| 摘要 |
PROBLEM TO BE SOLVED: To provide a step-down switching regulator in which conversion efficiency is improved under a light load. SOLUTION: The control circuit 100 of a step-down switching regulator applies a switching voltage Vsw to an inductor L1. A driver circuit 10 creates first and second gate voltages Vg1 and Vg2 which are applied to the gate terminal of each transistor based on a PWM signal Vpwm. A comparing section 30 outputs a high level comparison signal Vcmp when Vsw>0 V. During a period where a transistor M2 for synchronous rectification must be turned on, a latch circuit 40 latches the comparison signal Vcmp and outputs it as a detection signal Vsens. During a period where the detection signal Vsens is latched to high level, a forced off switch SW1 fixes the gate voltage of the transistor M2 for synchronous rectification to 0 V. COPYRIGHT: (C)2007,JPO&INPIT
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