The 1st switching element which is jointed in series to the power source

摘要

PROBLEM TO BE SOLVED: To stop power consumption output, with a simple and low-cost configuration, by safely discharging the charges accumulated in a capacitor corresponding to a control signal from outside, without causing power consumption to increase.;SOLUTION: In the power supply unit, a first switch 8 is disposed in between an input power supply and an input terminal of a switching control circuit 20, an output capacitor 5 is disposed between the input terminal and a GND of the switching control circuit 20, a diode 6 is disposed between the switching control circuit 20 and the output of a DC/DC convertor, a time constant circuit 25 is disposed between the reference voltage input terminal and the reference voltage source of the error amplifier 201 of the switching control circuit 20, and a second switch 24 is disposed, in parallel with the reference voltage source. An output ON/OFF signal from the outside is supplied to the first switch 8, and an inversion (40) signal of the output ON/OFF signal is supplied to the second switch 24.;COPYRIGHT: (C)2009,JPO&INPIT