| 摘要 |
PROBLEM TO BE SOLVED: To obtain a rectifying circuit which reduces a generated noise, which miniaturizes a power-supply apparatus and which makes the power-supply apparatus low cost, by a method wherein an auxiliary rectifying element is connected in parallel with a rectifying element and a spike-shaped voltage is rectified by the auxiliary rectifying element. SOLUTION: A coil L1 is connected to an input terminal VIN, and a transistor Q1 is connected in series with the coil L1. The transistor Q1 performs a switching operation so as to be turned on and off by the output of a PWM control circuit. A diode D1 is connected to the intermediate part between the coil L1 and the transistor Q1. Then, the sum of a back electromotive force generated in the coil L1 at a time when the transistor Q1 is turned off and an input terminal is rectified by the diode D1 so as to be smoothed by a capacitor C2, and an output voltage is obtained at an output terminal V01. A diode D2 and a diode D3 which are connected in series are connected in parallel with the diode D1. The diodes D2, D3 act as an auxiliary rectifying element, and a spike-shaped voltage which is superposed on square waves is rectified.
|
