Patent ID: 7362078

Claim:
A power supply circuit for receiving an input voltage at an input terminal, converting the input voltage to an output voltage and outputting the output voltage to a load connected to an output terminal, comprising: a power supply circuit unit for converting the input voltage to a predetermined constant voltage and outputting the converted voltage to the output terminal, the power supply circuit unit operating in accordance with a first control signal; an output current detecting circuit unit for detecting a current output from the power supply circuit unit, and outputting a second control signal when the detected current is smaller than a predetermined value i1; and an output voltage detecting circuit unit for detecting a voltage output from the power supply circuit unit, and operating while the output current detecting circuit unit outputs the second control signal, the output voltage detecting circuit unit stopping operation of the power supply circuit unit with the first control signal when the detected voltage exceeds a predetermined value Vdet 1 ; whereby the output supply voltage detecting circuit unit causes the power supply circuit unit to operate when the detected voltage becomes equal to or lower than a predetermined value Vdet 2 that is lower than the predetermined value Vdet 1 , thereby the power supply circuit unit performs intermittent operations.