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DP83TC811S-Q1: BCI(Bulk Current Injection) test fault

Sherry Liang
Genius 10255 points
Part Number: DP83TC811S-Q1

Dear team,

My customer recently test the PHY device. When they do the BCI test, there is a fault. The injection current is 100mA. The test frequency range is 1MHz to 100MHz. The frequency increases from 1MHz, and when it is increased to between 25M-30M, the communication between two PHY device is interrupted. At this time the log shows PHY error.  Could you please help solve the problem?

The test circumstance is as below,

Thanks & Best Regards,

Sherry

  • 0
    TI__Mastermind 23675 points

    Hi Sherry,

    Please share with us the schematic and layout around the PHY region.

    Also, please send a photo of the cable used and its connection to both the DUT and LP.

    When there is issue found, what is the issue?

    Please describe in more detail what the issue is.

  • 0 in reply to Ross Pimentel
    TI__Genius 10255 points

    Hi Ross,

    I have sent the schematic and layout to your email.

    In addition, I still have a question. In the schematic, we recommend below circuit.

    1. If the noise inject into TR+,TR+ pin, and the noise will go into the circuit through the DGND pin(the noise can go from GND pin to DGND pin through the resistor), at this time the common mode inductor is bypassed. So could we move the yellow block between red block and green block? In this way, the noise will be filtered out by the common mode inductor.

    2. The green block includes four components: R602, R603, R604 and C603. Could you please tell me what each device does? In this way I can know how to modify them when the test failed.

    3. The blue block includes eight components: C622, C623, R617,L602. Could you please tell me what each device does? In this way I can know how to modify them when the test failed.

    Thanks & Best Regards,

    Sherry

  • 0 in reply to Sherry Liang
    TI__Mastermind 23675 points

    Hi Sherry,

    Can you try re-testing with short between DGND and GND please?

    For our BCI testing, these are typically shorted together and improves BCI results. 

    The green block of CM termination is as per the OPEN Alliance System requirements.

    Those component values are meant to improve the CM emissions and immunity.

    You could try other values but you would violate the system requirements of OPEN Alliance TC8.

    The same is true for moving the CMC. Its placement is in the correct position and if you move it you would violate TC8.

    When issue is observed, is it link drop, bit errors, link drop plus bit errors?

    Is the load box an 811? If it is not an 811, have you tested two of your load boxes together to see if the issue is with the load box?