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TPS22919: Question about smart ON pin pull-down function

Chase Jeong
Mastermind 7505 points
Part Number: TPS22919

Hello TI experts,

my customer considers TPS22919 for their new product, and we have one question about smart ON pin pull-down function.

I understand that this function is working after power is first applied to IN pin.

but how about before power is firstly applied? can ON pin maintain low state until power is first applied?

anyway it is important that OUT pin should maintain low state in our situation. actually the state of ON pin is not important if OUT is low.

please check this issue. Thanks.

Best regards,

Chase

  • 0
    TI__Mastermind 32650 points

    Hi Chase,

    When VIN is unpowered, the device is unpowered. The smart pull down therefore is not powered and the ON pin is floating. Once the device is powered, the the smart pull down will hold the input low until the voltage on the ON pin is puled higher than V_IH.

    Thanks,

    Shreyas

  • 0 in reply to Shreyas Dmello
    Mastermind 7505 points

    Hi Shreyas,

    Thank you for your reply.

    I understand about the state which the device is unpowered.

    think about this, the device is unpowered, and there is no input and output in TPS22919.

    and OUT pin would be low in unpowered state, same as no output.

    please check my thinking is right or wrong. Thanks.

    Best regards,

    Chase

  • 0 in reply to Chase Jeong
    TI__Mastermind 32650 points

    Hi Chase,

    If the device is unpowered in an ideal system and VOUT is discharged then VOUT will remain low. But there is no guarantee that there could not be any coupling or latent voltage from previous use. 

    The device is floating and unpowered.

    Thanks,

    Shreyas