The Power LED Driver is dedicated for optimum performance to drive Power LED's. FX5959 is a complete system solution for all Power LED's with high current for e.g. > 300mA. The driver provides a constant current without exceeding the applicable LED voltage to ensure the specified LED load life time. The integrated Current Source provides flexibility of utilizing various battery configurations and chemistries such as NiCd, NiMH, or Li+ with input voltage range of 2.5v to 6v. An additional flexibility is provided by using external resistors to adapt to various voltage input levels and LED configurations. For ultra-high efficiency, the Power LED Driver is designed to operate in synchronous rectified PWM mode under full load while transforming into externally controlled pulse-skipping mode (PSM) under light load (e.g. for LED's with 20 to 200mA).