DRV8251: Questions about fault

Hakjin Jeong said:

Q1) There seems to be three system faults(OCP, TSD, UVLO). if one of them occurs, how can  MCU know the occurrence of this fault(Motor stop by fault)? Can you recommend a topology to do that?

The DRV8251 does not have a fault indicator pin.  You would have to measure the output current or voltage with the MCU and see if it unexpectedly dropped to 0.  Any driver with a nFAULT pin would work, such as the DRV8872

Hakjin Jeong said:

Q2) Let's assume that  ITRIP(current regulation) is set to lower value than IOCP. if a short across the motor winding occurs, Is the current still regulated at ITRIP? or does the OCP fault occur?

The driver will try its best to regulate the current to ITRIP but in the case of hard short the current will rise much faster than the driver is able to regulate the current. When this occurs, the driver will trigger an OCP fault.

Hakjin Jeong said:

Q3) What is the exact condition of VOCP_ISEN additional protection? Is this fully independent with OCP or current regulation?

VOCP_ISEN is the overcurrent protection trip point on the ISEN pin. It is independent with OCP and current regulation. This provides additional protection when the VM voltage is low or the RSENSE resistance on the ISEN pin is high.  You can read more about it in 8.4.3.1 Overcurrent Protection (OCP).

Regards, 

Jacob