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DP83TC812R-Q1: DP83TC812 LOW PASS Filter

Kung Poyuan
Prodigy 221 points
Part Number: DP83TC812R-Q1
Other Parts Discussed in Thread: DP83TC811

Tool/software:

HI TI Teams

When the Ethernet PHY was changed from DP83TC811 to DP83TC812, the output low-pass filter design was removed as recommended.
However, due to poorer emissions measurement results with DP83TC812, the following questions arise:

A. Can the original low-pass filter design be reintroduced for DP83TC812?
B. If the original low-pass filter design is reintroduced, will it affect the Ethernet signal quality?

  • 0
    TI__Mastermind 24531 points

    Hi Kung,

    The DP83TC811 low pass filter should not be populated for DP83TC812 as ethernet signal quality will be affected. Can you please share the emissions results with me? 

    Thanks,

    David 

  • 0 in reply to David Creger
    Prodigy 20 points

    Hi David

    The EMI issue is being measured (conducted) on the DP83TC812’s TRD_P and TRD_M.

    Do you have any recommended filters or noise-reduction design suggestions?

    The attached file shows the test results.When the TRD_P and TRD_M lines are connected, conducted noise is detected

  • 0 in reply to TING LIN WANG
    TI__Mastermind 24531 points

    Hi Ting,

    Can you share setup pictures of this test? I see you are testing according to ENS0310, which I am not familiar with. Could you share the end equipment/OEM for this project? 

    Emissions can be affected by schematic and/or layout design. Can you please share your schematic/layout with me to review?

    Thanks,

    David