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DP83869HM: DP83869HM: Connect directly to Intel i210 without transformers?

Wesley Clow
Prodigy 110 points
Part Number: DP83869HM

May I directly connect the DP83869HM to the Intel i210 without transformers? This is an embedded system, so the connection is not exposed and is contained on a single board. 

  • 0
    TI__Mastermind 18425 points

    Hi Wesley,

    Direct electrical connection between Ethernet PHYs is not recommended. There needs to be some sort of isolation. Transformer based isolation is most common method. You can also try using capacitive isolation by adding AC coupling capacitors on the MDI lines going from one PHY to another, but you will need to perform system level testing to make sure that it is working well in your application.

    -Regards

    Aniruddha

  • 0 in reply to Aniruddha Khadye
    Prodigy 110 points

    1. Is the DP83869HM a current or voltage mode PHY?  We've reviewed AN-1519 for the 10/100 PHYTER PHYs and are wondering if the DP83869HM would require biasing in a transformerless, capacitor-coupled application.
    2. Can a single transformer be used instead of a single cap or dual transformer to provide the required isolation?

  • 0 in reply to Wesley Clow
    TI__Mastermind 18425 points

    Hi Wesley,

    DP838669HM has voltage mode line drivers. You do not need to connect biasing resistors on the MDI pins.

    Dual transformer connection is what we have characterized since that is the most common use case. However, single transformer/capacitor can also work but I will recommend you to run your own system level test to ensure proper operation.

    -Regards

    Aniruddha