Patent ID: 8324832

Claim:
A driving circuit for driving a light emitting diode (LED) light source, comprising: a power converter coupled to said LED light source and operable for receiving an input voltage from a power source and for providing an output voltage to said LED light source, said power converter comprising a switch coupled in series with said LED light source; a controller coupled to said power converter and operable for controlling a power of said LED light source by controlling said switch; a voltage-controlled current source coupled to said controller and operable for providing a first current, wherein said controller controls said switch based on said first current; and a first resistor coupled between said controller and ground, wherein said controller is operable for providing a second current, wherein a third current flowing through said first resistor is determined by a combination of said first current and said second current, wherein said controller is operable for adjusting said second current based on said first current to maintain said third current substantially constant, and wherein said controller is operable for generating a control signal based on said second current to control said switch.