Design of a digital controller for an LED driver with a digital dimming

Abstract

This letter presents a new digital controller (DCL) with a new dimming method for high power-factor LED driver circuits. The core of proposed digital controller is based on a zero-voltage (ZVD) detection and a digital sine generator (DSG). By using the DSG, an effective dimming can be carried out easily. The proposed DCL was simulated and fabricated using the 1μm-650V DMOS process. The results obtained indicate that the inductor current waveform is in phase with the input voltage to gain a high power factor, because the inductor current is synchronized to the zero voltage signal from ZVD as expected. Also, the LED current changes according to the reference voltage, which is controlled by an external switch that adjusts the brightness of the LED.