XT2114A is a high-power factor, high constant current precision and high efficiency primary side controller, which build in input AC line over voltage/under voltage protection and output current foldback under high ambient temperature. It supports both isolated fly-back and non-isolated Buck-Boost application. XT2114A introduces advanced primary constant current control technology and then the secondary output current is controlled well by primary side information wit out extra optocoupler, which simplify the secondary side control circuit greatly. The unique four levels output current foldback value under high ambient temperature is selectable only by one external resistor. XT2114A operates in Quasi resonant mode, which can reduce the switching loss of MOSFET. With optimized valley detection and line voltage compensation circuit, it ensures the output current accuracy under the universal input AC voltage range.