ML4833

Complete power factor correction and dimming ballast control in one IC
Low distortion, high efficiency continuous boost, peak current sensing PFC section
Programmable start scenario for rapid or instant start lamps
Lamp current feedback for dimming control
Variable frequency dimming and starting
Programmable restart for lamp out condition to reduce ballast heating
Internal over-temperature shutdown replaces external heat sensor
PFC overvoltage comparator eliminates output "runaway" due to load removal
Low start-up current <0.5mA
Power reduction pin for end of life and GFI detectors

The ML4833 is a complete solution for a dimmable or a non-dimmable, high power factor, high efficiency electronic ballast. The BiCMOS ML4833 contains controllers for "boost" type power factor correction as well as for a dimming ballast. The ML4833 was designed to minimize the number of external components required to build an electronic ballast.

The PFC circuit of ML4833 uses a new, simple PFC topology which requires only one loop for compensation. This system produces a power factor of better than 0.99 with low input current THD. An overvoltage protection comparator inhibits the PFC section in the event of a lamp out or lamp failure condition.

The ballast controller section of ML4833 provides for programmable starting sequence with individually adjustable preheat and lamp out-of-socket interrupt times. The IC controls lamp output power through feedback. The ML4833 provides a power down input which reduces power to the lamp, for GFI, end of life, etc.