Abstract:
A circuit and method provide a back EMF signal that represents a back EMF voltage induced in a coil of a brushless motor. In one embodiment of the invention, the circuit includes an input node operable to receive a tap voltage from the coil, and a network coupled to the input node and operable to generate the back EMF signal by removing a predetermined offset voltage from the tap voltage. Such a circuit provides a signal that more accurately indicates a zero crossing than existing circuits for controlling a sensorless brushless motor.