DRV8881E / nFAULT

K.Yaita

Hi Team,

I understood nFAULT pin will be driven low when VM pin falls below the undervoltage lockout threshold voltage(6.4V max).
If VM gradually falls continuously less than 6.4V, when does nFault go to Hi-Z?

I believe nFAULT pin will be Hi-Z if VM pin falls low enough to 6.4V.
I assume nFault pin is pull-up to VM pin in this case.

Best Regards,
Yaita

over 9 years ago

0 Rick Duncan over 9 years ago

TI__Guru** 114905 points

Hi Yaita-san,

nFAULT pin should be pulled up to mcu VCC (3.3 or 5V typically).

You are correct. nFAULT will be Hi-Z when VM continues to drop. There is a point the internal logic cannot control the nFAULT output.
We will check the value and provide a typical voltage.

0 K.Yaita over 9 years ago in reply to Rick Duncan

Guru 29720 points

Hi Rick-san,

I understood nFAULT pin should be pulled up to mcu VCC (3.3 or 5V typically) because of ABS max as you said..

It is helpful for my customer if you check the value as a reference.

Best Regards,
Yaita

0 Rick Duncan over 9 years ago in reply to K.Yaita

TI__Guru** 114905 points

Hi Yaita-san,

nFAULT is active to approximately VM=1.8V. This assumes the device is awake (nSLEEP = logic 1) when VM is dropping.

If nSLEEP is a logic 0, nFAULT is not active for any VM voltage.

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DRV8881E / nFAULT