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DC bias circuit on DP83867

Ken Hashi
Intellectual 790 points
Other Parts Discussed in Thread: DP83865

Hello.

In Ether phy, DC bias may take the line to a pulse transformer.

With the DP83865 data sheet, an external DC bias circuit is added.

Will the external DC bias circuit be unnecessary for the lines from TD_P/M_x terminal of DP83867 to a pulse transformer?
In DP83867, does the DC bias circuit have it built-in?

Regards.

k-hashi.

  • 0
    TI__Mastermind 31600 points
    When you refer to the external DC bias circuit of the DP83865, I believe you are referring to the voltage connection to the transformer center taps and the 50 Ohm resistors on the TD_P/M_x traces, correct? These are required due to the DP83865 line driver architecture. The DP83865 has a current mode line driver which requires a DC connection to the transformer center taps.

    The DP83867 line driver has a different architecture. The DP83867 has a voltage mode line driver so no DC connection to the transformer center taps is required. The DP83867 includes integrated termination resistors so no external 50 Ohm resistors are needed on the TD_P/M_x traces.

    Patrick
  • 0 in reply to Patrick OFarrell
    Intellectual 790 points

    Hi Patrick-san

    Thank you for your explain.

    I can understand meaning of DP83867 line driver.

    Thank you very much.

    Regards.

    k-hashi.