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TPS7A91: Reverse current and discharge circuit

Ryotaro Fukui
Intellectual 2345 points
Part Number: TPS7A91

Hello team,

I received a question about reverse current of TPS7A91. I would appreciate if you could give us some advice.

Some LDOs recommend a discharge circuit outside the device between VOUT and VIN in consideration of when VIN <VOUT.
Regarding "TPS7A9101DSKR", there was a description about discharge circuit in the data sheet, but it is okay to think that the reverse current does not occur because the current flows through the discharge circuit when the input power is down?

Best Regard,
Ryotaro Fukui

  • +1
    TI__Expert 6825 points

    Hi Fukui-san,

    If you are referring to the active discharge circuit internal to the LDO this will not discharge the output once the device has dropped below a certain input voltage. Because it is an NMOS device that is discharging the output you have to have enough headroom to turn that on. 

    If you have large output capacitors in your system and you are expecting large changes on the input voltage then I would recommend adding a Schottky diode from the output to the input to discharge in the event of reverse current. 

    Regards,
    Mark