A Novel Fixed-Frequency Dimming Scheme with Ultra-Wide, High-Frequency Dimming Range

摘要

This paper presents a novel fixed-frequency dimming scheme that achieves ultra-wide dimmingrnrange at high dimming frequencies. The scheme utilizes a controlled on-time buck–rnbased LED driver in conjunction with a shunt-dimming technique. The LED driver’s controlledrnon-time is adjusted relative to the shunt-dimming signal to maximize the dimming ratio and tornmaintain a constant frequency of operation across the various operating modes. The performancernadvantages as well as the limitations of the proposed scheme are discussed. Arnprototype circuit is used to evaluate the proposed dimming configuration, and experimentalrnresults are also given.