| 摘要 |
PROBLEM TO BE SOLVED: To provide a small switching power supply apparatus which enables simple circuit structure and operates efficiently even if an input voltage or load changes. SOLUTION: An inductor Lr, a transformer T, a first switch circuit S1, a second switch circuit S2, and a capacitor Cr are connected so as to control an output voltage Vo by performing on/off control of a first switching element Q1 and a second switching element Q2 alternately, obtaining an output from a secondary winding ns of the transformer T, and controlling the time the Q1 is turned on. A first rectifying/smoothing circuit RS1 is connected to the secondary winding ns of the transformer T. A first control circuit SC1 is operated by a DC current supplied from a second rectifying/smoothing circuit RS2, and after the second switching element Q2 is turned on, the second switching element Q2 is forcibly turned off at predetermined timing by a turn-off circuit TC of a second control circuit SC2 which is operated by an AC current. COPYRIGHT: (C)2009,JPO&INPIT
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