摘要： There is a widespread application of selective dimming of multi-channel LED drivers. In this paper, two new selective dimming methods to improve efficiency of multi-channel LED drivers are proposed. The proposed methods are based on a two-stage multi-channel LED driver that consists of an ac-dc boost power factor correction converter at its front-end and a dc-dc non- resonant converter at its second stage. Primary side digital peak current control method is applied to the dc-dc converter to control the LED peak currents during selective dimming operation. The auxiliary back-to-back switches are connected across each transformer winding either at the primary side or secondary side to perform selective dimming. The duty ratios of these auxiliary back-to-back switches are varied at lower than switching frequency of dc-dc converter to control the brightness of LED loads. The proposed topologies offer high efficiencies in both full load and during selective dimming operations, and meet the IEEE 1789 recommendation with 3 kHz dimming frequency. The design of proposed dc-dc converters, modes of operation as well as detailed theoretical analysis are presented in this paper. A 150W prototype of the proposed LED driver with a non-DSP micro- controller, is implemented to verify the feasibility of such LED drivers. Comparisons between the proposed methods and the converters reported previously are presented in the paper.