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DP83848K: Urgent, EMI issue for DP83848K

Lin Zhao
Intellectual 1230 points
Part Number: DP83848K

Hello,

I'd like to bring your attention on this urgent case, it's EMI issue for DP83848, customer failed the test for 125MHZ 375MHZ, these two points, and it's sure that it's the issue from this device, since after remove DP83848 from board, issue is gone, here I attached the schematic and layout for review.

And since the internal ossillator is 125Mhz, we suspect it's the noise source, pls kindly review the file and give suggestion, thank you.

11.pdf

TX_CLK waveform as below

  • 0
    TI__Mastermind 23675 points
    Hi Lin,

    The MDI (TD+/- and RD+/-) do not look like they are routed with 100 ohm differential impedance.
    TD+ and TD- should have 100 ohm control since the channel is designed to that impedance.
    Same is true for RD+ and RD-.

    I can see that there is metal near both differential pairs, which will change the impedance as well as large separation between them for routing to the RJ45.