Patent ID: 7710049
Filing Date: 2010-05-04
Classification: H05B,Y02B

Abstract:
1. A LED drive circuit comprising: a boost circuit configured for receiving an input voltage and providing an output voltage according to a control signal; at least two branch circuits, each including a plurality of LEDs connected in series and providing a feedback signal representative of a current flowing therein, thus there are at least two feedback signals, each of the branch circuits further including a branch switch and a feedback resistor connected in series with the LEDs; a selector configured for alternatively selecting one of the feedback signals as an output feedback signal and switching on or off a corresponding one of the two branch circuits, the selector including a first selecting unit and a second selecting unit, wherein: a pulse-width modulation (PWM) controller configured for generating a pulse-width modulation signal as the control signal for the boost circuit according to the output feedback signal of the selector.