Patent ID: 7250735

Claim:
A driving circuit of a fan comprising: a magnetic pole sensor, for generating a magnetic pole sensing signal according to alternation of magnetic pole of a rotor of the fan; a first waveform generator coupled to the magnetic pole sensor, for generating a first waveform according to the magnetic pole sensing signal generated by the magnetic pole sensor; a second waveform generator, for generating a second waveform; a comparison circuit coupled to the first waveform generator and the second waveform generator, for comparing the first waveform and the second waveform for generating a third waveform; a control signal generator coupled to the comparison circuit, for generating a control signal according to the third waveform generated by the comparison circuit and an external signal; and a current generator coupled to the magnetic pole sensor and the control signal generator, for outputting current to a coil of a stator of the fan according to the magnetic pole sensing signal generated by the magnetic pole sensor and the control signal generated by the control signal generator.