5.3 CMODE Resistor Values
To affect an aspect of the VSC8662 device configuration, find the parameter in Table 63, page 61 or in 
Table 64, page 62, and connect the associated pin to the resistor specified in the following table. This 
sets the bits as shown. 

Using resistors with the CMODE pins can be optional in designs that access the device’s MDC/MDIO 
pins. In designs that do this, all configurations otherwise affected on the device by using the CMODE 
pins can be changed using the regular device register settings, and all the CMODE pins can be pulled to 
VSS (ground). However, in this case, the PHYADDR [4:2] and the PHYADD_REVERSAL settings still 
require CMODE configuration. This configuration can be set by connecting these pins to either the 
VDD33 or VSS pins.

Table 65 • CMODE Resistor Values and Resultant Bit Settings

With CMODE 
Pin Tied To

With 1% 
Resistor Value

Set
Bit 3 (MSB) to:

Set
Bit 2 to:

Set
Bit 1 to:

Set
Bit 0 (LSB) to:

VSS 0 0 0 0 0

VSS 2.26 kΩ 0 0 0 1

VSS 4.02 kΩ 0 0 1 0

VSS 5.90 kΩ 0 0 1 1

VSS 8.25 kΩ 0 1 0 0

VSS 12.1 kΩ 0 1 0 1

VSS 16.9 kΩ 0 1 1 0

VSS 22.6 kΩ 0 1 1 1

VDD33 0 1 0 0 0

VDD33 2.26 kΩ 1 0 0 1

VDD33 4.02 kΩ 1 0 1 0

VDD33 5.90 kΩ 1 0 1 1

VDD33 8.25 kΩ 1 1 0 0

VDD33 12.1 kΩ 1 1 0 1

VDD33 16.9 kΩ 1 1 1 0

VDD33 22.6 kΩ 1 1 1 1



Electrical Specifications

VMDS-10312 VSC8662 Datasheet Revision 4.3 65

5 Electrical Specifications

This section provides the DC characteristics, AC characteristics, recommended operating conditions, 
and stress ratings for the VSC8662 device. It includes information on the various timing functions of the 
device.

5.1 DC Characteristics
In addition to any parameter-specific conditions, the specifications listed in the following tables may be 
considered valid only in the environment characterized by the specifications listed as recommended 
operating conditions for the VSC8662 device. For more information about the recommended operating 
conditions, see Operating Conditions, page 75.

5.1.1 VDDIO at 3.3 V
In addition to any parameter-specific conditions, the specifications listed in the following table may be 
considered valid only when:

• VDDIO is 3.3 V
• VDD33 is 3.3 V
• VDD12 is 1.2 V
• VDD12A is 1.2 V 

5.1.2 VDDIO at 2.5 V
In addition to any parameter-specific conditions, the specifications listed in the following table may be 
considered valid only when:

• VDDIO is 2.5 V
• VDD33 is 3.3 V
• VDD12 is 1.2 V
• VDD12A is 1.2 V 

Table 66 • DC Characteristics for Pins Referenced to VDDIO at 3.3 V

Parameter Symbol Minimum Maximum Unit Condition
Output high voltage VOH 2.4 3.6 V IOH = –4 mA

Output low voltage VOL 0 0.5 V IOL = 4 mA

Input high voltage VIH 2.1 3.6 V

Input low voltage VIL –0.3 0.9 V

Input leakage current IILEAK –42 42 µA Internal resistor included

Output leakage 
current

IOLEAK –42 42 µA Internal resistor included

Output low current 
drive strength

IOL 8 mA

Output high current 
drive strength

IOH –8 mA

Table 67 • DC Characteristics for Pins Referenced to VDDIO at 2.5 V

Parameter Symbol Minimum Maximum Unit Condition
Output high voltage VOH 2.0 2.8 V IOH = –1.0 mA

Output low voltage VOL –0.3 0.4 V IOL = 1.0 mA



Electrical Specifications

VMDS-10312 VSC8662 Datasheet Revision 4.3 66

5.1.3 VDDIO at 1.8 V
In addition to any parameter-specific conditions, the specifications listed in the following table may be 
considered valid only when:

• VDDIO is 1.8 V
• VDD33 is 3.3 V
• VDD12 is 1.2 V
• VDD12A is 1.2 V 

5.1.4 VDD33 at 3.3 V
In addition to any parameter-specific conditions, the specifications listed in the following table may be 
considered valid only when:

• VDDIO is 3.3 V
• VDD33 is 3.3 V
• VDD12 is 1.2 V
• VDD12A is 1.2 V 

Input high voltage VIH 1.7 3.0 V

Input low voltage VIL –0.3 0.7 V

Input leakage current IILEAK –32 32 µA Internal resistor included

Output leakage current IOLEAK –32 32 µA Internal resistor included

Output low current 
drive strength

IOL 6 mA

Output high current 
drive strength

IOH –6 mA

Table 68 • DC Characteristics for Pins Referenced to VDDIO at 1.8 V

Parameter Symbol Minimum Maximum Unit Condition
Output high voltage VOH 1.4 2.1 V IOH = –0.5 mA

Output low voltage VOL 0.3 V IOL = 0.5 mA

Input high voltage VIH 1.2 2.1 V

Input low voltage VIL 0.6 V

Input leakage current IILEAK –23 23 µA Internal resistor included

Output leakage 
current

IOLEAK –23 23 µA Internal resistor included

Output low current 
drive strength

IOL 4.0 mA

Output high current 
drive strength

IOH –4.0 mA

Table 69 • DC Characteristics for Pins Referenced to VDD33 at 3.30 V

Parameter Symbol Minimum Maximum Unit Condition
Output high voltage VOH 2.4 3.6 V IOH = –4 mA

Output low voltage VOL 0 0.5 V IOL = 4 mA

Table 67 • DC Characteristics for Pins Referenced to VDDIO at 2.5 V (continued)

Parameter Symbol Minimum Maximum Unit Condition



Electrical Specifications

VMDS-10312 VSC8662 Datasheet Revision 4.3 67

5.1.5 DC Characteristics for MAC and SerDes Media Outputs
For more information about the MAC output pins, see SerDes MAC Interface, page 82. For more 
information about the SerDes media output pins, see SerDes Media Interface, page 83. For more 
information about the AC characteristics, see AC Characteristics for MAC and SerDes Media Outputs, 
page 71. 

5.1.6 DC Characteristics for MAC and SerDes Media Inputs
For more information about the MAC input pins, see SerDes MAC Interface, page 82. For more 
information about the SerDes media input pins, see SerDes Media Interface, page 83. For more 
information about the AC characteristics, see AC Characteristics for MAC and SerDes Media Inputs, 
page 71.

Input high voltage VIH 2.1 3.6 V

Input low voltage VIL –0.3 0.9 V

Input leakage current IILEAK –42 42 µA Internal resistor included

Output leakage current IOLEAK –42 42 µA Internal resistor included

Output low current 
drive strength

IOL 8 mA

Output high current 
drive strength

IOH –8 mA

Table 70 • DC Characteristics for MAC_RDP/N_n and FIBR_DOP/N_n Pins  

Parameter Symbol Minimum Typical Maximum Unit Condition
Frequency lock time TLOCK 500 µs

Output differential 
voltage

VODIFF 700 1000 1200 mV Measured peak-to-
peak. Based on 
100 Ω differential 
load.

Output common-
mode voltage

VOCM 480 540 610 mV VDD12A = 1.20 V.

Output low current 
drive strength

IOL 8 mA

Output high current 
drive strength

IOH –8 mA

Output driver 
impedance per pin

ZO 50 Ω

Table 71 • DC Characteristics for MAC_TDP/N_n and FIBR_DIP/N_n Pins

Parameter Symbol Minimum Maximum Unit Condition
Input differential voltage VIDIFF 120 2400 mV Measured peak-to-peak. 

Based on 100 Ω 
differential load.

Input common mode 
voltage

VICM 0.4 1.3 V VDD12A = 1.20 V.

Table 69 • DC Characteristics for Pins Referenced to VDD33 at 3.30 V (continued)

Parameter Symbol Minimum Maximum Unit Condition



Electrical Specifications

VMDS-10312 VSC8662 Datasheet Revision 4.3 68

5.1.7 LED Pins
In addition to any parameter-specific conditions, the specifications listed in the following table may be 
considered valid only when:

• VDDIO is 3.3 V
• VDD33 is 3.3 V
• VDD12 is 1.2 V
• VDD12A is 1.2 V

5.1.8 JTAG Pins
In addition to any parameter-specific conditions, the specifications listed in the following table may be 
considered valid only when:

• VDDIO is 3.3 V
• VDD33 is 3.3 V
• VDD12 is 1.2 V
• VDD12A is 1.2 V

5.2 Current Consumption
There are three sets of current consumption values:

• Typical current consumption
• Current consumption in SerDes/SGMII to 1000BASE-X mode
• Current consumption in SerDes/SGMII to 100BASE-FX mode or SerDes pass-through mode

Table 72 • DC Characteristics for LED[3:0]_n Pins  

Parameter Symbol Minimum Maximum Unit Condition
Output high voltage VOH 2.4 3.6 V IOH = –4.0 mA

Output low voltage VOL 0 0.5 V IOL = 4.0 mA

Output leakage current IOLEAK –10 10 µA

Output low current drive strength IOL 8.0 mA

Output high current drive strength IOH –8.0 mA

Table 73 • DC Characteristics for JTAG Pins

Parameter Symbol Minimum Maximum Unit Condition
Output high voltage VOH 2.4 3.6 V IOH = –1.5 mA

Output low voltage VOL 0 0.5 V IOL = 1.5 mA

Input high voltage VIH 2.1 3.6 V

Input low voltage VIL –0.3 0.9 V

Input leakage current IILEAK –42 42 µA Internal resistor included

Output leakage current IOLEAK –42 42 µA Internal resistor included

Output low current drive 
strength

IOL 8 mA

Output high current 
drive strength

IOH –8 mA



Electrical Specifications

VMDS-10312 VSC8662 Datasheet Revision 4.3 69

The typical current consumption values are based on nominal voltages with all ports operating at 
1000BASE-T speeds with full-duplex enabled and a 64-bit random data pattern at 100% utilization.

