DRV8873-Q1: H-Bridge is used to drive a 12V-5A coil, cycles on and off.

Tim,

"Then when turned off, shorting across the coil to stop the current quickly."

The motor stops quick when short across the coil. But, the coil current would take a long time to get down zero.

"one worked fine, next ones cycle on and off, sometimes "

Does they have the same layout? Can you share the layout?

Regards,

Wang

Tim,

Can you get a scope capture of the nFAULT pin?

Regards,

Ryan

Ryan,

Our engineer thinks its the die temperature getting too hot, which cannot be set via programming? I will try and do an N-Fault pin plot.

Ticket Form for Case - Customer Support (service-now.com)

Some files at this site for examination.

Tim,

After I clicked the link, I saw "Requested record not found".

Would you upload those files or pictures to this thread or update the link?

Regards,

Wang Li

The coil we are using is a 6A coil, H-Bridge says good for 10A, notice 4A coil works fine.

Tim,

What is on the load? What is the inductance?

Does the orange channel show the nFault signal?

It is an electro-magnetic clutch, a round coil with and armature plate. The 4A coil is 7.4mH, the 6A coil is 10.5 mH. The Orange is the nFault signal. Search Results | Literature Portal (altraliterature.com) There are a variety of clutch and brake coils, the application is a lawn mower clutch.

Tim,

OCP retry time is about 4ms. If we can confirm the 4ms, it could be an OCP event.

Regards,

Wang Li

The retry time of this event is 2.3 seconds. It happens when the current reaches about 4.5 amps.

The retry time in the waveform is much shorter than 2.3s. If zoom in the zero current period, we can read it out.

.39 Seconds, does that look right?

In the latest waveform, 0.076s is the retry time. If it is 4ms repeatedly, I would think it is the OCP protection. If it is 76ms, I agree with you. It could be the thermal protection.