| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce power consumption of a digital control circuit used for a power supply circuit except when the load is small, i.e., even when the duty ratio of a PWM signal exists. <P>SOLUTION: When the duty ratio of a PWM signal exists and the duty ratio of the PWM signal is constant for a certain period, a feedback control circuit is operated intermittently with the duty ratio fixed. Specifically, a power supply circuit comprises: an A/D converter circuit for forming a digital value based on an analog value obtained by monitoring the output voltage based on a reference voltage; a digital filter circuit for smoothing the digital value; a PWM signal generation circuit for generating a PWM signal based on the output value of the digital filter circuit; and an operation mode control circuit for controlling the circuit operation mode based on the duty ratio of the PWM signal. <P>COPYRIGHT: (C)2012,JPO&INPIT |
