| 摘要 |
PROBLEM TO BE SOLVED: To reduce a voltage applied to a switching element for the reduced size and enhanced efficiency of equipment by providing a means for driving a first switching element and a second switching element in the same phase. SOLUTION: A control circuit A3 supplies a pulse signal of waveform to the gate of a transistor T4 and a drive circuit A1, and drives switching elements T4 and T3 in the same phase. During a period when the switching elements T3 and T4 are on, a current is passed through a closed circuit consisting of a direct-current power supply Vcc, the switching element T3, the primary winding L1 of a transformer TF2, and the switching element T4. As a result, a current is passed through the secondary winding L2 of the transformer TF2 due to magnetic fields produced in the primary winding L1 of the transformer TF2. This current is rectified and smoothed through a rectifying and smoothing circuit A2 and supplied to a load R. Thus, a small-sized switching power supply can be designed. Further, the efficiency of the switching power supply can be enhanced.
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