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DRV8801-Q1: Vbb disconnect during operation

Kevin Schmidgall
Expert 3870 points
Part Number: DRV8801-Q1

Hi!

I guess this is more of a general motor question but the DRV8801-Q1 is being used so I wanted to check my reasoning...Vbb is coming from a load switch. That load switch may be subject to undervoltage pulses that would shut off the load switch during operation. My question is what would happen if the DRV8801-Q1 is running and then Vbb is disconnected because the load switch goes to undervoltage condition? My answer is the motor would shut off because the H-bridge isn't being driven anymore but is there a time where the the undervoltage pulse is short enough for the motor to not even notice that the Vbb disconnected?

Regards,

Kevin

  • 0
    TI__Genius 14487 points
    Hi Kevin,

    I hope everything is going well :-)

    Your reasoning is correct. The spinning rotor has inertia, so the motor won't not stop immediately when it is no longer powered. During this power-off condition, the current in the winding inductance will discharge through the body diodes of the FETs in the H-bridge and through the body diode of the load switch FET into the supply.