Application of single-transistor smart-power IC for fluorescent lamp ballast

A single-chip class-E converter was developed for fluorescent lamp ballasts. The IC is based on SIMOX technology and includes a 1200V DMOS transistor and a low voltage control part. It is applicable for compact and other fluorescent lamps up to 15 Watts. The functionality of the chip includes preheating, self-protection, temperature-protection, low temperature detection for increased preheating time, dimming or power control, by changing the supply voltage up to 50 per cent, and an input voltage independent power control of the lamp. The solution offers possibilities for applications with a reduced input charging capacitor for lower line voltages, or for bootstrap circuitry to achieve a high power facto r up to 0.9, universal input, voltage- and capacity-reduced charging capacitors, and inrush-current limiting. A smart-power IC with a low-voltage control part, a single 1200V DMOS transistor, and a number of only 5 pins, gives the possibility of low cost solutions in the future, e.g. wi th new po wer technologies like the Cool-MOS technology.