Patent ID: 8581514
Filing Date: 2013-11-12
Classification: H05B

Abstract:
1. A dimming circuit for supplying an output voltage to a LED according to a dimming signal provided by a functional IC, the dimming circuit comprising: a selector connected to the functional IC, being controlled by the dimming signal to select one of a first driving voltage setting signal and a second driving voltage setting signal as an output of the selector; a power source connected to the functional IC and the selector, providing a first driving voltage or a second driving voltage as the output voltage according to the output of the selector, and supplying the output voltage to the functional IC; and a voltage setting circuit connected to the selector, providing the first driving voltage setting signal and the second driving voltage setting signal; wherein the voltage setting circuit comprises: a current sense resistor connected to the LED, detecting a current of the LED to generate a feedback signal; a first error amplifier connected to the selector and the current sense resistor, amplifying a difference between the feedback signal and a first reference voltage to generate the first driving voltage setting signal; and a second error amplifier connected to the selector and the power source, amplifying a difference between the output voltage and a second reference voltage to generate the second driving voltage setting signal, the second reference voltage is controlled by an off voltage setting signal different from the dimming signal.