If all ports are running in SerDes/SGMII to 1000BASE-X mode, the current consumption values are 
shown in the following table.

If all ports are running in SerDes/SGMII to 100BASE-FX mode or SerDes pass-through mode, the 
current consumption values are as shown in the following table.

Table 74 • Typical Current Consumption

Parameter Symbol Typical Maximum Unit
Worst-case power consumption PD 3.19 W

Current with VDDIO at 1.8 V IVDDIO 1 mA

Current with VDDIO at 2.5 V IVDDIO 1 mA

Current with VDDIO at 3.3 V IVDDIO 1 mA

Current with VDD33 at 3.3 V IVDD33 228 mA

Current with VDD12 at 1.2 V IVDD12 390 mA

Current with VDD12A at 1.2 V IVDD12A 224 mA

Table 75 • Current Consumption in SerDes/SGMII to 1000BASE-X Mode

Parameter Symbol Typical Maximum Unit
Worst-case power consumption(1)

1. Worst-case power only applies if the 1000BASE-X media operating mode is set by CMODE 
configuration. When any Cat5 media operating mode is selected using CMODE, the worst-case 
power consumption in the preceding table applies. For information, see Table 74, page 69.

PD 0.57 W

Current with VDDIO at 1.8 V IVDDIO 1 mA

Current with VDDIO at 2.5 V IVDDIO 1 mA

Current with VDDIO at 3.3 V IVDDIO 1 mA

Current with VDD33 at 3.3 V IVDD33 38 mA

Current with VDD12 at 1.2 V IVDD12 58 mA

Current with VDD12A at 1.2V IVDD12A 238 mA

Table 76 • Consumption in SerDes/SGMII to 100BASE-FX or SerDes Pass-Through Mode

Parameter Symbol Typical Maximum Unit
Worst-case power consumption(1)

1. Worst-case power only applies if the 100BASE-FX media operating mode is set by CMODE 
configuration. When any Cat5 media operating mode is selected using CMODE, the worst-case 
power consumption listed earlier in this section applies. For information, see Table 74, page 69.

PD 0.59 W

Current with VDDIO at 1.8 V IVDDIO 1 mA

Current with VDDIO at 2.5 V IVDDIO 1 mA

Current with VDDIO at 3.3 V IVDDIO 1 mA

Current with VDD33 IVDD33 34 mA

Current with VDD12 IVDD12 49 mA

Current with VDD12A IVDD12A 202 mA



Electrical Specifications

VMDS-10312 VSC8662 Datasheet Revision 4.3 70

5.3 AC Characteristics
The AC specifications are grouped according to specific device pins and associated timing 
characteristics.

5.3.1 Reference Clock Input
The following table shows the specifications for the reference clock input frequency including various 
frequencies, duty cycle, and accuracy.

If using the 25 MHz crystal clock input option, the additional specifications in the following table are 
required.

5.3.2 Clock Output
The specifications in the following table show the AC characteristics for the clock output of the VSC8662 
device.

Table 77 • AC Characteristics for REFCLK Input

Parameter Symbol Minimum Typical Maximum Unit Condition
Frequency with 25 MHz input fCLK25 25 MHz

Frequency with 125 MHz input fCLK125 125 MHz

Frequency accuracy fTOL 100 ppm

Duty cycle %DUTY 40 60 %

RMS jitter tolerance(1)

1. Sinusoidal jitter, with BER 10–12 divided by 14.1.

JTOL 145
42
42
55

ps
ps
ps
ps

1 kHz
10 kHz
200 kHz
10 MHz

Rise time with 25 MHz input 
(20% to 80%)

tR25 4 ns

Rise time with 125 MHz input 
(20% to 80%)

tR125 1 ns

Fall time with 25 MHz input 
(20% to 80%)

tR25 4 ns

Fall time with 125 MHz input 
(20% to 80%)

tF125 1 ns

Table 78 • AC Characteristics for REFCLK Input with 25 MHz Clock Input

Parameter Minimum Typical Maximum Unit
Crystal parallel load capacitance 18 20 pF

Crystal equivalent series resistance 10 30 Ω

Crystal accuracy 50 ppm

Table 79 • AC Characteristics for the CLKOUT Pin

Parameter Symbol Minimum Typical Maximum Unit Condition
CLKOUT frequency fCLK125

fCLK156.25
125.00
156.25

MHz 125 MHz output clock
156.25 MHz output clock



Electrical Specifications

VMDS-10312 VSC8662 Datasheet Revision 4.3 71

5.3.3 Recovered Clock Outputs
The specifications in the following table show the AC characteristics for the recovered clock outputs of 
the VSC8662 device.

5.3.4 AC Characteristics for MAC and SerDes Media Outputs
For more information about the MAC output pins, see SerDes MAC Interface, page 82. For more 
information about the SerDes media output pins, see SerDes Media Interface, page 83. For more 
information about the DC characteristics, see DC Characteristics for MAC and SerDes Media Outputs, 
page 67.

5.3.5 AC Characteristics for MAC and SerDes Media Inputs
For more information about the MAC input pins, see SerDes MAC Interface, page 82. For more 
information about the SerDes media input pins, see SerDes Media Interface, page 83. For more 

CLKOUT cycle time tCYC 8.0
6.4

ns 125 MHz output clock
156.25 MHz output clock

Frequency stability fSTABILITY 100 ppm

Duty cycle %DUTY 40 50 60 %

Clock rise and fall times 
(20% to 80%)

tR and tF 425 ps

Total jitter JCLK 100 150 ps Measured peak-to-peak 

Table 80 • AC Characteristics for the RCVRD_CLK Pins

Parameter Symbol Minimum Typical Maximum Unit Condition
RCVRD_CLK frequency fRCLK125 125.00

25.00
MHz 125 MHz output clock

25 MHz output clock

RCVRD_CLK cycle time tRCYC 8.0
40

ns 125 MHz output clock
25 MHz output clock

Frequency stability fSTABILITY 50 ppm

Duty cycle %DUTY 45 50 55 %

Clock rise and fall times 
(20% to 80%)

tR and tF 600 ps

Total jitter for 1000BASE-T JCLK 325 400 ps Measured peak-to-peak 

Total jitter for SerDes JCLK 200 250 ps Measured peak-to-peak 

Table 81 • AC Characteristics for MAC_RDP/N_n and FIBR_DOP/N_n Pins  

Parameter Symbol Typical Maximum Unit Condition
Output rise time and 
fall time (20% to 80%)

tr , tf 300 ps

Total output jitter TJ 185 260 ps Measured peak-to-peak. 
Uses K28.5 test pattern. Bit 
error rate (BER) = 10–12.

Table 79 • AC Characteristics for the CLKOUT Pin (continued)

Parameter Symbol Minimum Typical Maximum Unit Condition



Electrical Specifications

VMDS-10312 VSC8662 Datasheet Revision 4.3 72

information about the DC characteristics, see DC Characteristics for MAC and SerDes Media Inputs, 
page 67.

5.3.6 JTAG Interface
The following table lists the characteristics for the JTAG testing feature. The illustration provides a 
diagram of the timing.

Figure 21 • JTAG Interface Timing 

Table 82 • AC Characteristics for MAC_TDP/N_n and FIBR_DIP/N_n Pins

Parameter Symbol Minimum Maximum Unit Condition
Total receive jitter 
tolerance

JRXTotal 610 ps Measured peak-to-peak. 
1000BASE-X mode.

JRXTotal 6500 ps Measured peak-to-peak. 
100BASE-FX mode.

Table 83 • AC Characteristics for the JTAG Interface

Parameter Symbol Minimum Maximum Unit
TCK frequency fCLK 10 MHz

TCK cycle time tCYC 100 ns

TCK time high tWH 45 ns

TCK time low tWL 45 ns

Setup time to TCK rising tSU 10 ns

Hold time from TCK rising tH 10 ns

TCK to TDO valid tCO 15 ns

TCK

TDI
TMS

tSU tH

tCYC

tWH tWL

tCO

TDO



Electrical Specifications

VMDS-10312 VSC8662 Datasheet Revision 4.3 73

5.3.7 SMI Interface
Use the information in the following table when incorporating the VSC8662 device SMI interface into your 
own design. The illustration provides information about SMI interface timing.

Figure 22 • SMI Interface Timing

5.3.8 Device Reset
The following specifications apply to the device reset functionality. The illustration shows the reset timing.

