SWITCHING REGULATOR, POWER CIRCUIT UTILIZING THE SWITCHING REGULATOR, AND SECONDARY BATTERY CHARGING CIRCUIT UTILIZING THE SWITCHING REGULATOR

摘要

PPROBLEM TO BE SOLVED: To provide a switching regulator, a power circuit utilizing the switching regulator, and a secondary battery charging circuit utilizing the switching regulator capable of preventing current counter flow without using a counter-flow preventing diode, even when a PMOS transistor is used as a switching element for a step-down switching regulator. PSOLUTION: A changeover switch SW1 is provided that changes over connection at a substrate gate of a switching transistor M1. An input/output comparison circuit 6 is configured to control the changeover switch SW1 so as to connect the substrate gate to the drain against the switching transistor M1 when a voltage of an input terminal IN is equal to or lower than that of an output terminal OUT, and to control the changeover switch SW1 so as to connect the substrate gate to the source against the switching transistor M1 when the voltage of the input terminal IN exceeds that of the output terminal OUT. PCOPYRIGHT: (C)2006,JPO&NCIPI