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DP83TC812S-Q1: TRD pin connection method

Link Huang
Expert 7225 points
Part Number: DP83TC812S-Q1


Hi Team，

My customer is KOSTAL, they used DP83TC812S-Q1 on JMC's ZCU project.

Since 100M PHY is a reserved function in this project, DP83TC812S-Q1 may not be used on some models. Therefore, in their design, they plan to use “contact pin” to expand the TRD_P and TRD_N pins. The picture of the "contact pin" is as follows:

Will using this kind of contact pin affect the performance of the device?

BR，

Link

  • 0
    TI__Genius 14006 points

    Hi Link,

    Do TRD_P and TRD_N each expand to a single pin in your photo? Or is it all the pins?

    Are they going to be connected directly to another board to another PHY or are they just test points? Why are they using this configuration?

    If I understand your photo correctly, I would not recommend this kind of configuration. The pins could introduce impedance mismatches and the differential impedance of the TRD_P/N pair should remain 100ohms +/-5%.

    Best regards,

    Melissa

  • 0 in reply to Melissa Chang
    TI__Expert 7225 points

    Hi Melissa,

    Thanks for your reply.

    KOSTAL engineers thinks that the most common connection method of 100M-T1 Ethernet is similar to the figure below：

    Currently, we are considering using press-pin connectors, which are essentially the same as the connector in the picture above, except that the process of fixing the connector to the PCB is different.

    There is no essential difference between the two connectors in terms of electrical connection. What are the main influencing factors on Ethernet communication? Why could the first type of connector work but not the second type of connector?

    BR，

    Link

  • 0 in reply to Link Huang
    TI__Genius 14006 points

    Hi Link,

    The Automotive Ethernet BroadR-Reach connector shown on the left has been tested extensively for signal integity, s-parameter and load capacitance requirements for Open Alliance.

    The connectors the customer is using may not have the correct s-parameter or load capacitance requirements so we would not recommend using them.

    I hope this helps.

    Best regards,

    Melissa