DRV8312: The three phase outputs of the drive chip are different and the output voltage of out_B is insufficient

Hi Team,

GVDD_X is supplied at 12 V and PVDD_X is supplied at 28 V.

Issue1: output voltage of out_a/C is 12 V and output voltage of out_B is 28 V without PWM input, that is, three-phase output values are not symmetrical.

Issue 2: with 20-kHz, 0.5 duty cycle triple PWM inputs, the out_a output waveform is a normal 28-V duty cycle 0.5 PWM waveform, while the out_B waveform has the correct duty cycle. The voltage cannot reach the maximum value as shown in the following figure:

The customer has tried with the following but there are no effects:

1) Replace bootstrap capacitor of BST_B.

2) Increase PWM frequency to 40 kHz.

Could you help check this case? Thanks.

Best Regards,

Cherry