| 摘要 |
A step-down switching regulator wherein the efficiency during a light load has been improved while the increase of circuit area being suppressed. A control circuit of the step-down switching regulator. When an output voltage (Vout) becomes lower than a reference voltage (Vref), an output monitor comparator (10) outputs an ON signal (SIG10). A pulse modulator (12) generates a pulse signal (SIG16) that exhibits a predetermined level for an ON time period (Ton) starting at the output of the ON signal (SIG10). A driver circuit (20) alternately turns on, based on the pulse signal (SIG16), a switching transistor (M1) and a synchronization/rectification transistor (M2) with a dead time period therebetween. A light-load mode detecting part (30) compares a ground potential with a switching voltage (Vsw) at a junction between the switching transistor (M1) and the synchronization/rectification transistor (M2), and nullifies the ON signal (SIG10) when the switching voltage (Vsw) is higher than the ground potential at a timing of the output of the ON signal (SIG10) from the output monitor comparator (10). ® KIPO & WIPO 2008
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