Patent ID: 8107262

Claim:
A variable switching frequency type power supply comprising: a switching unit configured to switch input power; a transformation unit configured to convert a voltage level of the power switched by the switching unit into a predetermined voltage level; a rectification unit configured to rectify the power converted by the transformation unit; and a control unit configured to fix a switching duty cycle of the switching unit to a predetermined switching duty cycle, and varying switching frequency of the switching unit according to a voltage level of output power, wherein the transformation unit comprises: a transformer configured to convert the voltage level of the power switched by the switching unit according to a predetermined turns ratio between a primary winding electrically coupled to the switching unit and a secondary winding electrically coupled to the rectification unit; a series boost capacitor connected in series between the switching unit and the primary winding of the transformer and configured to boost the power switched by the switching unit; and a magnetized inductor connected in parallel with the primary winding of the transformer, and resonating with the series boost capacitor, wherein a resonant frequency of the series boost capacitor and the magnetized inductor is lower than the switching frequency of the switching unit.