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DRV8837: Flyback current handling in DRV8837

Part Number: DRV8837

I've incorporated a DRV8837 into my motor application.  VM is supplied by a boost regulator that maintains an output of 7V.

When I drive the motor and then abruptly brake, I see the expected negative flyback current coming from the motor.  I would also expect to see that same flyback current driven back to the boost output from the DRV8837 as well, but I do not.  I only ever see positive current into the DRV8837.

What's going on under the hood here?

  • Daniel,

    The current going back to the boost output or not is depended on the boost converter design. For example: if the high side switch of the boost converter is a diode, the boost converter output current cannot go back.

    BTW, if the negative flyback current is coming from the motor and no current back to boost output, you are going to see the DRV8837 input voltage is pushed to high which could be higher than the boost converter regulation point.