Patent ID: 8009444
Filing Date: 2011-08-30
Classification: H02M

Abstract:
1. A boost device for boosting an input voltage supplied by an external power source to an output voltage, comprising: a transformer having first and second windings each having opposite first and second ends, said first end of said first winding being adapted to be coupled to the external power source; a first switch coupled between a reference node and said second end of said first winding of said transformer, and operable between an ON-state and an OFF-state; a clamp circuit adapted to be coupled to the external power source, coupled across said first winding of said transformer, and including a series connection of a clamp capacitor and a second switch, said second switch being operable between an ON-state and an OFF-state; an output diode having an anode coupled to said first end of said second winding of said transformer, and a cathode; an output capacitor having a first terminal coupled to said cathode of said output diode, and a second terminal, the output voltage being a voltage across said output capacitor, said output capacitor being capable of being charged through said output diode with an induced voltage across said second winding of said transformer; and a boost circuit coupled to said anode of said output diode and said second terminal of said output capacitor, and across said second winding of said transformer, said boost circuit being capable of being charged with the induced voltage across said second winding of said transformer, and of charging said output capacitor through said output diode so as to boost the voltage across said output capacitor; wherein said boost circuit includes a first capacitor coupled between said second end of said second winding of said transformer and said second terminal of said output capacitor, said output capacitor being further charged through said output diode with a voltage across said first capacitor when said output capacitor is charged with the induced voltage across said second winding of said transformer.