Patent ID: 8513834

Claim:
A power supply apparatus comprising: a direct current power source; a plurality of voltage converting circuits; a clock generation section which generates a plurality of clocks for driving each of said plurality of voltage converting circuits; and a power adjustment circuit which controls an output from the direct current power source according to a driving state of each of said plurality of voltage converting circuits, wherein each of said voltage converting circuits includes: a transformer where an output from the direct current power source is supplied to a primary coil thereof; an output section which is connected to a secondary coil of the transformer and generates an output voltage; a comparator which compares between a target value of the output voltage and the output voltage value output from the output section; and a switching section which controls a drive duty of the transformer according to the clock and the comparison results of the comparator, and wherein the power adjustment circuit includes: a detection unit which detects the drive duty ratio of each of the transformers of the plurality of voltage converting circuits; and a direct current power source adjustment unit which compares the duty ratio of each of said plurality of voltage converting circuits with a predetermined value and based on the comparison results, adjusts the output of said direct current power source supplied to the primary coil of the transformer.