| 摘要 |
PROBLEM TO BE SOLVED: To provide a power-supply circuit that allows reducing loss in a switching element or a capacitor and easy controlling of switching at a primary side and a secondary side.SOLUTION: A power-supply circuit includes: a switching circuit outputting an AC voltage; a transformer having first to third coils; a rectifier circuit rectifying an output from the second coil; a power conversion circuit having at least one first rectifier, a second switching element, a second rectifier, an inductive element, and a capacitive element; and a control circuit controlling switching timing. The control circuit progressively increases a first duty ratio of the switching of the switching circuit, and performs on and off control of the second switching element by a second duty ratio larger than the first duty ratio until an output voltage across the capacitive element reaches a predetermined output. |
