STEP-UP/STEP-DOWN SWITCHING REGULATOR, AND REVERSE-CURRENT PREVENTION METHOD FOR THE STEP-UP/STEP-DOWN SWITCHING REGULATOR

摘要

PPROBLEM TO BE SOLVED: To obtain a step-up/step-down switching regulator and a reverse-current prevention method for a step-up/step-down switching regulator that prevent the occurrence of reverse current, even when using a MOS transistor for a rectifying element. PSOLUTION: Voltages at both ends of a step-up synchronous rectifying transistor M4 are compared with each other by a comparator 11; a reverse current is detected, while the direction of the current flowing in the step-up synchronous rectifying transistor M4 is detected; and so that when reverse current is detected, a step-down switching transistor M1 and a PMOS transistor M5 are respectively turned off. PCOPYRIGHT: (C)2008,JPO&INPIT