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A question for Bob Smith

Other Parts Discussed in Thread: TPS23861

Hi team,

A customer sees the following sentence (red line)  in an app note (slva531a: TLK1XX Design and Layout Guide). PoE applications have the Bob Smith termination, doesn't it? Can you explain what this means?

 

Thanks,

Sam Lee

  • Hi Sam,

    You cannot use bob smith termination because you are not terminating the cable facing side of the center tap.
    The energy is transferred from the PSE to the PD using the cable and center tap.

    Kind regards,
    Ross
  • Hi Ross,

    Thank you for your reply. I'm sorry I didn't understand your explanation exactly.

    For example, below pictures are the schecmatics of PSE and PD application. I see the bob smith termination, is that right? Can you give a little more explanation?

    -. PSE application (in TPS23861 EVM)

    -. PD application (in TPS2375A EVM)

    Thanks,

    Sam Lee