| 摘要 |
PROBLEM TO BE SOLVED: To provide a synchronous rectifying switching power unit, which can perform a proper switching operation even if an output current drops to below a critical point. SOLUTION: The switching power unit comprises first and second transistors 11, 12 connected in series between one terminal and the other terminal of a DC power source 10, a diode 13 connected in parallel to the second transistor 12, an inductor 16 connected between the node of the first and second transistors 11, 12 and one terminal of a load 15, an output capacitor 17 connected in parallel to the load 15, a control circuit 18 generating a control signal C for controlling on/off of the first and second transistors 11, 12, and a means for turning the transistor 12 off, irrespective of the control signal C, in response to the situation where the output current flowing in the load 15 is below a prescribed value.
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