Patent ID: 8330388

Claim:
A dimming controller for controlling power of a light emitting diode (LED) light source, comprising: a monitoring terminal operable for receiving a current monitoring signal indicating a current flowing through said LED light source; a dimming terminal operable for receiving a ramp signal, wherein a voltage of said ramp signal increases if a power switch coupled between a power source and said LED light source is turned on; a control terminal operable for providing a control signal to control a control switch coupled in series with said LED light source based on said current monitoring signal and said ramp signal; a pulse-width modulation signal generator operable for generating a pulse-width modulation signal based on said ramp signal, wherein a duty cycle of said pulse-width modulation signal is determined by said ramp signal; a sawtooth signal generator operable for generating a sawtooth signal; and a comparator operable for comparing said ramp signal with said sawtooth signal to generate said pulse-width modulation signal, wherein an average current flowing through said LED light source increases as said ramp signal increases until said average current reaches a predetermined level.