| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power circuit capable of operating, even when a source voltage such as a battery voltage, etc., is lower, and being a small circuit scale. SOLUTION: This is a power circuit which has, in a route from a battery voltage VB up to a terminal J OUT for supplying an operating voltage VO to a CPU, a driving circuit 16 which turns on/off a P-channel MOSFET 7 whose source and drain are connected in series according to a driving signal, a smoothing circuit 15 which smoothes the drain voltage of the FBT 7 and outputs it to the above-mentioned terminal J OUT, and a driving signal outputting circuit 30 which outputs a driving signal to the driving circuit 16 so that the voltage VO of the terminal J OUT may be a set voltage. The driving circuit 16 has two transistors 25, 27 which connect a negative-side charge pump circuit 23 which generates a negative voltage, and the gate of the FET 7 to the output terminal J PO of the negative-side charge pump curcuit 23 and a ground voltage through two diodes 19, 21 respectively, as a turn-on driving unit which turns the FET 7 on.
|
