Fluorescent lamp starting and scanning control circuit and control method thereof

Abstract

The invention relates to a fluorescent lamp starting and scanning control circuit and a control method thereof. The fluorescent lamp starting and scanning control circuit comprises an oscillator, a counter and a digital-analog converter which are sequentially connected in series, wherein the output end of the oscillator is connected with the input end of the oscillator, and the output end of the digital-analog converter outputs a feedback signal to the oscillator. The oscillator comprises a first current supply, a first switch, a second switch and a second current supply which are sequentially connected in series and also comprises an oscillating capacitor, a first comparator, a second comparator and a logical circuit, wherein one end of the oscillating capacitor is connected between the first switch and the second switch, and the other end of the oscillating capacitor is grounded. In the invention, a digitized method is utilized to control and realize the processes of high-frequency preheating, scanning ignition, low-frequency working, and the like needed by starting a fluorescent lamp. Otherwise, the area of a chip pin or a chip in an electronic ballast is saved, and the protection function of the fluorescent lamp can be more conveniently developed.

Description

technical field [0001] The invention relates to an integrated circuit, in particular to a fluorescent lamp start-up sweep control circuit and a control method in an electronic ballast. Background technique [0002] As we all know, the driving of fluorescent lamps relies on electronic ballasts. Nowadays, in order to achieve high-efficiency and energy-saving lighting, electronic ballasts usually need to convert power frequency signals into high-frequency square wave signals to drive fluorescent lamp load circuits. Start-up needs to go through three stages of preheating, ignition and normal operation, so the electronic ballast needs to provide high-frequency, sweep-frequency, and low-frequency square wave signals for the three processes of fluorescent lamp start-up respectively, as the control drive in the electronic ballast In the prior art, the circuit is realized by a voltage-controlled oscillator, that is, a voltage-controlled oscillator is used to generate the above-mentio...

AI Technical Summary

Problems solved by technology

[0019] However, by figure 1 , figure 2 It can be seen that using a voltage-controlled oscillator to generate a clock signal to realize the function of frequency sweep ignition must first generate a sweep voltage from high to low. This voltage is usually generated by charging and discharging a large capacitor, thereby increasing The pins of the chip in the electronic ballast are increased or the area of ​​the chip is increased, so the existing technology can no longer meet the needs of users

Images