Improvement in efficiency of LED lighting system based on reduction of voltage across MOSFET

In this paper, a LED dimming circuit powered by the KY converter, which is named after the first capitals of two authors' names: Kuo-Ing Hwu and Yeu-Torng Yau, is presented, which is controlled based on the field-programmable gate array (FPGA). By a given dimming command and the proposed maximum gate voltage detector, the voltage across the MOSFET in the linear current regulator can be reduced so as to upgrade the efficiency of the overall system. Aside from this, each LED string takes level dimming, and is powered by the KY converter, which has an output inductor and hence upgrades the life of the output capacitor. Furthermore, via some experimental results, the efficiency based on the proposed control method is higher than that based on the traditional control one.