Patent ID: 7796867

Claim:
A motor drive apparatus for use with a motor to be driven, the motor drive apparatus comprising: a first pulse width modulation comparator which compares a temperature detection voltage that depends on temperature, with a cyclic voltage, and outputs a first pulse with modulation signal; a second pulse width modulation comparator which compares a minimum frequency setting voltage indicating a minimum frequency of the motor that is to be driven, with the cyclic voltage, and outputs a second pulse width modulation signal; and a drive circuit which combines the first and the second pulse width modulation signals outputted from the first and the second pulse width modulation comparators, by a logical operation, to drive the motor that is to be driven, wherein the drive circuit comprises: a first logic gate which generates a logical sum of the first and the second pulse width modulation signals; a second logic gate which generates a logical product of one of the first and the second pulse width modulation signals, and an inverted signal of another of the first and the second pulse width modulation signals; and a selector which switches between a first drive mode based on an output signal of the first logic gate, and a second drive mode based on an output signal of the second logic gate.