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DP83TC811S-Q1: unlink issue of DP83TC811S-Q1

Betty Guo
Expert 7300 points
Part Number: DP83TC811S-Q1

Hi team,

my customer test DP83TC811S-Q1, some times it will report unlink issue. the PHY ID is correct.

below is test waveform:

Issues:

1. why the PHY device sometime is link while sometimes is unlink in ID correct condition?

2. for reg 0x01, 0x02 and 0x03 value, I think it should be fix value, but read it found they will be change.

thanks.

  • 0
    TI__Genius 16030 points

    Hi Betty,

    Yes registers 0x02 (value = x2000) and register 0x03 (value = 0xA253)  should have the fixed values always. Does this wrong value read happens when you see link-up issue? Is there any other device connected on MDC/MDIO bus (if yes we may confirm that its phy address is different)?

    Can you please check if the power up timing sequence is ok (as per datasheet)? You may also check if during the issue case does pin reset recovers the issue.

    At present my suspicion is :

    1. Some issue with power sequence : may be 25MHz clock not stable before supplies are up.

    2. Some clash on MDC/MDIO bus because of other connected device.

    --

    Regards,

    Vikram