PURPOSE: To obtain secondary output voltages of more than one system without enlarging the scale of a circuit by forming a charge pump of a capacitor and a diode and employing the output from a booster coil as a switching signal in a switching regulator comprising the booster coil and a transistor.

CONSTITUTION: An input voltage VIN is fed through a booster choke coil L1 to a FET Q1 and through a diode D1 to a smoothing filter 2. The transistor Q1 operates with a switching pulse PSW fed from a PWM circuit 3 and outputs a first secondary output voltage VOUT1 through the smoothing filter 2. Thus the smoothed voltage is fed through a control circuit 6 back to the PWM circuit 3. A second secondary output voltage VOUT2 is obtained by providing a charge pump type DC-DC converter comprising diodes D5, D6 and capacitors C20, C30 and employing the output of the booster choke coil L1 as a switching signal for the capacitor 20.