JPS6412869A - Switching power source device - Google Patents

Abstract

PURPOSE:To restrain a transient excessive current, by providing a delay circuit, delaying the output of a secondary winding. CONSTITUTION:The voltage of an AC input power source 1 passes through a fuse 2, a power source switch 3 and a limiting resistor 4 and is converted into a DC voltage by a rectifying diode 5 and a smoothing capacitor 6, thereafter, is impressed on a switching element 7 as a starting voltage. Counterelectromotive forces are generated in respective windings of a switching transformer 9 and converted into DC voltages through rectifying diodes 17, 18 and smoothing capacitors 19, 20, and they are outputted. A power is supplied to a large power load 23 by a method wherein the power is supplied to a small power load 22 at first to conduct a switching element 21, thereafter, the power is passed through a delay circuit block 31 or a diode 32 based on the voltage of this line and, then, the power is passed through a charging capacitor 33 and delay time setting resistors 34, 35. According to this method, the switching element 21 is conducted and the power may be supplied to the large power load 23.