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UCC27211: drop on HB-HS

Given Ding
Expert 7325 points
Part Number: UCC27211

Hi Team,

As you can see in below waveform, there is Vout drop on HB-HS ( <5.6V/3ns.) measured at HB and HS pins. 

 Datasheet mentioned,  VDD UVLO is 6.2V min.  Will such short drop trigger HB-HS UVLO?  And how much time on drop will trigger UVLO? 

BRs

Given 

  • 0
    TI__Mastermind 20950 points

    Hello Given,

    I looked at the UCC27211 regarding information on expected UVLO delays. The HB UVLO falling delay is much longer than the negative glitch you show in the scope plot. There are UVLO delays to avoid false triggering on noise spikes and short term disturbances. The driver will not go into UVLO with the negative transient shown.

    It is also difficult to measure this voltage accurately since this is a voltage referenced to a switching ground reference, HB to HS. So it is possible that the negative glitch in the scope plot is not as low as measured.

    Confirm if this addresses your questions or you can post additional questions on this thread.

    Regards,

  • 0 in reply to Richard Herring
    TI__Expert 7325 points

    Hi Richard, 

    Thanks. It's clear. 

    As you mentioned, expected UVLO delays is longer, could you please kindly inform me the value of expected UVLO delays? Thanks.

    BRs

    Given 

  • 0 in reply to Given Ding
    TI__Mastermind 20950 points

    Hello Given,

    I recall from simulation data I reviewed, that the falling UVLO delay is in the 1-2us range, which is quite beyond the small glitch in question. This is not a datasheet tested parameter however. Make sure the customer understands this delay is not ATE tested.

    Regards,