| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a PWM signal output circuit that can gradually change a current through a motor coil in a compact circuit scale. <P>SOLUTION: The PWM signal output circuit for a drive circuit for driving a motor on the basis of a PWM signal includes: a division section for dividing into first to third periods a period detected by a detection section for detecting respective periods for which a speed signal is at one logic level and at the other logic level in response to the rotating speed of the motor; a first output section for, in the first period, controlling the duty ratio of the PWM signal to be output such that the duty ratio of the PWM signal changes stepwise so as to increase a current flowing through a motor coil; a second output section for, in the second period, controlling the PWM signal to be output to the duty ratio of an input signal so as to keep the current flowing through the motor coil constant; and a third output section for, in the third period, controlling the duty ratio of the PWM signal to be output to a stepwise change so as to reduce the current flowing through the motor coil. <P>COPYRIGHT: (C)2013,JPO&INPIT |
