Patent ID: 8760099

Claim:
A back electromotive force (EMF) detector for a motor, comprising: an upper switch, comprising a first terminal coupled to a reference voltage source and a second terminal coupled to a driving voltage, and controlled by a first control signal; a lower switch, comprising a first terminal coupled to said second terminal of said upper switch and controlled by a second control signal; a current sensing resistor, serially connected between a second terminal of said lower switch and a reference ground voltage; a first resistance provider, comprising a first terminal coupled to said second terminal of said upper switch, and a back EMF detection result is generated at a second terminal of said first resistance provider; a second resistance provider, connected between said second terminal of said first resistance provider and said reference ground voltage; and a third resistance provider, connected between a coupled terminal of said first and second resistance providers, and said second terminal of said lower switch, wherein, resistance values of said first to third resistance providers are determined by at least one characteristic parameter of said motor.