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DRV8844: DRV8844 Fault always on

Izzo Zdadze
Prodigy 10 points
Part Number: DRV8844

Tool/software:

What could be the reason for Fault being always asserted? Schematic below; I'm trying to simply get the part working, not drive anything yet. V3P3OUT does output 3.3V.

  • 0
    TI__Genius 16310 points

    Hi Izzo,

    The nFAULT pin is an open drain output which requires an external pull-up resistor. Typically the resistor value is 10kΩ.

    Is there a pull-up resistor already in the design?

    Best,

    David

  • 0 in reply to David Medis
    Prodigy 10 points

    Hi David,

    There's a 100k pull-up to 3.3V (3.3V is the logic level supply).

    Is there a specific sequence of driving nSLEEP and nRESET high? I have them connected to to 3.3V via pull-ups as well.

  • 0 in reply to Izzo Zdadze
    TI__Genius 16310 points

    Hi Izzo,

    Using a 100kΩ pull-up resistor on these pins is likely to much. What's the voltage when measuring nFAULT? I would suggest trying a smaller pull-up resistor value, maybe 10kΩ or 4.7kΩ.

    Best,

    David

  • 0 in reply to David Medis
    Prodigy 10 points

    Hi David,

    I've tied nRESET and nSLEEP to 3.3V with no pull-up, and used 4.7 kΩ for pulling up nFAULT, and now the part works.

    Thank you for your help.