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TPS7H1101A-SP: PG Pin

Errol Leon6
Expert 5850 points
Part Number: TPS7H1101A-SP

Hello team,

My customer is using the TPS7H1101HKR/EM on a project, and they are planning on pulling up the PG pin to a separate voltage other than VOUT. Can you confirm that PG is always pulled down unless VOUT is above its threshold (roughly 80% according to the datasheet)? 

They are concerned that during startup (before there is any voltage on VIN) that the power-good pin will be in a Hi-Z state allowing the voltage from my pull up to make the power good signal high.

Thank you in advance for your support!
Errol

  • 0
    TI__Guru 62930 points

    Good question.

    I suspect that it will be high impedance up to a point where device is biased sufficiently to function and output appropriate PG status.

    However, I need to research this and get back to you to confirm.

    I will verify and reply back.

    Regards,

    Wade

  • 0 in reply to Wade Vonbergen
    TI__Guru 62930 points

    Errol,

    I was able to confirm that PG is high impedance when device is not powered.

    I ran a test case during power up, and PG gets pullled low when Vin hits about 400mV, then releases when in regulation.

    During power down, PG again gets pulled low and goes high impedance at approximately Vin of 1V and lower.

    Their system will need to insure that PG status is gated with Vin status to insure proper power good indication.

    If this answers your question, please click "This Resolved My Issue"
    Regards,
    Wade