A study on the power LEDs drive circuit design with asymmetrical half-bridge resonant converter

Recently white light-emitting diode (LED) has very attractive attention as a backlight for LCD display and lighting sources. The series-parallel connected LEDs must be driven from a current source because their forward voltage varies, as a result the brightness changes depending on the forward current increases. In this paper, the suitable LED driving system is proposed for LED lighting sources. The driving system is consist of high power factor correction circuit and isolated constant current DC-DC converter with high efficiency.