| 摘要 |
PROBLEM TO BE SOLVED: To suppress variation of switching frequency, without impairing the advantages of a nonlinear control system.SOLUTION: A switching power supply 1 comprises: a switching control unit (13, 14, 16-18) of nonlinear control system generating an output voltage OUT from an input voltage IN by performing on/off control of switch elements (11 and 12) depending on the comparison results of a feedback voltage FB and a reference voltage REF; a reverse current detection unit 19 for turning the switch element off forcibly by detecting a reverse current to the switch element; and an on time setting unit 15 for setting the on time of the switch element depending on the duty thereof when the reverse current is not detected, and setting the on time of the switch element depending on a switch voltage SW (or output voltage OUT) appearing at one end of the switch element when the reverse current is detected. |
