Sensorless motor driver with BEMF mask extender
A motor control circuit wherein Bemf zero crossings are sensed to provide phasing information. To avoid incorrect timing (due to detection of zero crossings which may be caused by switching noise when the power transistors switch to commutate other phases), the Bemf detection is masked. Advantageously, the Bemf detection is masked not only for the normal masking period (including an additional percentage beyond the minimum period), but is also for an additional period, if the Bemf output is not of the expected polarity.