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DRV8825 Charge pump not running

Steve Green
Intellectual 430 points
Other Parts Discussed in Thread: DRV8825

Hi,

I have a prototype board with 2 drv8825 channels. One works fine, the other has 3.3 Vref out but the .01uf charge pump osc cap (pins 1 - 2) is setting at ground (not oscillating). I checked the Vf from the pins to ground with a diode tester (power off of course) and have a value of ~ 1.5v on pin1 of the functioning chip, but open on the other. Just want to verify that the chip is bad before I try to replace it.

 

Thanks,

 

Steve

  • 0
    TI__Mastermind 26065 points

    Hi Steve

    You can test the VCP voltage when power on and the nSLEEP is setting to HIGH. The voltage should be VM + ~(10~13V). If nSLEEP is set to HIGH but the the VCP is just VM or lower. The charge pump circuit may be damaged.

    If you have board working fine, I think there maybe soldering or misconnecting problem of your faults board. Please check carefully when replacing the new one.

    Thanks.

    Wilson

    Motor Application Team

  • 0 in reply to Wilson Zuo
    Intellectual 430 points

    Hi Wilson,

     

    I had checked VCP, it was same as VM. Since I have Vref (3.3) I know sleep is high. Guess I need to try and replace chip.

     

    Steve