DRV8801 Current Sensing

Support Motor controllers/drivers and motors
1

I am using the DRV8801 motor driver carrier board to drive a small 12V motor. I’m powering the motor with a DC power supply set to 12V with current limited to 0.37A (the max continuous current of my motor) and the CS pin is consistently outputting 11V. I’m sending the PWM pin a 5V input with 100% duty cycle, supplying the VDD pin with 5V, and the BRAKE pin is pulled low. Even when pulling the BRAKE pin high, I still get 11V at the CS pin. Measuring the current in the motor directly (using a multimeter) yields 0.030A.

The documentation page says that the CS pin will output a voltage proportional to the current in the motor winding, approximately 0.5V/A. I’m not sure why the measured voltage at the CS pin is so high, and why it isn’t reading 0V when BRAKE is pulled high.

2

Hello.

Can you post some pictures of your board and setup? How are you measuring the voltage on the CS pin?

-Patrick

3

I’m measuring the voltage on the CS pin with a multimeter. The MCU, power supply, and driver board all share a common ground, which is the reference for my measurement.

IMG_20190919_160153166
IMG_20190919_1601531664032×2268 2.17 MB
IMG_20190919_160224745
IMG_20190919_1602247452268×4032 2.31 MB

4

Is everything about the driver working except for the CS pin?

I think we should try to simplify your system as much as possible to find the problem. Could you disconnect everything from the driver except for the motor power connections? Can you also connect directly to the board’s headers instead of going through the breadboard? What is the voltage on the CS pin in this setup? If you change the motor power supply voltage, does the voltage on the CS pin change?

-Patrick