| 摘要 |
<p>When an AC power supply (9) is turned on, a constant current supply section (14) supplies a constant current to a capacitor (C3) and charges the capacitor (C3). When the voltage across the capacitor (C3) reaches a specified level, a switch control section (17) turns a switch (13) off. When the output current lowers to lighten the load, a load detection circuit (15) stops the operation of a PWM control circuit (12) and actuates a timer (16). Upon elapsing a specified time, the timer (16) delivers a switch-on signal to the switch control section (17) that turns on the switch (13) when supplied with the signal. Consequently, the capacitor (C3) is charged again and a voltage is applied to the PWM control circuit (12).</p> |
