| 摘要 |
<p>In a normal operation mode, a mode changeover controller (8) continuously operates a PWM control circuit (6) so as to operate a switching element (5) at the basic oscillation frequency. In a standby mode, the mode changeover controller (8) intermittently operates the PWM control circuit (6) so as to turn on the switching element (5) at a given repetition interval and for a given time period. This repetition interval is shorter than a time for decreasing an output voltage from a rectifying and smoothing circuit (20) down to a guaranteed load operating voltage due to power consumption of the load (30) and the rectifying and smoothing circuit (20) in the standby mode and is longer than a time for entering a sonic frequency band. That time period is longer than a time for stabilizing an output from the rectifying and smoothing circuit (20) and is also longer than a time for entering a sonic frequency band. <IMAGE></p> |
