| 摘要 |
PROBLEM TO BE SOLVED: To provide power supply equipment which prevents abnormal boosting of a voltage impressed on a components, prevents thereby breakdown of the component and enhances safety. SOLUTION: An electrolytic capacitor C2 is connected between output terminals of a full-wave rectifier circuit DB with a high-speed diode D1 and a load circuit L interposed. A series circuit of a diode D2 and FET Q1 is connected to the opposite ends of the electrolytic capacitor C2 . Besides, a choke coil L2 is connected between the node of the high-speed diode D1 and the load circuit L and the node of the diode D2 and the FET Q1 . Since a booster chopper operation and a step-down chopper operation are conducted in combination only in the case when a voltage VL is equal to a difference between a voltage Vc2 and the absolute value |VIN| of a voltage VIN (VL=VC2 -|VIN|) at the time of ON/OFF of the FET Q), a period when the booster chopper operation is conducted is vanishes or becomes short in the case when the impedance of the load, circuit L is small, and thus abnormal boosting of the voltage Vc2 is prevented. |
