Efficient GaN-based hybrid DC-DC converter with simple and low-cost bootstrap gate drivers for LED lighting applications

Abstract

This paper presents a 40 V-to-8 V GaN-based hybrid DC-DC converter design using 5-to-1 Dickson switched-capacitor structure. The converter, supporting a wide range of output voltage up to the input voltage, is suitable for LED driver applications in smart homes. We propose simplified and minimal gate driving schemes for N level Dickson switched-capacitor scheme where the number of gate driver chips is limited to only 3 that leads to a substantial decrease of circuit board size and cost. Detailed loss analysis, considering soft charging effect from the output inductor, is presented. To examine the effectiveness of the proposed scheme, a GaN-based hybrid DC-DC converter prototype is implemented and experimentally verified using commercial LED lamps. The circuit offers a peak efficiency of over 94% and a peak current of ∼1A at an output range from 4 V to 28 V from a 40 V input for the simplified gate driving scheme. The converter prototype using the minimal gate driving scheme achieves a peak efficiency of ∼93% with ∼43% reduction in gate driver chips and ∼35% reduction in gate driver area, promising a compact and low-cost solution for future LED drivers.