| 摘要 |
PROBLEM TO BE SOLVED: To suppress a change of the timing of starting intermittent oscillation control.SOLUTION: A switching power supply 1 having an LLC resonant circuit and switch elements Q1, Q2 detects an error between a voltage value of an output voltage and a target value of the output voltage determined by a supply voltage of a reference voltage source Vref, and changes a voltage of a first terminal P1 in accordance with the detection result. An input voltage detection section 20 detects an input voltage or a voltage depending on the input voltage, and a control circuit 10 sets a maximum oscillation frequency of the switching power supply 1 in accordance with the voltage detected by the input voltage detection section 20. The control circuit 10 further controls an on-off frequency of the switch elements Q1, Q2 on the basis of the maximum oscillation frequency thus set and the voltage of the first terminal P1. |
