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DS25BR100 Repeaters

Anand Kumar Rai
Intellectual 720 points
Other Parts Discussed in Thread: DS25BR100

Hi all!!!

I have 10base T ethernet TX+/TX- and RX+/RX- from MAC that need to be connected a back plane connector(not RJ-45 connector) on my the board through magnetics.

Do I need to use DS25BR100 repeaters between MAC and back-plane connectors. Basically I want to know, how much length 10base T signals can travel on PCB(FR-4), so that they be detected without much loss.

Thanks in advance

Best Regards

-Anand 

  • 0
    TI__Expert 5175 points

    Greetings -

    This is difficult to advise on, as it depends on the IO cell in the MAC and PHY (unnamed) on what they can drive.  Best is to see if there is any guidance on the MAC drivers for length, and also see what the downstream device needs in terms of swing (threshold).  Then insert a BUFFER if needed.

    Typically the MAC and PHYs can be 5 to 10 inches apart without buffers.  Key is tp make sure the lines are all matched length to perserve CLOCK to Data relationship.

    Best Regards

    John Goldie

  • 0 in reply to John Goldie
    Intellectual 720 points

    Hi John,

    Thanks for your feedback!!!

    MAC used is a Freescale powerpc MPC8387 and PHY used is Broadcom BCM5461S. And we are definitely taking care of matched lines with minimum number if vias between MAC and PHY. Shall I think like if we maintain less than 5 to 10 inches distance between MAC and PHY, then repeaters are not required??

    Best Regards

    -Anand

  • 0 in reply to Anand Kumar Rai
    TI__Expert 5175 points

    Greetings -

    I cant comment on the capability of another vendors parts, but typically we see direct connections of 5 to 10 inches between MAC and PHYs, likely to be fine.

    John

  • 0 in reply to John Goldie
    Intellectual 720 points

    Hi John,

    Thanks for your feedback and support, we will take care of your suggestions.

      Thanks and regards

    -Anand