When the motor is locked by some external condition, the DRV10974 device detects the lock condition and acts to protect the motor and the device. The lock condition must be properly detected whether the condition occurs as a result of a slowly increasing load or a sudden shock.

The DRV10974 device reacts to the lock condition by stopping the motor drive. To stop driving the motor, the phase outputs are placed into a high-impedance state. After successfully transitioning into a high-impedance state as the result of a lock condition, the DRV10974 device attempts to restart the motor after t_{(LOCK_OFF)} seconds.

The DRV10974 device has a comprehensive lock-detect function that includes six different lock-detect schemes. Each of these schemes detects a particular condition of the lock as shown in #T4509467-33.

Figure 7-8 Lock Detect

The following sections describe each lock-detect scheme.