DRV8840: The State of nFAULT while nRESET is Low

Hi Shinichi,

Shinichi Inoue said:

• What is the state of nFAULT while nRESET is low?

The nFAULT and nRESET pins are independent. nFAULT will ONLY go down when a fault is detected by the driver. Section 7.3.6 of datasheet explains the nFAULT response to various fault conditions. 

Shinichi Inoue said:

Is it in a high impedance state?

nFAULT is open drain pin so it will be high-z when logic is reset but will be equal to external pull-up voltage supply when in high-z state.

Shinichi Inoue said:

• If the error condition persists after the DRV8840 is reset, will nFAULT go low again?

Read through section 7.3.6 to learn about the nFAULT response to various faults. Some faults will latch, meaning a reset is required to clear fault, and other faults will retry, meaning outputs are re-enabled after some time but nFAULT will go LOW again if fault persists.

Regards,

Pablo Armet