Table 84 • AC Characteristics for the SMI Interface

Parameter Symbol Minimum Typical Maximum Unit Condition
MDC frequency(1)

1. For fCLK above 1 MHz, the minimum rise time and fall time is in relation to the frequency of the MDC clock period. For example, 
if fCLK is 2 MHz, the minimum clock rise time and fall time is 50 ns.

fCLK 2.5 12.5 MHz

MDC cycle time tCYC 80 400 ns

MDC time high tWH 20 50 ns

MDC time low tWL 20 50 ns

Setup to MDC rising tSU 10 ns

Hold from MDC 
rising

tH 10 ns

MDC rise time tR 100
tCYC × 10%(1)

ns For MDC = 0 – 1 MHz
For MDC = 1 MHz – fCLK(MAX)

MDC fall time tF 100
tCYC × 10%(1)

MDC to MDIO valid tCO 10 300 ns Time-dependant on the value of 
the external pull-up resistor on 
the MDIO pin

Table 85 • AC Characteristics for Device Reset

Parameter Symbol Minimum Maximum Unit Condition
NRESET assertion time tRESET 100 ns

Wait time between NRESET de-assert 
and access of the SMI interface

tWAIT 20 ms
ms

tSU

Data

MDC

tH

tWL tWH

tCO

Data

tCYC

MDIO
(write)

MDIO
(read)



Electrical Specifications

VMDS-10312 VSC8662 Datasheet Revision 4.3 74

Figure 23 • Reset Timing

5.3.9 Serial LEDs
The following table provides specifications for the device serial LEDs. The illustration shows the LED 
timing. For information about initial synchronization requirements, see Serial LED Mode, page 20

Soft reset (pin) assertion tSRESET_ASSERT 4 ms

Soft reset (pin) de-assertion tSRESET_DEASSERT 4 ms

Wait time between soft reset pin de-
assert and access of the SMI interface

tSWAIT 4
300

µs
µs

Registers 22.9 = 1
Registers 22.9 = 0

Soft reset MII register 0.15 assertion tSREG_RESET 100 ns

Wait time between Soft Reset (MII 
Register 0.15) de-assert and access to 
the SMI interface

tSREG_WAIT 4
300

µs
µs

Registers 22.9 = 1
Registers 22.9 = 0

Table 86 • AC Characteristics for Serial LEDs

Parameter Symbol Minimum Maximum Unit
LED_CLK cycle time tCYC 1 µs

Pause between LED bit sequences tPAUSE 25 ms

LED_CLK to LED_DATA tCO 1 ns

Table 85 • AC Characteristics for Device Reset (continued)

Parameter Symbol Minimum Maximum Unit Condition

NRESET
tRESET

REFCLK

tWAIT

MDIO

Soft Reset 
(MII Register 0.15)

tSREG_RESET

tSREG_WAIT

Undefined State

MDC

NSRESET
tSRESET_ASSERT

tSWAIT

tSRESET_DEASSERT



Electrical Specifications

VMDS-10312 VSC8662 Datasheet Revision 4.3 75

Figure 24 • Serial LED Timing

5.4 Operating Conditions
The following table shows the recommended operating conditions for the VSC8662 device. 

5.5 Stress Ratings
This section contains the stress ratings for the VSC8662 device.

Warning Stresses listed in the following table may be applied to devices one at a time without causing 
permanent damage. Functionality at or exceeding the values listed is not implied. Exposure to these 
values for extended periods may affect device reliability.

Table 87 • Recommended Operating Conditions

Parameter Symbol Minimum Typical Maximum Unit
Power supply voltage for VDDIO at 1.8 V VDDIO 1.70 1.80 1.90 V

Power supply voltage for VDDIO at 2.5 V VDDIO 2.37 2.50 2.63 V

Power supply voltage for VDDIO at 3.3 V VDDIO 3.13 3.30 3.47 V

Power supply voltage for VDD33 VDD33 3.13 3.30 3.47 V

Power supply voltage for VDD12 VDD12 1.14 1.20 1.26 V

Power supply voltage for VDD12A VDD12A 1.14 1.20 1.26 V

VSC8662 operating temperature(1)

1. Lower limit of specification is ambient temperature, and upper limit is case temperature.

T 0 90 °C

VSC8662-03 operating temperature(1) T –40 100 °C

Table 88 • Stress Ratings

Parameter Symbol Minimum Maximum Unit
DC input voltage on VDDIO supply pin VDDIO –0.5 4.0 V

DC input voltage on VDD33 supply pin VDD33 –0.5 4.0 V

DC input voltage on VDD12 supply pin VDD12 –0.5 1.4 V

DC input voltage on VDD12A supply pin VDD12A –0.5 1.4 V

DC input voltage on JTAG 5 V-tolerant pins VDD(5 V) –0.5 5.5 V

DC input voltage on any non-supply pin VDD(PIN) –0.5 VDD + 0.5 V

Storage temperature TS –65 150 oC

Electrostatic discharge voltage, charged device 
model

VESD_CDM –500 500 V

Electrostatic discharge voltage, human body model VESD_HBM See note(1) V

LED_CLK

LED_DATA Bit 1

tCO

tCYC tCYCtPAUSE

Bit 2 Bit 48 Bit 1



Electrical Specifications

VMDS-10312 VSC8662 Datasheet Revision 4.3 76

Warning This device can be damaged by electrostatic discharge (ESD) voltage. Vitesse recommends 
that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling 
and installation procedures may adversely affect reliability of the device.

1. This device has completed all required testing as specified in the JEDEC standard JESD22-A114, 
Electrostatic Discharge (ESD) Sensitivity Testing Human Body Model (HBM), and complies with a Class 2 
rating. The definition of Class 2 is any part that passes an ESD pulse of 2000 V, but fails an ESD pulse of 
4000 V.



Pin Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 77

6 Pin Descriptions

The VSC8662 device has 256 pins, which are described in this section.

The pin information is also provided as an attached Microsoft Excel file so that you can copy it 
electronically. In Acrobat, double-click the attachment icon.

6.1 Pin Diagram
The following illustration shows the pin diagram for the VSC8662 device. For clarity, the device is shown 
in two halves, the top left and top right. 

Figure 25 • Pin Diagram, Top Left

1 2 3 4 5 6 7 8
A NC RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED

B VSS RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED

C XTAL2 VDD33 VSS VDD33 VSS VDD33 VDD12A VDD12A

D XTAL1/REFCLK OSCEN REF_FILT REF_REXT VSS VSS VSS VSS

E PLLMODE TMS NTRST VDD33 VDD12 VSS VSS VSS

F TDO TDI TCK VSS VDD12 VSS VSS VSS

G LED0_0 LED1_0 LED2_0 LED3_0 VDD12 VSS VSS VSS

H LED0_1 LED1_1 LED2_1 LED3_1 VDD12 VSS VSS VSS

J RESERVED RESERVED RESERVED RESERVED VDD12 VSS VSS VSS

K RESERVED RESERVED RESERVED RESERVED VDD12 VSS VSS VSS

L RESERVED RESERVED NSRESET VSS VDD12 VSS VSS VSS

M RESERVED MDINT0 NRESET VDDIO VDD12 VSS VSS VSS

N RESERVED MDIO MDINT1 RESERVED VDD12 VSS VSS VSS

P RESERVED MDC VDDIO VSS VDD33 VDD12A VDD12A VDD12A

R VSS RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED

T NC RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED



Pin Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 78

Figure 26 • Pin Diagram, Top Right

6.2 Pin Identifications
This section contains the pin descriptions for the VSC8662 device. The following table provides notations 
for definitions of the various pin types.

Table 89 • Pin Type Symbols

Symbol Pin Type Description
I Input Input with no on-chip pull-up or pull-down resistor.

IPU Input with pull-up Input with on-chip pull-up resistor to VDDIO.

IPD Input with pull-down Input with on-chip pull-down resistor to VSS.

IDIFF Input differential Input differential signal pair

IPU/O Bidirectional with pull-
up

Input and output signal with on-chip pull-up resistor to 
VDDIO or VDD33.

O Output Output signal.

OPU Output with pull-up Output with on-chip pull-up resistor to VDDIO.

OD Open drain Open drain output.

OS Open source Open source output.

ODIFF Output differential Output differential signal pair.

9 10 11 12 13 14 15 16

RESERVED TXVPA_1 TXVPB_1 TXVPC_1 TXVPD_1 TXVPA_0 TXVPB_0 NC A

RESERVED TXVNA_1 TXVNB_1 TXVNC_1 TXVND_1 TXVNA_0 TXVNB_0 VSS B

VDD12A RESERVED VDD33 VSS VDD12A VDD33 TXVNC_0 TXVPC_0 C

VSS VSS VSS VSS RESERVED CMODE5 TXVND_0 TXVPD_0 D

VSS VSS VSS VDD12 RESERVED CMODE4 CMODE6 CMODE7 E

VSS VSS VSS VDD12 RESERVED CMODE2 CMODE3 RCVRD_CLK1 F

VSS VSS VSS VDD12 CMODE0 CMODE1 CLKOUT RCVRD_CLK2 G

VSS VSS VSS VDD12 VDD33 GPIO13 THERMDC THERMDA H

VSS VSS VSS VDD12 VSS GPIO12 GPIO14 GPIO15 J

VSS VSS VSS VDD12 GPIO8/I2C_SDA GPIO9/FastLinkFail GPIO10 GPIO11 K

VSS VSS VSS VDD12 GPIO4/I2C_SCL_0 GPIO5/I2C_SCL_1 GPIO6 GPIO7 L

VSS VSS VSS VDD12 VDD33 GPIO1/SIGDET1 GPIO2 GPIO3 M

VSS VSS VSS VDD12 VSS GPIO0/SIGDET0 TDP_0 TDN_0 N

VDD12A VDD12A VDD12A VDD33 VDD33 VSS RDP_0 RDN_0 P

RESERVED FIBR_DOP_1 FIBR_DIP_1 RDP_1 TDP_1 FIBR_DOP_0 FIBR_DIP_0 VSS R

RESERVED FIBR_DON_1 FIBR_DIN_1 RDN_1 TDN_1 FIBR_DON_0 FIBR_DIN_0 NC T



Pin Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 79

6.3 Pins by Function
This section contains the functional pin descriptions for the VSC8662 device.

6.3.1 GPIO  
The following table shows the pins associated with the device GPIO and SIGDET. 

6.3.2 JTAG
The following table lists the pins associated with the device JTAG testing facility.

ADIFF Analog differential Analog differential signal pair for twisted pair interface.

