MOTOR DRIVE DEVICE AND COOLING DEVICE USING THE SAME

摘要

There is provided a drive circuit for a fan motor. In the drive circuit (100), a first PWM comparator (22) compares a temperature detection voltage Vth to a cyclic voltage Vosc and outputs a first PWM signal Vpwm1. A second PWM comparator compares a lowest rpm setting voltage Vmin indicating the lowest rpm of the fan motor (110) to the cyclic voltage Vosc and outputs a second PWM signal Vpwm2. The drive circuit (30) combines the first PWM signal Vpwm1 and the second PWM signal Vpwm2 by a logical operation so as to drive the fan motor (110). The drive circuit (30) includes a first logic gate generating OR of the first PWM signal Vpwm1 and the second PWM signal Vpwm2 and a second logical gate generating AND of the first PWM signal Vpwm1 and a reversed signal of the second PWM signal Vpwm2. The drive circuit (30) switches the drive mode according to the first logical gate and the second logical gate.