ZHCSDA7G July 2014 – February 2018 DRV10983
If motor is operating normally, the motor BEMF should always be less than output amplitude. The DRV10983 uses two methods of monitoring the BEMF in the system. The U phase current is monitored to maintain an estimate of BEMF based on the setting for Rm[6:0]. In addition, the BEMF is estimated based on the operation speed of the motor and the setting for Kt[6:0]. Figure 31 shows the method for using this information to detect a lock condition. If motor BEMF is much higher than output amplitude for a certain period of time, tLCK_ETR, it means the estimated speed is wrong, and the motor has gotten out of phase.