ABIAS Analog bias Analog bias pin.

IA Analog input Analog input for sensing variable voltage levels.

IPU5V Input with pull-up Input with on-chip pull-up resistor to VDD33. These pins are 
5 V tolerant.

OCRYST Crystal output Crystal clock output pin. If not used, leave unconnected.

NC No connect No connect pins must be left floating.

Table 90 • GPIO Pins

Name Pin Type Description
GPIO15
GPIO14
GPIO13
GPIO12
GPIO11
GPIO10
GPIO9/FastLinkFail
GPIO8/I2C_SDA
GPIO7
GPIO6
GPIO5/I2C_SCL_1
GPIO4/I2C_SCL_0
GPIO3
GPIO2
GPIO1/SIGDET_1
GPIO0/SIGDET_0

J16
J15
H14
J14
K16
K15
K14
K13
L16
L15
L14
L13
M16
M15
M14
N14

IPU/O General purpose input/output (GPIO). Ten dedicated 
GPIO pins are provided. Additionally, the fast link fail, 
two SIGDET pins, and three I2C controller pins can 
be configured to become GPIO pins if not used.

Table 91 • JTAG Pins

Name Pin Type Description
NTRST E3 IPU5V JTAG reset. When JTAG test operation is not in use, then 

tie this pin to VSS (ground) with a pull-down resistor for 
normal operation.

TCK F3 IPU5V JTAG test clock input.

TDI F2 IPU5V JTAG test serial data input.

TDO F1 OPU JTAG test serial data output.

TMS E2 IPU5V JTAG test mode select.

Table 89 • Pin Type Symbols (continued)

Symbol Pin Type Description



Pin Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 80

6.3.3 Miscellaneous Pins
The following table lists pins not associated with a particular interface or facility on the device.

Table 92 • Miscellaneous Pins

Name Pin Type Description
CLKOUT G15 O Clock output can be enabled or disabled. It outputs 

a reference clock frequency of 125 MHz. This pin 
is not active when NRESET is asserted. When 
disabled, the pin is held low.

CMODE7
CMODE6
CMODE5
CMODE4
CMODE3
CMODE2
CMODE1
CMODE0

E16
E15
D14
E14
F15
F14
G14
G13

IA Configuration mode (CMODE) pins. For more 
information, see CMODE, page 61.

LED3_[1:0]
LED2_[1:0]
LED1_[1:0]
LED0_[1:0]

H4, G4
H3, G3
H2, G2
H1, G1

O LED direct-drive outputs. All LEDs pins are active-
low. A serial LED stream can also be 
implemented. For more information about LED 
operation, see LED Mode Select, page 47.

Note: LEDbit_port, where port = PHY port 
number and bit = the particular LED 
for the port.

OSCEN D2 IPD Oscillator enable. This pin is sampled on the rising 
edge of NRESET. If high, then the on-chip 
oscillator circuit is enabled. If low (or left floating), 
the oscillator circuit is disabled and the device 
must be supplied with a 25 MHz or 125 MHz 
reference clock to the REFCLK pin

PLLMODE E1 IPD PLL mode input select. Sampled on power-up or 
reset. If PLLMODE is low, then REFCLK must be 
25 MHz. If PLLMODE is high, then REFCLK must 
be 125 MHz.
If using a crystal, PLLMODE must be pulled low.

RCVRD_CLK2
RCVRD_CLK1

G16
F16

O Clock output can be enabled or disabled and also 
output a clock frequency of 125 MHz or 25 MHz 
based on the selected active recovered media 
programmed for this pin. This pin is not active 
when NRESET or NSRESET is asserted. When 
disabled, the pin is held low.

REF_FILT D3 ABIAS Reference filter connects to an external 1 µF 
capacitor to analog ground.

REF_REXT D4 ABIAS Reference external connects to an external 2 kΩ 
(1%) resistor to analog ground.



Pin Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 81

6.3.4 Power Supply
The following table lists the device power supply pins.

RESERVED A2, A3, A4, A5, A6, 
A7, A8, A9, B2, B3, 
B4, B5, B6, B7, B8, 
B9, C10, D13, E13, 
F13, J1, J2, J3, J4, 
K1, K2, K3, K4, L1, 
L2, M1, N1, N4, P1, 
R2, R3, R4, R5, R6, 
R7, R8, R9, T2, T3, 
T4, T5, T6, T7, T8, 
T9

NC Leave these pins unconnected (floating).

NC A1, A16, T1, T16 NC These pins are no connects. Do not connect them 
together or to ground. Leave these pins 
unconnected (floating).

THERMDA H16 IA Thermal diode anode (p-junction).

THERMDC H15 IA Thermal diode cathode (n-junction). Connected 
internally to VSS

XTAL1/REFCLK D1 I Crystal oscillator input. If OSCEN = high then a 
25 MHz parallel resonant crystal with ±50 ppm 
frequency tolerance should be connected across 
XTAL1 and XTAL2. A 33 pF capacitor should also 
tie the XTAL1 pin to ground.
Reference clock input. If OSCEN=low, the clock 
input frequency can either be 25 MHz 
(PLLMODE=0) or 125 MHZ (PLLMODE is high).

XTAL2 C1 OCRYST Crystal oscillator output. The crystal should be 
connected across XTAL1 and XTAL2. A 33 pF 
capacitor should also tie the XTAL2 pin to ground. 
If not using a crystal oscillator, this output pin can 
be left floating if driving XTAL1/REFCLK with a 
reference clock.

Table 93 • Power Supply Pins

Name Pin Type Description
VDD12A C7, C8, C9, C13, P6, 

P7, P8, P9, P10, P11
1.2 V 1.2 V analog power requiring additional PCB power 

supply filtering

VDD33 C2, C4, C6, C11, C14, 
E4, H13, M13, P5, 
P12, P13

3.3 V General 3.3 V power supply

VDD12 E5, E12, F5, F12, G5, 
G12, H5, H12, J5, J12, 
K5, K12, L5, L12, M5, 
M12, N5, N12

1.2 V Internal digital logic

VDDIO P3, M4 3.3 V
2.5 V
1.8 V

I/O power supply

Table 92 • Miscellaneous Pins (continued)

Name Pin Type Description



Pin Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 82

Although certain function pins may not be used for a specific application, all power supply pins must be 
connected to their respective voltage input.

6.3.5 SerDes MAC Interface
The following table shows the pins associated with the device SerDes MAC interface.

VSS B1, B16, C3, C5, C12, 
D5, D6, D7, D8, D9, 
D10, D11, D12, E6, 
E7, E8, E9, E10, E11, 
F4, F6, F7, F8, F9, 
F10, F11, G6, G7, G8, 
G9, G10, G11, H6, H7, 
H8, H9, H10, H11, J6, 
J7, J8, J9, J10, J11, 
J13, K6, K7, K8, K9, 
K10, K11, L4, L6, L7, 
L8, L9, L10, L11, M6, 
M7, M8, M9, M10, 
M11, N6, N7, N8, N9, 
N10, N11, N13, P4, 
P14, R1, R16

0 V General device ground

Table 94 • Power Supply and Associated Function Pins

Pin
Nominal 
Voltage Associated Functional Pins

VDD33 3.3 V LED[3:0]_n, GPIO[15:0], JTAG (5), XTAL1, XTAL2, CMODE, 
TXVP_n, TXVN_n, REF_FILT, REF_REXT, RCVRD_CLK1, 
RCVRD_CLK2, CLKOUT

VDDIO 1.8 V, 2.5 V, 
3.3 V

MDC, MDIO, MDINTn, nRESET

VDD12A 1.2 V MAC_RDP/N_n, MAC_TDP/N_n

VDD12 1.2 V N/A (Internal Core Voltage)

Table 95 • SerDes MAC Interface Pins

Name Pin Type Description
RDP_1
RDP_0
RDN_1
RDN_0

R12
P15
T12
P16

ODIFF SerDes MAC receiver output pair.

TDP_1
TDP_0
TDN_1
TDN_0

R13
N15
T13
N16

IDIFF SerDes MAC transmitter input pair.

Table 93 • Power Supply Pins (continued)

Name Pin Type Description



Pin Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 83

6.3.6 SerDes Media Interface 
The following table shows the pins associated with the device SerDes media interface.

6.3.7 Serial Management Interface
The following table lists the device pins associated with the device serial management interface (SMI). 
Note that the pins in this table are referenced to VDDIO and can be set to a 1.8 V, 2.5 V, or 3.3 V power 
supply.

