DRV 8842 nFault Pin

Igor Cerdic

Other Parts Discussed in Thread: DRV8842

Hi,

I designed a circuit with a DRV8842 and I am measuring always ~1.8V at the microcontroller in the MOTOR1FAULT Pin, no matter if the driver is in fault or not.

Can you please tell me what I did wrong?

[edit] Seems like image upload is not working, here is a link: [/edit]

Thank you very much!!!

over 7 years ago

0 Rick Duncan over 7 years ago

TI__Guru** 114905 points

Hi Igor,

Are you using the nSLEEP pin? When the device is in sleep mode, V3P3OUT is disabled so there is no pullup.

Have you looked at nFAULT with a scope? What is required to re-enable the DRV8842? Please refer to section 7.3.6 to help determine the cause of the fault.

0 Igor Cerdic over 7 years ago in reply to Rick Duncan

Intellectual 360 points

Hi Rick,

I am using the nSleep pin, but the driver is defently not sleeping.
I have not looked at the pin with a scope, I can try if it helps to debug.
If I reset the board, it works again. But absolutely no change reading the voltage of the MOTOR1FAULT signal with my µc, so I think it is an overcurrent fault.

Thank you very much!

0 Rick Duncan over 7 years ago in reply to Igor Cerdic

TI__Guru** 114905 points

Hi Igor,

Your description sounds like a overcurrent fault. It is puzzling why the nFAULT is at 1.8V though.
Using the scope to determine if nFAULT is toggling is always helpful.

Is it possible the GPIO is set to an output by accident?

0 Igor Cerdic over 7 years ago in reply to Rick Duncan

Intellectual 360 points

Hi, Rick. Thank you for you reply. I damaged a chip, so I am not able to measure with a scope at the moment. I'll come back to this when I repaired the situation. Thank you!

0 Igor Cerdic over 7 years ago in reply to Igor Cerdic

Intellectual 360 points

And defently the pin is not set as output :)

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DRV 8842 nFault Pin