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DRV8800 fault pin always low

Rodney K Whitehouse
Prodigy 200 points
Other Parts Discussed in Thread: DRV8800

Hello,

I am trying to prototype a system using a DRV8800, but I can't get it to work, the fault pin is always low. How do I find out what the problem is?

I followed the schematic in the data sheet.

VBB  = 12v

VREG = 6.5v - seems low, according to the data sheet.

VCP = 22.3v

nFault & nSleep are pulled up to 3.3v via 3.5k resistors.

The other control inputs are 3.3v also.

I've double-checked my connections, had someone else check them. I've tried it with no load, tiny load (leds) and a motor. Never any output, fault always low. It doesn't seem to matter what the state of the control inputs are.

Does anybody have any idea what the problem might be?

  • 0
    TI__Expert 7455 points

    Hi Rodney,

    Thanks for providing all this information. Is there an schematic you can share with us? If so, feel free to send it to my email at jquinones@ti.com.

    Any thing I can think at the moment is whether there is a short at any of the outputs with another output, VM or GND. The Charge Pump looks like it is working, so clearly the device is coming out of SLEEP mode.

    Can you also check to see if the outputs follow the input logic?

    Will be glad to help you solve this problem. Best regards,

    Jose Quinones

  • 0 in reply to Jose Quinones
    Prodigy 200 points

    It was the Sense line. To me, the data sheet seems to imply that the the Sense line is optional. Now the motors turns.

    However, nFault is still low. Any idea why?