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UCC2897A: Deglitch time for UVLO comparator?

Allen Wachter
Expert 6730 points
Part Number: UCC2897A

Customer is seeing a small ringing in the 1-2ns range on the VDD pin input down to 8.77V.  While this is still above the UVLO max level the question came up if there is a minimum pulse width to trigger the ULVO comparator.  Can you comment on this please?

Thanks! 

  • 0
    TI__Mastermind 34465 points

    Hi Allen,

    It is very difficult to reliable and accurately measure a 1nS pulse within a switching power supply.
    The pulse observed on the scope may be due to noise pickup on the scope probe and may just be radiated noise picked up on the ground lead of the probe.
    The probe needs to be directly connected from the VDD pin to GND using high frequency measurement techniques.

    I think that if you are seeing any noise on the VDD pin then the decoupling on VDD is too far away or too small a value.
    That really would be an issue.
    VDD should be a stable DC value with very little ringing.
    You would normally operate with a VDD value of 12V to 15V  which is well above the UVLO value of 8V.

    Regards

    John