ML4835

July 2000 PRELIMINARY ML4835* Compact Fluorescent Electronic Dimming Ballast Controller GENERAL DESCRIPTION The ML4835 is a complete solution for a dimmable or a non-dimmable, high power factor, high efficiency electronic ballast especially tailored for a compact fluorescent lamp (CFL). The Bi-CMOS ML4835 contains controllers for “boost” type power factor correction as well as for a dimming ballast with end-of-lamp life detection. The PFC circuits uses a new , simple PFC topology which requires only one loop for compensation. In addition, this PFC can be used with either peak- or average-current mode. This system produces a power factor of better than 0.99 with low input current THD. The ballast controller section provides for programmable starting sequence with individual adjustable preheat and lamp out-of-socket interrupt times. The ML4835 provides a shut down for both PFC and ballast controllers in the event of end-of-life for the CFL. FEATURES s s s s s s s s s s Power detect for end-of-lamp-life detection Low distortion , high efficiency continuous boost, peak or average current sensing PFC section Leading- and trailing-edge synchronization between PFC and ballast One to one frequency operation between PFC and ballast Programmable start scenario for rapid/instant start lamps Triple frequency control network for dimming or starting to handle various lamp sizes Programmable restart for lamp out condition to reduce ballast heating. Internal over-temperature shutdown PFC ...