DRV8432: DRV8432 driving 2 TEC: Output duty cycle is limited in a very low level

Part Number:DRV8432

Hi TI experts,

We are using DRV8432 to drive 2 TECs seperately, which supports both heating and cooling.  In our design, DRV8432 is set in mode 1(M1=M2=M3=0), dual full bridges with cycle-by-cycle current limit.

At first, it works so fine. Cooling/Heating power is controlled by the duty cycle of PWM input to DRV8432.

But somehow, in one of my board, the duty cylcle of OUT_X is fixed at a very low value (about 10%), no matter how we changed the PWM input duty cycle. And if the duty cycle is zero(PWM_X = low), the OUT_X will be low. This means DRV8432 is working. But the output duty cycle is limited in a very low level.

And the OTW and FAULY are still high, which means device is under normal operation.

Do you have any idear about this?

Thanks.

BR,

Jon