| 摘要 |
PROBLEM TO BE SOLVED: To save power of a switching power supply and suppress a reduction in output voltage when a sudden change in load occurs.SOLUTION: A switching power supply comprises: a switching element that is connected with a primary winding of a transformer; detection means that detects a signal according to a current flowing on a primary side of the transformer; feedback means that feeds back a signal according to a voltage output from a secondary winding on a secondary side of the transformer to the primary side; change amount detection means that detects the amount of change in the signal from the feedback means; and time determination means that compares the signal from the feedback means with a reference value and limits an on-time of the switching element according to a result of the comparison. When the amount of change detected by the change amount detection means is equal to or more than a predetermined value, the time determination part releases the limitation of the on-time of the switching element.SELECTED DRAWING: Figure 1 |
