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TPSI3052-Q1: Problem with 2-wire and 3-wire recognition

David Dudley
Expert 1280 points

Part Number: TPSI3052-Q1

Tool/software:

I seem to have an issue where I have the device wired for 3-wire operation, however whenever the EN signal goes low, the voltage on the VDDH line goes low.  It seems the device thinks it's in 2-wire mode, however VDDP and VSSP directly connects to the internal power and ground planes on the card.

Ideas on what to look for?

David

  • 0
    TI__Intellectual 1530 points

    Hello David,

    Thank you for reaching out with this TPSI3052-Q1 question relating to 2-wire vs 3-wire mode operation. It may very well be that the device is inadvertently entering 2-wire.

    May you please confirm if you have followed the following best practice in the datasheet (8.3.8 Power Supply and EN Sequencing):

    Essentially, ensuring that Ven is low (less than VIL_EN) until VDDP reaches VDDP_UV_R is the best practice to ensure that the device correctly enters 3-wire mode.

    Otherwise, the behavior you described with your current setup is the expected behavior for 2-wire mode:

    Thank you.

    -Hussain

  • 0 in reply to Hussain Alsahhaf
    Expert 1280 points

    Turns out, this was a mis-communication between the designer and the reviewer.  It was designed correctly, works correctly, is completely correct.  The reviewer didn't seem to realize that you can't just measure a isolated differential voltage using 2 scope probes referenced to the VSSP side of the circuit.

    All is well.

    David