Patent ID: 8169160

Claim:
A circuit for driving a light emitting diode (LED) light source, said circuit comprising: a converter for converting an input voltage to an output voltage across said light source based upon a driving signal, wherein a duty cycle of said driving signal determines an average current flowing through said LED light source; a sensor selectively coupled to and decoupled from said converter based upon said driving signal, and for generating a sense voltage indicative of a current flowing through said LED light source when said sensor is coupled to said converter; and a controller coupled to said converter and said sensor and for comparing said sense voltage to a reference voltage indicative of a predetermined average current through said LED light source to generate a compensation signal and for generating said driving signal based upon said compensation signal, wherein said duty cycle of said driving signal is adjusted based upon said compensation signal to adjust said average current flowing through said LED light source to said predetermined average current, wherein said controller further comprises a feedback circuit coupled to said sensor and for comparing said sense voltage to said reference voltage to generate said compensation signal and for outputting a reset signal by comparing said compensation signal to a ramp signal, wherein said feedback circuit further comprises: an amplifier for comparing said sense voltage to said reference voltage to generate an output current; a charging path coupled to said amplifier and for charging an energy storage element with said output current to produce said compensation signal; and a comparator coupled to said charging path and for comparing said compensation signal to said ramp signal to generate said reset signal, wherein said charging path further comprises: a first switch coupled to said feedback circuit and for alternating between cutting said charging path off and conducting said charging path based upon a control signal that is generated according to said reset signal and a pulse signal.