Table 96 • SerDes Media Interface Pins 

Signal Name Pin Type Description
FIBR_DIP_1
FIBR_DIP_0
FIBR_DIN_1
FIBR_DIN_0

R11
R15
T11
T15

IDIFF SerDes media receiver input pair.

FIBR_DOP_1
FIBR_DOP_0
FIBR_DON_1
FIBR_DON_0

R10
R14
T10
T14

ODIFF SerDes media transmitter output pair.

Table 97 • SMI Pins

Name Pin Type Description
MDC P2 IPU Management data clock. A 0 MHz to 12.5 MHz reference 

input is used to clock serial MDIO data into and out of the 
PHY.

MDIO N2 OD Management data input/output pin. Serial data is written 
or read from this pin bidirectionally between the PHY and 
Station Manager, synchronously on the positive edge of 
MDC. One external pull-up resistor is required at the 
Station Manager, and its value depends on the MDC clock 
frequency and the total sum of the capacitive loads from 
the MDIO pins.

MDINT1
MDINT0

N3
M2

OS/OD Management interrupt signal. Upon reset the device will 
configure these pins as active-low (open drain) or active-
high (open source) based on the polarity of an external 
10 kΩ resistor connection. These pins can be tied 
together in a wired-OR configuration with only a single 
pull-up or pull-down resistor.

NRESET M3 IPU Device reset. Active low input that powers down the 
device and sets all register bits to their default state.

NSRESET L3 IPU Device soft reset. Active low input that powers down the 
device. Although, the device is powered down any 
register bits that are sticky will retain their value.



Pin Descriptions

VMDS-10312 VSC8662 Datasheet Revision 4.3 84

6.4 Twisted Pair Interface
The following table lists the device pins associated with the device two-wire, twisted pair interface.

Table 98 • Twisted Pair Interface Pins

Name Pin Type Description
TXVPA_1
TXVPA_0

A10
A14

ADIFF TX/RX channel A positive signal

TXVNA_1
TXVNA_0

B10
B14

ADIFF TX/RX channel A negative signal

TXVPB_1
TXVPB_0

A11
A15

ADIFF TX/RX channel B positive signal

TXVNB_1
TXVNB_0

B11
B15

ADIFF TX/RX channel B negative signal

TXVPC_1
TXVPC_0

A12
C16

ADIFF TX/RX channel C positive signal

TXVNC_1
TXVNC_0

B12
C15

ADIFF TX/RX channel C negative signal

TXVPD_1
TXVPD_0

A13
D16

ADIFF TX/RX channel D positive signal

TXVND_1
TXVND_0

B13
D15

ADIFF TX/RX channel D negative signal



VMDS-10312 VSC8662 Datasheet Revision 4.3 85

Dual Port 10/100/1000BASE-T PHY and 100BASE-FX/1000BASE-X SerDes with 
Recovered Clock Outputs

6.5 Pins by Number
This section provides a numeric list of the VSC8662 device pins.

A1 NC

A2 RESERVED

A3 RESERVED

A4 RESERVED

A5 RESERVED

A6 RESERVED

A7 RESERVED

A8 RESERVED

A9 RESERVED

A10 TXVPA_1

A11 TXVPB_1

A12 TXVPC_1

A13 TXVPD_1

A14 TXVPA_0

A15 TXVPB_0

A16 NC

B1 VSS

B2 RESERVED

B3 RESERVED

B4 RESERVED

B5 RESERVED

B6 RESERVED

B7 RESERVED

B8 RESERVED

B9 RESERVED

B10 TXVNA_1

B11 TXVNB_1

B12 TXVNC_1

B13 TXVND_1

B14 TXVNA_0

B15 TXVNB_0

B16 VSS

C1 XTAL2

C2 VDD33

C3 VSS

C4 VDD33

C5 VSS

C6 VDD33

C7 VDD12A

C8 VDD12A

C9 VDD12A

C10 RESERVED

C11 VDD33

C12 VSS

C13 VDD12A

C14 VDD33

C15 TXVNC_0

C16 TXVPC_0

D1 XTAL1/REFCLK

D2 OSCEN

D3 REF_FILT

D4 REF_REXT

D5 VSS

D6 VSS

D7 VSS

D8 VSS

D9 VSS

D10 VSS

D11 VSS

D12 VSS

D13 RESERVED

D14 CMODE5

D15 TXVND_0

D16 TXVPD_0

E1 PLLMODE

E2 TMS

E3 NTRST

E4 VDD33

E5 VDD12

E6 VSS

E7 VSS

E8 VSS

E9 VSS

E10 VSS

E11 VSS

E12 VDD12

E13 RESERVED

E14 CMODE4

E15 CMODE6

E16 CMODE7

F1 TDO

F2 TDI

F3 TCK

F4 VSS

F5 VDD12

F6 VSS

F7 VSS

F8 VSS

F9 VSS

F10 VSS

F11 VSS

F12 VDD12

F13 RESERVED

F14 CMODE2

F15 CMODE3

F16 RCVRD_CLK1

G1 LED0_0

G2 LED1_0

G3 LED2_0

G4 LED3_0

G5 VDD12

G6 VSS

G7 VSS

G8 VSS

G9 VSS

G10 VSS

G11 VSS

G12 VDD12

G13 CMODE0

G14 CMODE1

G15 CLKOUT

G16 RCVRD_CLK2

H1 LED0_1

H2 LED1_1



VMDS-10312 VSC8662 Datasheet Revision 4.3 86

Pins by number (continued)

H3 LED2_1

H4 LED3_1

H5 VDD12

H6 VSS

H7 VSS

H8 VSS

H9 VSS

H10 VSS

H11 VSS

H12 VDD12

H13 VDD33

H14 GPIO13

H15 THERMDC

H16 THERMDA

J1 RESERVED

J2 RESERVED

J3 RESERVED

J4 RESERVED

J5 VDD12

J6 VSS

J7 VSS

J8 VSS

J9 VSS

J10 VSS

J11 VSS

J12 VDD12

J13 VSS

J14 GPIO12

J15 GPIO14

J16 GPIO15

K1 RESERVED

K2 RESERVED

K3 RESERVED

K4 RESERVED

K5 VDD12

K6 VSS

K7 VSS

K8 VSS

K9 VSS

K10 VSS

K11 VSS

K12 VDD12

K13 GPIO8/I2C_SDA

K14 GPIO9/FastLinkFail

K15 GPIO10

K16 GPIO11

L1 RESERVED

L2 RESERVED

L3 NSRESET

L4 VSS

L5 VDD12

L6 VSS

L7 VSS

L8 VSS

L9 VSS

L10 VSS

L11 VSS

L12 VDD12

L13 GPIO4/I2C_SCL_0

L14 GPIO5/I2C_SCL_1

L15 GPIO6

L16 GPIO7

M1 RESERVED

M2 MDINT0

M3 NRESET

M4 VDDIO 

M5 VDD12

M6 VSS

M7 VSS

M8 VSS

M9 VSS

M10 VSS

M11 VSS

M12 VDD12

M13 VDD33

M14 GPIO1/SIGDET1

M15 GPIO2

M16 GPIO3

N1 RESERVED

N2 MDIO

N3 MDINT1

N4 RESERVED

N5 VDD12

N6 VSS

N7 VSS

N8 VSS

N9 VSS

N10 VSS

N11 VSS

N12 VDD12

N13 VSS

N14 GPIO0/SIGDET0

N15 TDP_0

N16 TDN_0

P1 RESERVED

P2 MDC

P3 VDDIO

P4 VSS

P5 VDD33

P6 VDD12A

P7 VDD12A

P8 VDD12A

P9 VDD12A

P10 VDD12A

P11 VDD12A

P12 VDD33

P13 VDD33

P14 VSS

P15 RDP_0

P16 RDN_0

R1 VSS

R2 RESERVED

R3 RESERVED

R4 RESERVED

R5 RESERVED

R6 RESERVED

R7 RESERVED

R8 RESERVED

R9 RESERVED

R10 FIBR_DOP_1

R11 FIBR_DIP_1

R12 RDP_1

R13 TDP_1



VMDS-10312 VSC8662 Datasheet Revision 4.3 87

Pins by number (continued)

R14 FIBR_DOP_0

R15 FIBR_DIP_0

R16 VSS

T1 NC

T2 RESERVED

T3 RESERVED

T4 RESERVED

T5 RESERVED

T6 RESERVED

T7 RESERVED

T8 RESERVED

T9 RESERVED

T10 FIBR_DON_1

T11 FIBR_DIN_1

T12 RDN_1

T13 TDN_1

T14 FIBR_DON_0

T15 FIBR_DIN_0
T16 NC



VMDS-10312 VSC8662 Datasheet Revision 4.3 88

Dual Port 10/100/1000BASE-T PHY and 100BASE-FX/1000BASE-X SerDes with 
Recovered Clock Outputs

