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TPS7B7701-Q1: TPS7B7701-Q1 EN toggle with short to battery/GND conditions

Piotr F.
Intellectual 2510 points
Part Number: TPS7B7701-Q1

Hello TI Team,

Is there any limitation in toggling/asserting EN pin of TPS7B7701-Q1 LDO when its Vout is shorted to battery or GND?

By asserting EN pin every ~5seconds during Vout short to GND/batt customer plans to diagnose if Vout fault is present or removed and avoid LDO overheat same time.

Is there any issue/known limitation with that operation scheme?

Piotr

  • 0
    TI__Mastermind 41085 points

    Hi Piotr,

    If I'm understanding this correctly, the customer wants to disable the part every ~5 seconds? How long will the part be disabled?

    I don't think there are any limitations on enabling/disabling the part. All that will happen if the part is disabled during a short-circuit event is the pass-FET will close and current will stop flowing through the LDO. This is of course assuming that it is never the case that Vout > Vin, which is a different problem. 

    Best regards,

    Nick

  • 0 in reply to Nick Butts
    TI__Intellectual 2510 points

    What happens if Vout > Vin and you disable TPS7B7701-Q1 (or toggle EN pin every 5 seconds)?

    Is below that you refer to?

    So, if there is reverse current flowing for more than 5us (typ) toggling EN pin will not start the LDO until short is removed?

  • 0 in reply to Piotr F.
    TI__Mastermind 41085 points

    Hi Piotr,

    That is correct, if the fault is not removed when EN is toggled then the part will remain off. To turn the part back on the fault must be removed and then EN toggled.

    I think I understand your original question now. It should be fine to toggle EN every ~5 seconds to check if there is a fault present as long as the pulse width is small enough so that the output does not deviate too much when the part thinks it is turning off.

    Best regards,

    Nick