ZHCSDA7G July 2014 – February 2018 DRV10983
Lock4 is used to detect locked motor conditions while the motor start sequence is in open loop.
For a successful startup, motor speed should equal to open to closed loop handoff threshold when the motor is transitioning into closed loop. However, if the motor is locked, the motor speed is not able to match the open loop drive rate.
If the motor BEMF is not detected for one electrical cycle after the open loop drive rate exceeds the threshold, then the open loop was unsuccessful as a result of a locked rotor condition.