6.6 Pins by Name
This section provides an alphabetical list of the VSC8662 device pins.

CLKOUT G15

CMODE0 G13

CMODE1 G14

CMODE2 F14

CMODE3 F15

CMODE4 E14

CMODE5 D14

CMODE6 E15

CMODE7 E16

FIBR_DIN_0 T15

FIBR_DIN_1 T11

FIBR_DIP_0 R15

FIBR_DIP_1 R11

FIBR_DON_0 T14

FIBR_DON_1 T10

FIBR_DOP_0 R14

FIBR_DOP_1 R10

GPIO0/SIGDET0 N14

GPIO1/SIGDET1 M14

GPIO2 M15

GPIO3 M16

GPIO4/I2C_SCL_0 L13

GPIO5/I2C_SCL_1 L14

GPIO6 L15

GPIO7 L16

GPIO8/I2C_SDA K13

GPIO9/FastLinkFail K14

GPIO10 K15

GPIO11 K16

GPIO12 J14

GPIO13 H14

GPIO14 J15

GPIO15 J16

LED0_0 G1

LED0_1 H1

LED1_0 G2

LED1_1 H2

LED2_0 G3

LED2_1 H3

LED3_0 G4

LED3_1 H4

MDC P2

MDINT0 M2

MDINT1 N3

MDIO N2

NC A1

NC A16

NC T1

NC T16

NRESET M3

NSRESET L3

NTRST E3

OSCEN D2

PLLMODE E1

RCVRD_CLK1 F16

RCVRD_CLK2 G16

RDN_0 P16

RDN_1 T12

RDP_0 P15

RDP_1 R12

REF_FILT D3

REF_REXT D4

RESERVED A2

RESERVED A3

RESERVED A4

RESERVED A5

RESERVED A6

RESERVED A7

RESERVED A8

RESERVED A9

RESERVED B2

RESERVED B3

RESERVED B4

RESERVED B5

RESERVED B6

RESERVED B7

RESERVED B8

RESERVED B9

RESERVED C10

RESERVED D13

RESERVED E13

RESERVED F13

RESERVED J1

RESERVED J2

RESERVED J3

RESERVED J4

RESERVED K1

RESERVED K2

RESERVED K3

RESERVED K4

RESERVED L1

RESERVED L2

RESERVED M1

RESERVED N1

RESERVED N4

RESERVED P1

RESERVED R2

RESERVED R3

RESERVED R4

RESERVED R5

RESERVED R6

RESERVED R7

RESERVED R8

RESERVED R9

RESERVED T2

RESERVED T3

RESERVED T4

RESERVED T5

RESERVED T6

RESERVED T7

RESERVED T8

RESERVED T9

TCK F3

TDI F2



VMDS-10312 VSC8662 Datasheet Revision 4.3 89

Pins by name (continued)

TDN_0 N16

TDN_1 T13

TDO F1

TDP_0 N15

TDP_1 R13

THERMDA H16

THERMDC H15

TMS E2

TXVNA_0 B14

TXVNA_1 B10

TXVNB_0 B15

TXVNB_1 B11

TXVNC_0 C15

TXVNC_1 B12

TXVND_0 D15

TXVND_1 B13

TXVPA_0 A14

TXVPA_1 A10

TXVPB_0 A15

TXVPB_1 A11

TXVPC_0 C16

TXVPC_1 A12

TXVPD_0 D16

TXVPD_1 A13

VDD12 E5

VDD12 E12

VDD12 F5

VDD12 F12

VDD12 G5

VDD12 G12

VDD12 H5

VDD12 H12

VDD12 J5

VDD12 J12

VDD12 K5

VDD12 K12

VDD12 L5

VDD12 L12

VDD12 M5

VDD12 M12

VDD12 N5

VDD12 N12

VDD33 C2

VDD33 C4

VDD33 C6

VDD33 C11

VDD33 C14

VDD33 E4

VDD33 H13

VDD33 M13

VDD33 P5

VDD33 P12

VDD33 P13

VDD12A C7

VDD12A C8

VDD12A C9

VDD12A C13

VDD12A P6

VDD12A P7

VDD12A P8

VDD12A P9

VDD12A P10

VDD12A P11

VDDIO P3

VDDIO M4

VSS B1

VSS B16

VSS C3

VSS C5

VSS C12

VSS D5

VSS D6

VSS D7

VSS D8

VSS D9

VSS D10

VSS D11

VSS D12

VSS E6

VSS E7

VSS E8

VSS E9

VSS E10

VSS E11

VSS F4

VSS F6

VSS F7

VSS F8

VSS F9

VSS F10

VSS F11

VSS G6

VSS G7

VSS G8

VSS G9

VSS G10

VSS G11

VSS H6

VSS H7

VSS H8

VSS H9

VSS H10

VSS H11

VSS J6

VSS J7

VSS J8

VSS J9

VSS J10

VSS J11

VSS J13

VSS K6

VSS K7

VSS K8

VSS K9

VSS K10

VSS K11

VSS L4

VSS L6

VSS L7

VSS L8

VSS L9

VSS L10

VSS L11



VMDS-10312 VSC8662 Datasheet Revision 4.3 90

Pins by name (continued)

VSS M6

VSS M7

VSS M8

VSS M9

VSS M10

VSS M11

VSS N6

VSS N7

VSS N8

VSS N9

VSS N10

VSS N11

VSS N13

VSS P4

VSS P14

VSS R1

VSS R16

XTAL1/REFCLK D1
XTAL2 C1



Package Information

VMDS-10312 VSC8662 Datasheet Revision 4.3 91

7 Package Information

The VSC8662 device is offered with two operating temperature ranges. The operating temperature range 
for VSC8662 is 0 °C ambient to 90 °C case, and the range for VSC8662-03 is –40 °C ambient to 100 °C 
case.

VSC8662XIC and VSC8662XIC-03 are packaged in a lead-free (Pb-free), 256-pin, plastic ball grid array 
(BGA) with a 17 mm × 17 mm body size, 1 mm pin pitch, and 2 mm maximum height.

Lead-free products from Vitesse comply with the temperatures and profiles defined in the joint IPC and 
JEDEC standard IPC/JEDEC J-STD-020. For more information, see the IPC and JEDEC standard.

This section provides the package drawing, thermal specifications, and moisture sensitivity rating for the 
VSC8662 device.

7.1 Package Drawing
The following illustration shows the package drawing for the VSC8662 device. The drawing contains the 
top view, bottom view, side view, dimensions, tolerances, and notes.



Package Information

VMDS-10312 VSC8662 Datasheet Revision 4.3 92

Figure 27 • Package Drawing

A1 ball corner Ø 0.50(3×) Ref.

CA(4×)

M

N

P

N

M

T

R

H

G

F

L

K

J

B

A

E

D

C

716 14 1315 101112 89 56 234 1

D1

D

e

Ø 0.10  M   C
Ø 0.25  M   C  A  B

Ø b

B

A
0
.2

0
 (

4
×

)

E E1

e

0
.2

0
  

C

0
.3

5
  

C

A1

30°

ASeating planeC

0
.2

5
  

C

A2

A3

Dimensions

Reference Minimum Nominal Maximum

D
E
D1
E1
e

A

A3
A2
A1

b
M
N
CA

17.00
17.00
15.00
15.00
1.00

2.00

0.85 Ref.
0.56 Ref.

0.30 0.50

0.40 0.50 0.60
15.00
15.00

1.21 Ref.

Top View Bottom View

Side View

Notes
1.  All dimensions and tolerances are in mil l imeters (mm).
2.  Radial true position is represented by typical values.



Package Information

VMDS-10312 VSC8662 Datasheet Revision 4.3 93

7.2 Thermal Specifications
Thermal specifications for this device are based on the JEDEC standard EIA/JESD51-2 and have been 
modeled using a four-layer test board with two signal layers, a power plane, and a ground plane (2s2p 
PCB). For more information, see the JEDEC standard.

To achieve results similar to the modeled thermal resistance measurements, the guidelines for board 
design described in the JEDEC standard EIA/JESD51 series must be applied. For information about 
specific applications, see the following:

EIA/JESD51-5, Extension of Thermal Test Board Standards for Packages with Direct Thermal 
Attachment Mechanisms

EIA/JESD51-7, High Effective Thermal Conductivity Test Board for Leaded Surface Mount Packages

EIA/JESD51-9, Test Boards for Area Array Surface Mount Package Thermal Measurements

EIA/JESD51-10, Test Boards for Through-Hole Perimeter Leaded Package Thermal Measurements

EIA/JESD51-11, Test Boards for Through-Hole Area Array Leaded Package Thermal Measurements

7.3 Moisture Sensitivity
This device is rated moisture sensitivity level 3 or better as specified in the joint IPC and JEDEC standard 
IPC/JEDEC J-STD-020. For more information, see the IPC and JEDEC standard.

Table 99 • Thermal Resistances

θJA (°C/W) vs. Airflow (ft/min)
Part Order Number θJC θJB 0 100 200
VSC8662XIC 7.5 11.2 21.9 20.4 19.4

VSC8662XIC-03 7.5 11.2 21.9 20.4 19.4



Design Considerations

VMDS-10312 VSC8662 Datasheet Revision 4.3 94

8 Design Considerations

This section provides design guidelines for the VSC8662 device.

8.1 Required Device Configuration
After initial NRESET deassertion or any time NSRESET is deasserted, the following script must be run to 
correctly configure the part:

PhyWrite(BasePortNo + 2, 31, 0x0000);

PhyWrite(BasePortNo + 2, 0, 0x0800);

PhyWrite(BasePortNo + 3, 31, 0x0000);

PhyWrite(BasePortNo + 3, 0, 0x0800);

If a broadcast write is made to MII register 0 that either sets bit 15 or clears bit 11, the preceding script 
must be re-run afterwards.

8.2 Broadcast Writes
Because the scripts to implement the workarounds in this section need to be written to all ports of the 
device, the broadcast write feature is useful to reduce the time to initialize the device. Broadcast writes 
do not apply across multiple VSC8662 devices on a single SMI bus (for example, you must perform the 
broadcast write to each device).

