Multiple-output dimmable LED driver with flyback converter

Abstract

In this paper, a multiple-output dimmable LED driver with flyback converter is designed and implemented. The sequences and conducting times of red (R), green (G), and blue (B) control switches are determined by the voltage level from the primary-side digital signal processor. The flyback converter with primary-side control is operated in quasi-resonant mode, frequency limitation with the valley switching mode, and frequency reduction mode according to the dimming level and input voltage conditions. Finally, a 20 W flyback LED driver for red (24.5 V/ 0.2 A), green (36.8 V/ 0.2 A), and blue (37.5 V/ 0.2 A) LED outputs with the universal input voltages 90–264 Vrms is designed and implemented. The dimming range for each output can be varied from 5 %–100 %. The line regulation for 5 %–100 % dimming level of RGB outputs is within 7 %. The maximum errors for the non-dimming (100 % dimming) and dimming conditions are 2.9 mA and 3.6 mA, respectively. The highest system efficiency at full load condition is 85.54 %.