| 摘要 |
PROBLEM TO BE SOLVED: To prevent an excessive current (through current) from flowing to a primary-side switching element under a light load.SOLUTION: A power supply device comprises a DC/DC converter. The DC/DC converter comprises: a full bridge circuit; a transformer including a primary-side coil to which the full bridge circuit is connected, and a secondary-side coil which is insulated from the primary-side coil; a synchronous rectifier circuit which is connected to the secondary-side coil; and a control part which controls a first switching element and a second switching element that are connected to a first end of the primary-side coil by a predetermined fixed duty, controls a third switching element and a fourth switching element that are connected to a second end of the primary-side coil by pulse width modulation, and turns on a fifth switching element and a sixth switching element that the synchronous rectifier circuit includes, for at least a predetermined period just before the third switching element and the fourth switching element are turned off.SELECTED DRAWING: Figure 1 |
