| 摘要 |
PROBLEM TO BE SOLVED: To reduce a gate drive current at a light load during suppressing on-resistance at heavy load. SOLUTION: A driver circuit 20 complementarily turns on/off a switching transistor M1 and a transistor M2 for synchronous rectification. The switching transistor M1 and the transistor M2 for synchronous rectification are formed, by being divided into two segments PMOS1, PMOS2, NMOS1, NMOS2 capable of independently controlling the on/off operations, respectively. A load-monitoring circuit 40 monitors a load state of a step-down switching regulator 200. The driver circuit 20 reduces the number of segments where the switching transistor M1 and the transistor M2 for the synchronous rectification drive, as they go into a light-load condition. COPYRIGHT: (C)2007,JPO&INPIT
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