STEP-UP/DOWN SWITCHING REGULATOR, ITS CONTROL CIRCUIT, AND ELECTRONIC APPARATUS USING SAME

摘要

A switching regulator of synchronous rectifying type capable of blocking the current flowing when voltage step-up/down operation is stopped without providing any DC current preventive transistor. An input voltage Vin is supplied to a first terminal (102) of a control circuit (100) through an inductor (L1) connected to the outside. An output capacitor (Co) is connected to a second terminal (104). A switching transistor (SW1) is disposed between the first terminal (102) and the ground, and a synchronous rectifying transistor (SW2) is disposed between the first and second terminals (102, 104). A first transistor (M1) is disposed between the back gate of a synchronous rectifying transistor (M2) and the first terminal (102), and the second transistor (M2) is disposed between the back gate and the second terminal (104). A switching control section (12) keeps the first and second transistors (M1, M2) off during a step-up stop period and keeps the first transistor (M1) off and the second transistor (M2) on during a step-up period.