mp4026初级侧控制，离线式LED有源PFC控制器

　　The MP4026 is a primary-side-control， offline LED controller that achieves high-power factor and accurate LED current for isolated， singlepower-stage lighting applications in a tiny TSOT23-6 package. It is the next generation of the successful MP4021A. The proprietary realcurrent-control method accurately controls LED current from primary-side information with good line and load regulation. The primary-side-control eliminates the secondary-side feedback components and the opto-coupler to significantly simplify LED-lighting-system design. The MP4026 integrates power-factor correction and works in valley switching mode to reduce MOSFET switching losses. The MP4026’s multiple protection features greatly enhance system reliability and safety. These features include over-voltage protection， short-circuit protection， primary-side over-current protection， brown out protection， cycle-by-cycle current limiting， VCC under-voltage lockout， and auto-restart over-temperature protection.