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DP83TC811-Q1: Regarding the compliance test "100BASET1_IOP_24a, 100BASET1_IOP_24b"

Hiroaki Yuyama TED
Expert 1720 points
Part Number: DP83TC811-Q1

Tool/software:

Dear, Interface Support team.

Our customer conducted the compliance tests for 100BASET1_IOP_24a and 100BASET1_IOP_24b.

We have two questions for TI regarding the signal quality indication (SQI) that was included in the tests.

We have compiled the customer's questions in a PowerPoint file.
DP83TC811 Regarding the compliance test.pptx
Best Regards,
Hiroaki Yuyama

  • 0
    TI__Mastermind 26782 points

    Hi Hiroaki,

    Where was the "SQI expected" curve obtained from? We can share the TI compliance report but only under NDA. Please reach out to your local field applications engineer if this is required.

    Can you please share the customer schematic with me? As well as images of the customer's setup which is used to measure SQI. Has this measurement been reproducible on multiple boards?

    I see the X axis on the graph only goes as low as 100mV. What is the SQI value when noise amplitude is 0mV? Is it still 5?

    Thanks,

    David

  • 0 in reply to David Creger
    Expert 1720 points

    Hi David-san
    Thank you for your reply.
    We have received customer feedback on your question.


    1.This is the reference curve displayed when performing the 100BASE-T1 (TC8) standard compliance test [OABR_SIGNAL_01, OABR_SIGNAL_02] using the "Automotive Ethernet Test Application" provided by KEYSIGHT.

    2.I will share the circuit diagram and a photo taken during measurement.

    DP83TC811-Q1 schematic.xlsx
    Only one measurement was taken.
    In addition, under different conditions,    when checking the SQI value on multiple boards under normal conditions without applying noise, the maximum value was 5.
    Since the test circuit has a long distance (about 20 cm) MDI signal line, we plan to revise it and shorten the MDI signal line.

    3.The X axis of the graph seems to only go down to 100 mV.

    What is the SQI value when the noise amplitude is 0 mV? Is it still 5?
    →The SQI value was 5 even when no noise was applied (0 mV).

    Best Regards,
    Hiroaki Yuyama
  • 0 in reply to Hiroaki Yuyama TED
    TI__Mastermind 26782 points

    Hi Hiroaki-san,

    I see you are using a multi-board solution, utilizing a board-to-board connector. However I noticed there is CMC and CM termination on both boards. Recommended solution is to use only one CMC and CM termination, other design may affect the signal quality and SQI measurement. Is my understanding correct?

    Thanks,

    David

  • 0 in reply to David Creger
    Expert 1720 points

    Hi David-san,

    Thank you for your any advice.

    I received feedback from a customer.

    I checked the SQI value without implementing the Common Mode Chok [FL16] and CM termination [C62, C66, R160, R164] on the PHY side and without applying noise, but it remained at 5.

    Could you tell me if there are any other parts that affect the signal quality?

    Best Regards,
    Hiroaki Yuyama

  • 0 in reply to Hiroaki Yuyama TED
    TI__Mastermind 26782 points

    Hi Hiroaki-san,

    Are you loading the script given in SNLA293?

    We recommend performing PMA compliance testing to validate the transmitter performance. Have you done this? 

    The multi-board solution has the potential to degrade the MDI signal integrity, so SQI of 5 may be expected in this case.

    Thanks,

    David

  • 0 in reply to David Creger
    Expert 1720 points

    Hi David-san,

    Thank you for your any advice.

    I've sent your advice to the customer.
    I haven't heard any feedback yet, but I think they're working on resolving the issue.
    I will reply to you if I get any feedback from the customer.

    Best Regards,
    Hiroaki Yuyama

    • 0 in reply to Hiroaki Yuyama TED
      TI__Mastermind 26782 points

      Hi Hiroaki-san,

      Thanks, let me know when you hear back.

      Regards,

      David