A Hybrid LED Sink Driver Combining a Buck-Boost Converter and a Switched-Capacitor Step-Up Converter with Nested Topology

Abstract

Abstract For LED lighting applications, this paper presents a novel light emitting diode (LED) sink driver with high voltage gains. Unlike traditional LED sink drivers, the proposed LED sink driver consists of a buck-boost converter and a switched-capacitor (SC) step-up converter with nested topology, where an input voltage is converted twice by cascading these two converter blocks. Therefore, the proposed hybrid topology enables the LED sink driver to achieve not only flexible control of an output voltage but also high voltage gains and few passive components. The characteristics of the proposed LED sink driver are investigated by theoretical analysis, simulation program with integrated circuit emphasis (SPICE) simulations, and breadboard experiments. In the performed simulations, the power efficiency of the proposed driver reaches about 80 % at 500 mW when the duty factor is 0.5. Furthermore, the experiment demonstrates high voltage gains and flexible controllability of an output voltage.