Energy Technologies

This paper presents a hybrid-switched-capacitor-resonant (HSCR) light-emitting diode (LED) driver based on a stackable switched-capacitor (SC) converter IC rated for 15-20-W applications. Bulky transformers have been replaced with an SC ladder to perform high-efficiency voltage step-down conversion; an LC-resonant output network provides almost lossless current regulation and demonstrates the potential of capacitive galvanic isolation. The integrated SC modules can be stacked in the voltage domain to handle a large range of input voltage ranges that largely exceed the voltage limitation of the medium-voltage-rated 120-V silicon technology. The LED driver demonstrates >91% efficiency over a rectified input dc voltage range from 160 to 180 Vdc with two stacked ICs; using a stack of four ICs >89.6% efficiency is demonstrated over an input range from 320 to 360 Vdc. The LED driver can dim its output power to around 10% of the rated power while maintaining >70% efficiency with a pulsewidth modulation-controlled clock gating circuit.