DRV10970: Issue with DRV10970PWPR – Motor Jerking and No PWM on W Phase Output

Tool/software:

Dear TI Support Team,

I am using DRV10970PWPR to drive a sensorless BLDC motor, but I am facing an issue during startup. The motor only jerks and does not start rotating. Upon checking with an oscilloscope, I observe PWM signals on U and V outputs, but there is no PWM on the W-phase output (Pin 11).

Here are the details of my setup:

• IC: DRV10970PWPR

• Motor: Sensorless BLDC

• Supply Voltage: [12V DC]

• PWM Control Input: Arduino Nano

Observed behavior:

• Motor only makes small jerks and does not enter closed-loop commutation.

• U and V phases show PWM output, but W phase remains inactive.

Questions:

1. Is this normal behavior during open-loop startup, or does it indicate a configuration/hardware issue?

2. What could prevent the DRV10970 from energizing the W phase?

I have referred to the datasheet, but I would appreciate your guidance or any troubleshooting steps.

Regards,

Gowthaman