ML4831

JULY 2000 ML4831* Electronic Ballast Controller GENERAL DESCRIPTION The ML4831 is a complete solution for a dimmable, high power factor, high efficiency electronic ballast. Contained in the ML4831 are controllers for “boost” type power factor correction as well as for a dimming ballast. The Power factor circuit uses the average current sensing method with a gain modulator and over-voltage protection. This system produces power factors of better than 0.99 with low input current THD at > 95% efficiency. Special care has been taken in the design of the ML4831 to increase system noise immunity by using a high amplitude oscillator, and a current fed multiplier. An over-voltage protection comparator inhibits the PFC section in the event of a lamp out or lamp failure condition. The ballast section provides for programmable starting scenarios with programmable preheat and lamp out-ofsocket interrupt times. The IC controls lamp output through either frequency modulation using lamp current feedback. The ML4831 is designed using Micro Linear‘s SemiStandard tile array technology. Customized versions of this IC, optimized to specific ballast architectures can be made available. Contact Micro Linear or an authorized representative for more information. FEATURES s Complete Power Factor Correction and Dimming Ballast Control on one IC Low Distortion, High Efficiency Continuous Boost, Average Current sensing PFC section Programmable Start Scenario for Rapid or Instant Start Lamps Lamp Curr...