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DRV8800PWPR nFAULT problem

Justin Erfan
Expert 3385 points
Other Parts Discussed in Thread: DRV8800

Hello,

I am trying to use the TI Motor Driver DRV8800PWPR to drive transport motor (running at 12V).

The problem is that on some devices, while under normal load, it generates an nFAULT signal which is considered a failure by the CPU.

I did some experiments to cut the trace for nFAULT and confirmed that  the unit is still working. What could be wrong and how can I fix the issue?

  • 0
    TI__Mastermind 26065 points

    Hi Justin

    In DRV8800, nFAULT reporting does not affect any device operation. So you could get the nFAULT while the device is still running normally. But there must be some warning conditions happened, such as over current, under voltage or over temperature.

    To determind which case alerts the fault singal, we can monitor the related current, voltage or temperature. Most likely it could be a temporary over current event during motor start, stall, or reverse. In your case, UVLO could also be possible since you have 12V VM. If you don't have big enough bulk caps closing enough to VBB pin or the power supply is weak, the voltage seen from VBB may drop below UVLO when motor current is at the starting or stall peak level.

     Best regards,

  • 0 in reply to Wilson Zuo
    TI__Expert 3385 points

    Thanks Wilson!

    This definitely gives a good start  to determine which fault condition triggered nFAULT. I will see what's going on.