TPS51225CRUKR Voltage limit

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  • Bradbeat
    Member
    • Jul 2025
    • 15
    • Belgium

    #1

    TPS51225CRUKR Voltage limit

    Hi,
    I have a PGOOD pin down on this chip and I’m wondering if it could be because there is 5,2 v on VREG5 ( the high limit according to the datasheet is 5,1v ).
    if yes, why is it to high?
    the motherboard board is LA-G881P.
    thank you.

    here is some measurements :
    • VIN = 16,3 V
    • VREG3 = 3,299 V
    • VREG5 = 5,203 V
    • SW2 (repos) = 3,423 V, pikes at ~16,4 V
    • VBST2 = 8,592 V → VBST2 − SW2 = ≈ 5,17 V
    • VO1 = 5,28 V (stable)
    • EN1 = 3,08 V, EN2 = 3,04 V
    • VFB1/VFB2 ≈ 2,1 V



  • mon2
    Badcaps Legend
    • Dec 2019
    • 14512
    • Canada

    #2
    No. Pgood is open drain so it must feature an external pull up resistor to park the line when the signal is released. When Vout is 95% reached, the line should float.

    Comment

    • Bradbeat
      Member
      • Jul 2025
      • 15
      • Belgium

      #3

      Thank you for your answer,
      I can't see any pull up on the board so I assume it is in the super I/O chip?
      If it is, is the SIO burnt or could it be un SIO firmware issue?

      Comment

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