iW3629

iW3629 Two-Stage, Flickerless™ Digital Off-Line LED Driver with High PF and Low THD 1 Description The iW3629 is a high-performance AC/DC off-line digital power supply controller for LED luminaires up to 120W or above. The two-stage design combines high power factor (PF > 0.95), low total harmonic distortion (THD <10%) and negligible line frequency ripple (< 5%) to make the iW3629 ideal for high-power non-dimmable LED lamps and luminaires. The two-stage approach allows the first-stage boost converter to convert the rectified AC voltage (90VAC to 277VAC) to an intermediate voltage while correcting for power factor. The second-stage flyback converter then provides the constant current regulation to the LEDs. The combination of an active start-up circuit and fast yet smooth soft-start for both boost and flyback stages results in a start-up time (AC plug-in to 90% of set LED current) of less than a half second and fast power factor settling time. The iW3629 operates in a quasi-resonant mo...