High efficiency and power density GaN-based LED driver

LED lighting is becoming more attractive and popular due to its high efficiency, long lifetime, instant brightness and ability to dim. But LEDs are powered by DC, which requires a rectifier to allow it to run off the AC utility grid. These converters must have small form factors and operate in high ambient temperatures due to the close proximity of the LED light. Gallium Nitride (GaN) based switched mode power supplies have the ability to increase switching frequencies to allow for form factors small enough to enable new applications with stricter space requirements. But to achieve this size reduction, the switching frequency must operate in the megahertz range, which requires soft switching techniques to achieve acceptable performance. A small and simple analog hysteresis-controlled valley-switched floating buck converter is proposed to solve these problems. This solution has a minimal component count while maintaining similar performance to existing solutions. A 20W prototype is built to verify the performance of the converter, which is measured to have a size reduction of 1.87× of the power stage when compared to an existing commercial product while achieving an efficiency of 91.2%, an input current THD of 15.9% and PF of 0.976.