Patent ID: 7782634

Claim:
A switched-mode power supply comprising: a converter to convert input power into output power having a predetermined voltage by performing a switching operation; a light emitting unit to emit light indicative of the voltage of the output power if the voltage of the output power is equal to or greater than a predetermined threshold voltage; a light receiving unit to receive the light emitted from the light emitting unit and output a signal indicative of the voltage of the output power; an output power voltage indicating unit to receive the signal indicative of the voltage of the output power output from the light receiving unit and output an indication of the voltage of the output power; and a switching controller to control the switching operation of the converter according to the indication of the voltage of the output power output from the output power voltage indicating unit; wherein the output power voltage indicating unit comprises a switching unit to vary a characteristic of the output power voltage indicating unit according to a size of a load receiving the output power converted by the converter.