Semi-valley switching method for buck LED driver to increase its efficiency and performance

Valley switching is one of the most efficient methods to decrease the switching losses in DC/DC converters. It uses a resonance between the converter's inductor and parasitic output capacitance of a metal–oxide–semiconductor field-effect transistor. In this study, the drawbacks of the valley switching in buck light-emitting-diode (LED) drivers are investigated. It shows that in spite of decreasing the switching losses, the valley switching method reduces its efficiency in some conditions. Also, it is clarified that the valley switching method not only causes current fluctuation in boost power factor correction converters but also malfunctions the buck LED drivers' performance. In this study, a semi-valley switching and its implementation are introduced to solve these problems. In general, it is shown that the proposed method improves both the efficiency and the performance of the buck LED driver, simultaneously. The methodologies are implemented in an experimental prototype to verify the proposed method.