| 摘要 |
PROBLEM TO BE SOLVED: To enable a soft switching operation to be performed with a small number of components in a synchronous rectification type step-up chopper circuit, thereby enabling enhancement in efficiency and reduction in noise and cost.SOLUTION: A switching power supply device includes a main switching element 14, a rectifying element 16, an output choke coil 18, and an output capacitor 20. The inductance of the output choke coil 18 is set to such a predetermined value that choke coil current IL flowing through an output choke coil 18 flows in both positive and negative directions within one cycle of switching when the output current is not more than a rated value. A switching control circuit 24 controls the main switching element 14 and the rectifying element 16 so that the main switching element 14 and the rectifying element 16 are complementarily turned on and off with a dead time in a predetermined switching cycle, thereby making the main switching element 14 and the rectifying element 16 performing soft switching.SELECTED DRAWING: Figure 1 |
