FAULT always LOW

user4664404

Part Number: DRV8432

Hello,

Im trying to use DRV8432 as voltage inverter in paralell full-bridge mode (schema below).

When I apply 60kHz PWM at PWM_A or PWM_B the FAULT output is low. (GVDD is 12V and PVDD 20V) The output was mostly random noise.

Is some special startup sequence required (datasheet says it doesn´t)?

Thank you, Ondra.

over 8 years ago

0 Rick Duncan over 8 years ago

TI__Guru** 114905 points

Hi Ondra,

Before applying the 60kHz PWM, what is the state of the /FAULT pin?

Do you have a heatsink on the device?

Have you checked the OTW pin?

What is the voltage on VREG, GVDD_IN, and GVDD?

Is the GVDD regulator capable of meeting section 8.2.1.2.2 of the datasheet?

0 user4664404 over 8 years ago in reply to Rick Duncan

Prodigy 90 points

Hello,

The /FAULT pin is LOW always, even before applying PWM.

Heatsink wasn't connected to the thermal pad, but the outputs weren't loaded.

OTW pin was HIGH all the time.

VREG voltage in 3.3V, all GVDD inputs 12V.

The GVDD regulator shoul be fine with the datasheet requirements.

What is disturbing me is that with both PWM_AB and _CD at GND, the voltage at outputs OUT_A, B and D was 10.6V with no PVDD connected. The OUT_C was 0V.

I think the device might be damaged.

Regards, Ondra.

0 user4664404 over 8 years ago in reply to user4664404

Prodigy 90 points

I checked GVDD again and found a bad wiring. Thanks for your tips.

Problem solved!

0 Rick Duncan over 8 years ago in reply to user4664404

TI__Guru** 114905 points

Hi Ondra,

We are glad to hear you problem is solved.

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FAULT always LOW