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 1200 V 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, over- and undervoltage protection, temperature-protection, low temperature detection for increased preheating time, dimming or power control, by changing the supply voltage up to 50%, 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 factor 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 1200 V DMOS transistor, and only 5 pins, gives the possibility of low cost solutions in the future, e.g. with new power technologies like the Cool-Mos technology.