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DRV8871: Help identify problem with DRV8871

Hau Tran
Intellectual 615 points
Part Number: DRV8871

Hello all,

I am trying to control a 24V DC motor using DRV8871 breakout board from Adafruit . I got into this situation I can't quite explain.

The motor runs fine if I hook it up directly to 24V Power Supply. I am using 24V/2.5A MeanWell Power Supply. .

However, when I control the motor through the breakout board, the output voltage is only about 5V. The PWM frequency I used to control the motor is 60HZ at 75% Duty Cycle. I tried to change the resistor to a lower value in order to allow more current pass through if needed, it doesn't change the situation. I also monitor the current pull by the motor, it drew around 0.5 A no load and around 1 A with load, that means the Power supply has plenty of current to run the motor, I believe. 

Please help me explain this situation, if possible, do you have any idea how to fix it?

Thanks,
Alex

  • 0
    TI__Guru** 114905 points
    Hi Alex,

    It is possible one of the protection circuits of the DRV8871 is being activated.

    Please examine the outputs with a scope.

    If you observe the outputs disabling for approximately 3ms and then re-enabling, this is an indication of an overcurrent event.

    If you observe the outputs disabling for much longer than 3ms , this is an indication of an overtemperature event.