DRV8718-Q1: DRV8718Q1 OCP function consulting

Hi Shuang, 

Thank you for your question. 

Let me explain your question to see if I get it correctly. said: 

1- "When DRV8718 not drive MOS FET" it means that the EN_DRV is set at 0b or DRV_OFF: High which disable the outputs. 

2- "our offline diagnostic not open, " do you mean the EN_OLSC: 0b which disable the Offline diagnostic? if yes, this condition means there is no offline diagnostic. 

3- "if there happen MOS FET short to ground, whether our DRV8718 OCP function will work normal or not?"  if short to GND occur when the outputs are disabled, then there is no voltage on outputs and therefore no current is passing through the FETs and OCP is not triggering. 

To detect short to GND when the MOSFET are not driving, you need to utilize offline diagnostic function and conduct offline short circuit and open load diagnostics of the external power MOSFETs and load.

If the outputs are shorted to GND, the OCP will trigger when you turn ON the MOSFETs. 

Please let me know if you have any questions. 

Best 

Motjaba