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DP83TC811S-Q1: Communication is abnormal (completely lost the package) when doing RI test with 2GHz interference

Amelie Zheng
Genius 10865 points
Part Number: DP83TC811S-Q1

Hi Team,

My customer now use DP83TC811S-Q1 and met some issue when doing RI test.

In RI test ,At the range of 1.9~ 2.3Ghz, pin communication is abnormal (completely lost the package). When interference are removed, pin communication immediately returned to normal.

  • PHY's clock and T1 working frequency are very low. However the interference signals is nearly 2GHz, which should not have an impact on PHY and cause communication problems. So why communication is abnormal.
  • Is there any way to read the state of PHY when it works abnormal so that we can locate where the problem is?

Thanks!

  • 0 in reply to Amelie Zheng
    TI__Genius 11725 points

    Hi Amelie,

    Which standard are you testing? You may read registers for PHY status. Can you provide a register dump? 

    Thank you,

    Nikhil

  • 0 in reply to Nikhil Menon
    TI__Genius 10865 points

    HI Nikhil,

    Thanks for your reply. 

    This is one of the EMI test standard-Radiation Immunity Test.

    I have asked customer to offer the resister dump and will update as soon as possible.

    May I ask whether it may because SGMII working frequency is 1.2GHz? So during the RI test , at the range of 1.9~ 2.3Ghz, pin communication is abnormal (completely lost the package). 

    How can we strengthen SGMII's drive output capability?

    Looking forward to your reply! Thanks!

  • 0 in reply to Amelie Zheng
    TI__Genius 11725 points

    Hi Amelie,

    Are there any exposed traces or headers? When you say "communication is abnormal (completely lost package)" does that mean link was completely dropped? Or is link still on and packets are being dropped? 

    Can you share the exact EM test standard and energy level?

    Thank you,

    Nikhil

  • 0 in reply to Nikhil Menon
    TI__Genius 10865 points

    Hi Nikhil,

    Here is the register dump.

            reg_0x09 = 0x3000;

            reg_0x12 = 0x00ff;

            reg_0x13 = 0x00cf;

            reg_0x018b = default & 0xfffc;

            reg_0x4a0 = 0x08a1;

    Other register is Default Setting.

    I also compare it with datasheet description, and it is normal setting...I think.

    What about your opinion?

  • 0 in reply to Nikhil Menon
    Prodigy 40 points

    HI Nikhil,

    In the previous test, we didn't obtain any traces, so we cann't confirm whether the DP83TC811S-Q1‘s link is still on now when "communication is abnormal (completely lost package)" .

    We plan to grab some traces in the next test. But before our next test, can you give us some hardware or software suggestions about the DP83TC811S-Q1‘s link was completely dropped or link still on but packets are being dropped, so that we can try to verify in the next test.

    The EMI test standard that we used is according to the standards of SAIC MAXUS and BORGWARD. The energy level is 100V/m.

    Thanks!

  • 0 in reply to Zekun Wang
    TI__Genius 11725 points

    Hi Amelie,

    Scope shots will be useful if obtainable. When I said are there any exposed traces, I was referring to pcb signal traces. If there are any exposed PCB traces, they could be vulnerable to interference. Do you have access to the MDIO/MDC pins while testing? 

    Can you share a schematic with us?

    Thank you,

    Nikhil