Note that broadcast writes are enabled by setting register bit 22.0 in any one of the two ports in a given 
VSC8662 device. They may be disabled by clearing the bit in any one of the two ports in the same 
device.

Command format:

PhyWrite( PortNo, Register (dec), 16_bit_unsigned_data(hex) );
16_bit_unsigned_data = PhyRead( PortNo, Register (dec) );

To enable broadcast writes, precede the sequence of initialization scripts with the following script:

PhyWrite(PortNo, 31, 0x0000 ); // Goto Mii Register Page
MiiReg22 = PhyRead(PortNo, 22 ); // Read MiiReg22
MiiReg22 = (MiiReg22 | 0x0001); //Enable broadcast write
PhyWrite(PortNo, 22, MiiReg22 ); //Write MiiReg22

To disable broadcast writes, use the following script after the sequence of initialization scripts:

MiiReg22 = (MiiReg22 & 0xfffe); //Disable broadcast write
PhyWrite(PortNo, 22, MiiReg22 ); //Write MiiReg22

8.3 Enabling LED Blinking After Reset 
Issue: To enable LED blinking after reset de-assertion, a software sequence must be run. Setting the 
register alone (register 19E, bit 11) does not enable the feature. In contrast, other Vitesse Ethernet PHY 
devices enable this feature either through the register setting or through a CMODE pin.

Implications: LEDs will not blink after reset de-assertion unless the feature is initialized as shown in the 
following script.

Workaround: Use the following script to change the value of the LED blink configuration register (address 
19E, bit 11) on all ports and then perform a soft reset on all ports. 



Design Considerations

VMDS-10312 VSC8662 Datasheet Revision 4.3 95

Command format:

PhyWrite( PortNo, Register (dec), 16_bit_unsigned_data(hex) );
16_bit_unsigned_data = PhyRead( PortNo, Register (dec) );

On hardware initialization, run the following:

PhyWrite( PortNo, 31, 0x0001 ); // Goto ExtMii Register Page
ExtReg19 = PhyRead(PortNo, 19); //Read ExtReg19
ExtReg19 = (ExtReg19 | 0x0800); //Enable LED blink for 1 second
PhyWrite( PortNo, 19, ExtReg19 ); //Write ExtReg19

After enabling LED blink after reset, you can assert and de-assert the NSRESET pin on the device to 
complete the soft reset. Using the NSRESET pin allows the LED blink to be synchronized across multiple 
VSC8662 devices. Alternatively, the following soft reset script may be issued to each VSC8662 port:

PhyWrite( 0, 31, 0x0000 ); // Goto Mii Register Page
PhyWrite( 0, 0, 0x9040 ); // Perform soft reset

8.4 100/1000BASE-T Amplitude Compensation 
Issue: The 100BASE-TX and 1000BASE-T amplitudes must be increased to meet specifications. 

Implications: If uncompensated, the 100BASE-TX and 1000BASE-T transmission is at reduced 
amplitude.

Workaround: Use the following script to adjust the 100BASE-TX and 1000BASE-T transmitter amplitude.

Command format:

PhyWrite( PortNo, Register (dec), 16_bit_unsigned_data(hex) );
16_bit_unsigned_data = PhyRead( PortNo, Register (dec) );

On hardware initialization, run the following:

PhyWrite( PortNo, 31, 0x2a30);
Reg24 = PhyRead(PortNo, 24 );
Reg24 = ((Reg24 & 0xfffb ) | 0x0003 );
PhyWrite( PortNo, 24, Reg24 );
PhyWrite( PortNo, 31, 0x0000);
Reg24 = PhyRead(PortNo, 24 );
Reg24 = ((Reg24 & 0xfff5 ) | 0x0004 );
PhyWrite( PortNo, 24, Reg24 );

8.5 Increase 10BASE-T Performance
Issue: In order to ensure robust performance of 10BASE-T links, an initialization script should be 
performed.

Workaround: Use the following script on hardware initialization.

PhyWrite( PortNo, 31, 0x52b5 );
PhyWrite( PortNo, 18, 0x0 );
PhyWrite( PortNo, 17, 0x3f );
PhyWrite( PortNo, 16, 0x8794 );

PhyWrite( PortNo, 18, 0xf7 );
PhyWrite( PortNo, 17, 0xadb4 );
PhyWrite( PortNo, 16, 0x879e );



Design Considerations

VMDS-10312 VSC8662 Datasheet Revision 4.3 96

PhyWrite( PortNo, 18, 0x0 );
PhyWrite( PortNo, 17, 0x32 );
PhyWrite( PortNo, 16, 0x87a0 );

PhyWrite( PortNo, 18, 0x41 );
PhyWrite( PortNo, 17, 0x410 );
PhyWrite( PortNo, 16, 0x87a2 );

PhyWrite( PortNo, 18, 0x41 );
PhyWrite( PortNo, 17, 0x410 );
PhyWrite( PortNo, 16, 0x87a4 );

PhyWrite( PortNo, 18, 0x41 );
PhyWrite( PortNo, 17, 0x284 );
PhyWrite( PortNo, 16, 0x87a6 );

PhyWrite( PortNo, 18, 0x92 );
PhyWrite( PortNo, 17, 0xbcb8 );
PhyWrite( PortNo, 16, 0x87a8 );

PhyWrite( PortNo, 18, 0x3 );
PhyWrite( PortNo, 17, 0xcfbf );
PhyWrite( PortNo, 16, 0x87aa );

PhyWrite( PortNo, 18, 0x49 );
PhyWrite( PortNo, 17, 0x2451 );
PhyWrite( PortNo, 16, 0x87ac );

PhyWrite( PortNo, 18, 0x1 );
PhyWrite( PortNo, 17, 0x1410 );
PhyWrite( PortNo, 16, 0x87c0 );

PhyWrite( PortNo, 18, 0x10 );
PhyWrite( PortNo, 17, 0xb498 );
PhyWrite( PortNo, 16, 0x87e8 );

PhyWrite( PortNo, 18, 0x71 );
PhyWrite( PortNo, 17, 0xe7dd );
PhyWrite( PortNo, 16, 0x87ea );

PhyWrite( PortNo, 18, 0x69 );
PhyWrite( PortNo, 17, 0x6512 );
PhyWrite( PortNo, 16, 0x87ec );

PhyWrite( PortNo, 18, 0x49 );
PhyWrite( PortNo, 17, 0x2451 );
PhyWrite( PortNo, 16, 0x87ee );

PhyWrite( PortNo, 18, 0x45 );
PhyWrite( PortNo, 17, 0x410 );
PhyWrite( PortNo, 16, 0x87f0 );

PhyWrite( PortNo, 18, 0x41 );
PhyWrite( PortNo, 17, 0x410 );
PhyWrite( PortNo, 16, 0x87f2 );



Design Considerations

VMDS-10312 VSC8662 Datasheet Revision 4.3 97

PhyWrite( PortNo, 18, 0x0 );
PhyWrite( PortNo, 17, 0x10 );
PhyWrite( PortNo, 16, 0x87f4 );

PhyWrite( PortNo, 31, 0x2a30);
Reg9 = PhyRead(PortNo, 9 );
Reg9 = ((Reg9 & 0xffff ) | 0x0040 );
PhyWrite( PortNo, 9, Reg9 );
//PhyWrite( PortNo, 31, 0x0000);

Reg22 = PhyRead(PortNo, 22 );
Reg22 = ((Reg22 & 0xffff ) | 0x0010 );
PhyWrite( PortNo, 22, Reg22 );
PhyWrite( PortNo, 31, 0x0000);

8.6 Performance Optimization for 100BASE-TX and 
1000BASE-T Slave
Issue: To improve start-up reliability on the longest cables, an initialization sequence must be run. This 
initialization configures the receiver for optimal reach in both 1000BASE-T slave and 100BASE-TX 
operating modes.

Implications: If not optimized, 100BASE-TX and 1000BASE-T links over a 100 m or longer cable may fail 
to come up.

Workaround: Use the following script to optimize these links. This can be run once during hardware 
initialization regardless of the operating speed.

PhyWrite( PortNo, 31, 0x2a30);
Reg0 = PhyRead(PortNo, 0 );
Reg0 = ((Reg0 & 0xffef ) | 0x0060 );
PhyWrite( PortNo, 0, Reg0 );

PhyWrite( PortNo, 31, 0x52b5 );
PhyWrite( PortNo, 18, 0x12 );
PhyWrite( PortNo, 17, 0x480a );
PhyWrite( PortNo, 16, 0x8f82 );

PhyWrite( PortNo, 18, 0x0 );
PhyWrite( PortNo, 17, 0x422 );
PhyWrite( PortNo, 16, 0x8f86 );

PhyWrite( PortNo, 18, 0x3c );
PhyWrite( PortNo, 17, 0x3800 );
PhyWrite( PortNo, 16, 0x8f8a );

PhyWrite( PortNo, 18, 0x8 );
PhyWrite( PortNo, 17, 0xe33f );
PhyWrite( PortNo, 16, 0x83ae );
PhyWrite( PortNo, 31, 0x0000);

8.7 Enable SGMII Version 1.8
Issue: By default, the SGMII version supported is 1.7. 

Implications: SGMII version 1.8 is not enabled by default.

Workaround: To enable SGMII version 1.8, set register 20E, bit 15 = 1.



