AM79C875KC datasheet(46/48 Pages) AMD

46 / 48 page

Am79C875

ERRATA

NetPHY™ 4LP Revision B.4 is the current production revision silicon with errata – please refer to the descriptions

below.

Revision B.4 Errata Summary

The NetPHY™ 4LP device has a total of 5 errata, all of which are minor and should not cause concern. All informa-

tion below should be used in conjunction with the NetPHY™ 4LP Final Datasheet PID 22236, available on the AMD

web site (www.amd.com).

Errata for NetPHY™ 4LP B.4

The SYMPTOM section gives an external description of the problem. The IMPLICATION section explains how the

device behaves and its impact on the system. The WORKAROUND section describes a workaround for the problem.

The STATUS section indicates when and how the problem will be fixed.

B4.1) 10BASE-T signal acceptance compliance test suite - test #1411.11.03

SYMPTOM:

CRS response to Signal 7a, 7b, 8a, 8b and 10 is unreliable unless the signal is preceded by a

preamble.

IMPLICATION:

These compliance tests reflect boundary conditions unlikely to happen in normal operation.

Some boundary conditions are meant to test the receiver's robustness and if it properly receives

valid data. We have successfully received 10Mbps data for all cable lengths, and we believe

that the chance of failure in the field is extremely low.

WORKAROUND:

There is no external work around.

STATUS:

This errata will not be fixed.

B4.2) 10BASE-T Local Loopback

SYMPTOM:

10BASE-T Local loopback does not work.

IMPLICATION:

This is a minor issue which does not affect normal operation.

WORKAROUND:

Loopback testing must be performed external to the device.

STATUS:

This errata will not be fixed.

B4.3) 10Mb not interrupted by 100Mb data reception

SYMPTOM:

If the PHY is in 10BASE-T and for an unknown reason, 100Mbps data is received, the PHY

should drop 10Mb link and establish 100Mb link.

IMPLICATION:

This is a minor issue which should not affect normal operation. This is UNH test 25.28c, where

it is stated that the standard does not allow for this behavior and that no harm to the network is

anticipated. Additionally, it is not uncommon to find this issue with many PHYs today.

WORKAROUND:

There is no external workaround.

STATUS:

This errata will not be fixed.

B4.4) Delayed idle following abnormal packet transmission

SYMPTOM:

If a packet does not end in a /T/R/, the RX_ER signal does not go true immediately after, and

is delayed 1 to 2 clock cycles. The receiver will then enter the idle state.

IMPLICATION:

This is a minor issue. If the packet does not terminate properly, RX_ER is delayed 1-2 clock

cycles. The issue is believed to be minor since the likelihood of encountering improperly termi-

nated data packets is small. However, it will affect the recording of errors by the system. (UNH

1.24)

WORKAROUND:

There is no external workaround.

STATUS:

This errata will not be fixed.

AM79C875KC Datasheet(PDF) 46 Page - Advanced Micro Devices

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