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TPS22917: External pull-down for ON pin?

Will DeCook
Prodigy 240 points
Part Number: TPS22917

Hi,

The TPS22917 datasheet says that the ON pin has an internal Smart Pull Down that pulls the ON pin down when it is not driven, negating the need for an external pull-down. The Pin Functions table in the same datasheet also states to not leave this pin floating.

Which is it?

Referencing TPS22917 datasheet - SLVSDW8A –SEPTEMBER 2017–REVISED FEBRUARY 2018

Thanks,
Will

  • 0
    TI__Genius 10855 points
    Hi Will,

    Thanks for reaching out on E2E!

    The Smart pull-down prevents the EN/ON pin from floating or entering an undetermined state once the voltage on the pin is brought below VIL. If you can ensure that the voltage on the pin is brought below VIL when disabled, then the internal pull-down will pull the pin to 0V.

    Thanks,
    Arthur Huang
  • 0 in reply to Alpha H
    Prodigy 240 points
    So it sounds like I need an external pull-down to help the internal pull-down.
  • 0 in reply to Will DeCook
    TI__Genius 10855 points
    Hi Will,

    Are you hotplugging or disconnecting the EN/ON pin such that the input remains floating? If so, then you would need to include an external pull-down. Otherwise, if the voltage can fall below VIL, you should be ok.

    Thanks,
    Arthur
  • 0 in reply to Alpha H
    Prodigy 240 points
    The ON pin will remain connected to a controlling FPGA, which will be powered up before the TPS22917. But during initial setup and testing, this pin may not be driven low by the FPGA prior to the TPS22917 receiving power, in which case I want to ensure the ON pin is pulled down.