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TPS54328: Question about output discharge function

Go
Genius 4220 points
Part Number: TPS54328


Hi, 

Does the TPS54328 discharge output caps actively when EN goes Low or VIN reaches down to UVLO threshold?

If yes, how does TPS54328 do it? (Low-side FET turns off? or any other discharge circuit exist?)

Thanks,

Go

  • 0
    TI__Guru**** 191445 points
    I am pretty certain that TPS54328 does not have any active pull down or discharge for Vout
  • 0 in reply to JohnTucker
    Genius 4220 points
    Hi, John-san,

    Thank you for your comment,

    If we want to decrease Vout during shutdown faster,

    Is it possible to use one-tenth the value of the recommended Vout setting resistor?

    Thanks,

    Go
  • 0 in reply to Go
    TI__Guru**** 191445 points
    I have not supported TPS54328 for a couple years now. But using one tenth value will result in 2.21 kohm for the bottom resistor and and some other value in the kohm range for the top resistor, depending on the output voltage. I have used values that low for many other similar converters. I do not see any issue at all for that.
  • 0
    TI__Expert 4875 points

    Hi Go,

    To double check, you could apply a voltage like 2V on SW pin and GND and measure the current. If there is several mA curernt, subtract the current thru fb resitor, it is the discharge circuit current. You could calculate the resistance of the discharge circuit in this way. 

    Best,

    Anthony