ELECTRONIC BALLAST IC WITH ADJUSTABLE PREHEAT TIME AND MINIMUM FREQUENCY FOR HOT FLUORESCENT LAMP

A novel ballast control IC is presented, which fully satisfies specific needs of hot cathode fluorescent lamp and significantly simplifies the external circuit design with the great reliability, generality and practicability. Integrated with a simple multi-frequency oscillator, the IC obtains adjustable preheat-time by controlling frequency changing rate with an external capacitor, and adjusts the minimum frequency by controlling minimum charging current with an external resistor. And a steady dead-time can also be achieved. Based on 0.5 mu m BCD process, the HSPICE simulation was done with 14V voltage supply. While a 1 mu F capacitor and a 100 k Omega resistor are utilized in the external circuit, this IC gives out a preheating frequency up to 175 kHz and the minimum working frequency is 75 kHz. A high frequency preheating time of 1s and a steady dead-time of 2 mu S can also be achieved.