Patent ID: 8411397

Claim:
A power supply apparatus for converting an alternating current to a direct current, comprising: a conversion component outputting a variable first voltage, the first voltage causing a first current, the first current having a predetermined phase region defined by at least one phase angle range of a waveform of the first current; a region determination circuit receiving both the first current and an average of the first voltage to determine whether the first current is in the predetermined phase region; an output component operably coupled to the conversion component, the output component outputting a load voltage; a sense component operably coupled to the conversion component, the sense component sensing a value indicative of a second current; and a switch element operably coupled to the conversion component, the switch element having a first state and a second state; wherein the switch element allows current to flow through the switch element in the first state and impedes current from flowing through the switch element in the second state; wherein the switch element changes between the first state and the second state based on a switch drive signal; wherein the switch drive signal forces the switch into the second state when the first current is determined to be in the predetermined phase region and the value indicative of the second current exceeds a threshold indicative of an overcurrent condition through the switch element.