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TPS562219A: Brown out time lag

T Kishi
Genius 4425 points
Part Number: TPS562219A

Hi

My Customer has question.

I propose TPS 562219 A to 11 Devices, but it is a very big problem.

There is a possibility of all Lost, Please cooperate us.

TPS562219A.pdf
Q1.How long is the max delay from "Brown out" to restart?

Q2.Is this delay time dependent on output voltage and output current?

Q3.Is there a way to shorten this delay time?

Customer is in a very hurry.
We'd like you to respond immediately.

Best Regard

T Kishi

  • 0
    TI__Expert 5745 points
    What's the brown time mean? Would you mind to zoom it ?
    Does it means the delay time between the Vout drop point and the PGOOD drop point?
  • 0
    TI__Mastermind 34065 points
    Hi

    what do you mean " brown out'? can you make it more clear?
  • 0 in reply to Andy Chen
    Genius 4425 points
    Sorry for the unclear waveform.
    The meaning of "Brown out" is the time the input voltage is dropping below UVLO.
    Waveform assuming "instantaneous power failure"

    At the time of "instantaneous power failure", although the input voltage is over UVLO,
    There is a delay time of about 19ms before the output voltage rises.
    This delay time is a problem.
  • 0 in reply to T Kishi
    TI__Expert 4875 points
    Hi,

    We did not check this kind of quick power off behavior on TPS562219A before. But I think I got some clue here for you.

    First of all, do you think that the Vin during power off goes lower to UVLO threshold? The lowest UVLO for TPS562219A could be lower than 3V. In your waveform, I could not tell whether it is lower than 3V. It also applies to EN. Considering the accuracy of your channel, it is questionable that Vin actually goes to UVLO.

    Secondly, why only output 5V has this issue. It is because that with input goes down, input voltage could be close or lower than 5V. The device will work under max duty and the output voltage will out of regulation. There is no way that output voltage will stay at 5V and output voltage will drop to below UVP threshold. The UVP protection will work and device will enter into hiccup mode. It is what you describe as delay time. For output of 3.3V and 1V, the device will not need to work with max duty and output voltage could still be regulated. UVP will not triggered and delay time is not observed. Thanks!