| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply that reduces power consumption and suppresses an output ripple in a middle load condition.SOLUTION: The switching power supply includes: a transformer having a primary winding on a primary side and having a secondary side isolated from the primary side; a switching element connected to the primary winding of the transformer; current detection means for detecting a voltage depending on a current flowing on the primary side of the transformer when the switching element is driven; feedback means for feeding a voltage depending on a voltage output to the secondary side back to the primary side; and control means for controlling the operation of the switching element on the basis of the voltage detected by the current detection means and the voltage from the feedback means. The control means compares the voltage from the feedback means with a predetermined reference voltage, and controllingly restricts or derestricts an upper limit of a driving pulse time to drive the switching element according to the result of comparison to determine the driving time of the switching element. |
