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DP83867CR: DP83867 connection to another PHY Controller

Aaron_Rangel
Intellectual 450 points

Part Number: DP83867CR
Other Parts Discussed in Thread: DP83869

I am writing regarding the thread, "[FAQ] TI Ethernet PHY Capacitive Coupling (Transformerless Operation)."
 
It is mentioned that transformerless operation is not supported for the DP83867. My question is specifically about a scenario where the DP83867 is connected directly to another PHY controller on the same PCB, with no RJ45 connection.
 
In this specific case (PHY-to-PHY on the same board), are transformers still required for the connection? Could ib e possible to connect both of them without transformers? See attached approach. The XXXX PN of the other PHY is not from TI and it is not disclosed, it comes from a SOM (System on Module) mounted in the PCB (same reference GND singal for all the electronics).
 
PHYs_Connection_Approach.png
 
Please, let me know how I should proceed to ensure the proper connection.
Thank you.
 
  • 0
    Intellectual 450 points

    Hello,

    Could you please help on this in order to clarify it? Any feedback on this?

    Thank you all in advance.

    Best regards,

  • 0 in reply to Aaron_Rangel
    TI__Mastermind 23141 points

    Hi Aaron,

    I apologize for the delay. US office was closed for Thanksgiving holiday.

    Even though it is on the same PCB, we recommend not using transformerless option on DP83867 as it is reported to have CRC errors. 

    Would it be possible to use DP83869?

    For pricing, please contact the supported FAE who can inquire about the pricing to the marketing.

    Best,

    J

  • 0 in reply to J
    Intellectual 450 points

    Hello J,

    The DP83869 Ic was the option we were thinking of in case your feedback would suggest not to be used in a transformerless setting.

    I think it is almost pin-to-pin compatible (same package RGZ VQFN, 48) with DP83867 IC, with some minor changes in pinout assignments.

    Anyway, could we have some discussions about this transformerless connection with this DP83869?

    We do have an NDA and would be helpful to receive support on this.

    Best regards,

  • +1 in reply to Aaron_Rangel
    TI__Mastermind 23141 points

    Hi Aaron, 

    Of course. As the FAQ mentions, DP83869 supports transformerless configuration. You can use decoupling capacitors to achieve this as the FAQ mentions. In addition, we recommend to keep the MDI traces within 2000 mils on the PCB. 
    Please let me know if you have any additional questions about this. 
    Best,
    J