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DRV8814 driver fault condition

Garcia Carrillo
Prodigy 10 points
Other Parts Discussed in Thread: DRV8814

Hi,

I have a question about DRV8814 driver:

I´m using a 24V 0.9A dc motor with a start current of aprox. 4-5A  and I´m having several problems starting motor because fault conditions set continuosly. I have read  datasheet and other tech documents that tell about current control of the driver using a internal PWM control loop for avoid problems with start currents in DC motor.
I set the xVref to limit Ichop  value of aprox 2.5A but I only get fault condition. If set the xI0:xI1 in way to decrease motor current, it´s worst...
Really driver control motor current ?, I think the only driver makes is to set the fault condition in function of xVref threshold voltage.
 What´s the problem ?, Why driver no litmis motor current?

I hope your answer
Thanks in advance.

A. Garcia
I+D Engineer
  

  • 0
    TI__Mastermind 20985 points

    Hello, hopefully we can come up with a solution.

    I think you have already identified and understand the problem, with nFAULT triggering.  The DRV8814 OCP may trip as low as 3A, whereas your startup current is 4-5A.  As datasheet Page 10 states, the OCP functionality is independent of Ichop/VREF.

    What's your motor's internal resistance?  Can you try adding a series inductor to the motor?

    Best regards,
    RE