Design Considerations

VMDS-10312 VSC8662 Datasheet Revision 4.3 98

8.8 Disabling Recovered Clock Output
Issue: When the recovered clock output is disabled by setting bit 15 to 0 in either register 23G or register 
24G, the recovered clock output pins (RCVRD_CLK1 or RCVRD_CLK2) are not disabled.

Implications: The recovered clock output is not disabled by setting only bit 15 in register 23G or register 
24G.

Workaround: To disable the recovered clock output, clear bit 15, and change the state of the selected 
PHY port in bit12, the clock frequency in bit 8, or the clock selection in bits 1:0.



Ordering Information

VMDS-10312 VSC8662 Datasheet Revision 4.3 99

9 Ordering Information

The VSC8662 device is offered with two operating temperature ranges. The operating temperature range 
for VSC8662 is 0 °C ambient to 90 °C case, and the range for VSC8662-03 is –40 °C ambient to 100 °C 
case.

VSC8662XIC and VSC8662XIC-03 are packaged in a lead-free (Pb-free), 256-pin, plastic ball grid array 
(BGA) with a 17 mm × 17 mm body size, 1 mm pin pitch, and 2 mm maximum height.

Lead-free products from Vitesse comply with the temperatures and profiles defined in the joint IPC and 
JEDEC standard IPC/JEDEC J-STD-020. For more information, see the IPC and JEDEC standard.

The following table lists the ordering information for the VSC8662 device.

Table 100 • Ordering Information

Part Order Number Description
VSC8662XIC Lead-free, 256-pin plastic BGA with a 17 mm × 17 mm body size, 1 mm pin 

pitch, and 2 mm maximum height. The operating temperature is 0 °C 
ambient to 90 °C case.

VSC8662XIC-03 Lead-free, 256-pin plastic BGA with a 17 mm × 17 mm body size, 1 mm pin 
pitch, and 2 mm maximum height. The operating temperature is –40 °C 
ambient to 100 °C case.


	1 Revision History
	1.1 Revision 4.3
	1.2 Revision 4.2
	1.3 Revision 4.1
	1.4 Revision 4.0
	1.5 Revision 2.0

	2 Overview
	2.1 Key Features
	2.2 Block Diagram

	3 Functional Descriptions
	3.1 Operating Modes
	3.2 SerDes MAC Interface
	3.2.1 SerDes MAC
	3.2.2 SGMII MAC

	3.3 SerDes Media Interface
	3.3.1 SerDes Media with PCS Auto-Negotiation
	3.3.2 SerDes Pass-Through Mode
	3.3.3 SGMII MAC-to-100BASE-FX Mode
	3.3.4 Unidirectional Transport for Fiber Media

	3.4 Advanced SerDes Features
	3.4.1 SerDes Receiver Equalization
	3.4.2 SerDes Transmitter Amplitude Control
	3.4.3 SerDes Link Integrity Information

	3.5 Cat5 Twisted Pair Media Interface
	3.5.1 Voltage-Mode Line Driver
	3.5.2 Cat5 Auto-Negotiation and Parallel Detection
	3.5.3 Automatic Crossover and Polarity Detection
	3.5.4 Manual MDI/MDI-X Setting
	3.5.5 Link Speed Downshift

	3.6 Automatic Media-Sense (AMS) Interface Mode
	3.7 Transformerless Ethernet
	3.8 Ethernet Inline Powered Devices
	3.9 IEEE 802.3af PoE Support
	3.10 ActiPHY Power Management
	3.10.1 Low Power State
	3.10.2 Link Partner Wake-up State
	3.10.3 Normal Operating State

	3.11 Media Recovered Clock Outputs
	3.11.1 Clock Selection Settings
	3.11.2 Clock Output Squelch

	3.12 Fast Link Failure Indication
	3.13 Serial Management Interface
	3.13.1 SMI Frames
	3.13.2 SMI Interrupts

	3.14 LED Interface
	3.14.1 LED Modes
	3.14.2 Extended LED Modes
	3.14.3 LED Behavior
	3.14.4 Serial LED Mode
	3.14.5 LED Port Swapping

	3.15 Integrated Two-Wire Serial Multiplexer
	3.15.1 Read/Write Access Using the Two-Wire Serial Mux

	3.16 GPIO Pins
	3.17 Testing Features
	3.17.1 Ethernet Packet Generator (EPG)
	3.17.2 CRC Counters
	3.17.3 Far-End Loopback
	3.17.4 Near-End Loopback
	3.17.5 Connector Loopback
	3.17.6 SerDes Loopbacks
	3.17.7 VeriPHY Cable Diagnostics
	3.17.8 IEEE 1149.1 JTAG Boundary Scan
	3.17.9 JTAG Instruction Codes
	3.17.10 Boundary Scan Register Cell Order
	3.17.11 IEEE 1149.6 AC-JTAG Boundary Scan Interface


	4 Configuration
	4.1 Registers
	4.1.1 Reserved Registers
	4.1.2 Reserved Bits

	4.2 IEEE Standard and Main Registers
	4.2.1 Mode Control
	4.2.2 Mode Status
	4.2.3 Device Identification
	4.2.4 Auto-Negotiation Advertisement
	4.2.5 Link Partner Auto-Negotiation Capability
	4.2.6 Auto-Negotiation Expansion
	4.2.7 Transmit Auto-Negotiation Next Page
	4.2.8 Auto-Negotiation Link Partner Next Page Receive
	4.2.9 1000BASE-T Control
	4.2.10 1000BASE-T Status
	4.2.11 1000BASE-T Status Extension 1
	4.2.12 100BASE-TX Status Extension
	4.2.13 1000BASE-T Status Extension 2
	4.2.14 Bypass Control
	4.2.15 Error Counter 1
	4.2.16 Error Counter 2
	4.2.17 Error Counter 3
	4.2.18 Extended Control and Status
	4.2.19 Extended PHY Control Set 1
	4.2.20 Extended PHY Control Set 2
	4.2.21 Interrupt Mask
	4.2.22 Interrupt Status
	4.2.23 MAC Interface Auto-Negotiation Control and Status
	4.2.24 Device Auxiliary Control and Status
	4.2.25 LED Mode Select
	4.2.26 LED Behavior

	4.3 Extended Page Registers
	4.3.1 Extended Page Access
	4.3.2 SerDes Media Control
	4.3.3 SerDes MAC/Media Control
	4.3.4 CRC Good Counter
	4.3.5 SerDes Loopback and SIGDET Control
	4.3.6 ActiPHY Control
	4.3.7 PoE and Miscellaneous Functionality
	4.3.8 SerDes MAC/Media Status
	4.3.9 Ethernet Packet Generator Control 1
	4.3.10 Ethernet Packet Generator Control 2

	4.4 General-Purpose I/O Registers
	4.4.1 Reserved GPIO Address Space
	4.4.2 SIGDET vs. GPIO Control
	4.4.3 GPIO Input
	4.4.4 GPIO Output
	4.4.5 GPIO Pin Configuration
	4.4.6 Fast Link Fail Control
	4.4.7 Two-Wire Serial Mux Control 1
	4.4.8 Two-Wire Serial Mux Control 2
	4.4.9 Two-Wire Serial Mux Data Read/Write
	4.4.10 Recovered Clock 1
	4.4.11 Recovered Clock 2
	4.4.12 LED Port Swapping

	4.5 CMODE
	4.5.1 CMODE Pins and Related Functions
	4.5.2 Functions and Related CMODE Pins
	4.5.3 CMODE Resistor Values


	5 Electrical Specifications
	5.1 DC Characteristics
	5.1.1 VDDIO at 3.3 V
	5.1.2 VDDIO at 2.5 V
	5.1.3 VDDIO at 1.8 V
	5.1.4 VDD33 at 3.3 V
	5.1.5 DC Characteristics for MAC and SerDes Media Outputs
	5.1.6 DC Characteristics for MAC and SerDes Media Inputs
	5.1.7 LED Pins
	5.1.8 JTAG Pins

	5.2 Current Consumption
	5.3 AC Characteristics
	5.3.1 Reference Clock Input
	5.3.2 Clock Output
	5.3.3 Recovered Clock Outputs
	5.3.4 AC Characteristics for MAC and SerDes Media Outputs
	5.3.5 AC Characteristics for MAC and SerDes Media Inputs
	5.3.6 JTAG Interface
	5.3.7 SMI Interface
	5.3.8 Device Reset
	5.3.9 Serial LEDs

	5.4 Operating Conditions
	5.5 Stress Ratings

	6 Pin Descriptions
	6.1 Pin Diagram
	6.2 Pin Identifications
	6.3 Pins by Function
	6.3.1 GPIO
	6.3.2 JTAG
	6.3.3 Miscellaneous Pins
	6.3.4 Power Supply
	6.3.5 SerDes MAC Interface
	6.3.6 SerDes Media Interface
	6.3.7 Serial Management Interface

	6.4 Twisted Pair Interface
	6.5 Pins by Number
	6.6 Pins by Name

	7 Package Information
	7.1 Package Drawing
	7.2 Thermal Specifications
	7.3 Moisture Sensitivity

	8 Design Considerations
	8.1 Required Device Configuration
	8.2 Broadcast Writes
	8.3 Enabling LED Blinking After Reset
	8.4 100/1000BASE-T Amplitude Compensation
	8.5 Increase 10BASE-T Performance
	8.6 Performance Optimization for 100BASE-TX and 1000BASE-T Slave
	8.7 Enable SGMII Version 1.8
	8.8 Disabling Recovered Clock Output

	9 Ordering Information
