Patent ID: 7352599

Claim:
A switching power source apparatus for ON/OFF-controlling an input AC voltage with a switching element and converting the input AC voltage into a DC voltage that is higher than the AC voltage and is supplied as an output voltage, comprising: an error amplifier configured to provide an error voltage representative of a difference between the output voltage and a first reference voltage; a controller configured to control the switching element according to the error voltage, the controller turning off the switching element when a predetermined ON-time is reached; and a variable reference voltage generator configured to generate the first reference voltage according to the error voltage, wherein the variable reference voltage generator comprises: an error voltage comparator configured to compare the error voltage with a second reference voltage, and adapted, if the error voltage is greater than the second reference voltage, to provide a switching signal; and a reference voltage switch configured to switch the first reference voltage to a lower reference voltage in response to the switching signal and provide the error amplifier with the lower reference voltage.