Multi-frequency oscillator with dead time in electronic ballast

Abstract

The invention discloses a multi-frequency oscillator with dead time in electronic ballast, and mainly solves the problems that a preheating type fluorescent lamp is not preheated or preheating time isinsufficient, and the service life is short. The multi-frequency oscillator with the dead time in the electronic ballast comprises a reference current and mirror image circuit (1), a control voltagegenerating circuit (2), a minimum current generating circuit (3), a discharging current control circuit (4), a charging current control circuit (5), an oscillating circuit (6) and a dead logic circuit(7); the output of the control voltage generating circuit (2) is connected to the charging current control circuit (5) and generates gradually varied charging current, the minimum current generatingcircuit (3) generates minimum charging current, a frequency gradually varied clock signals are generated through the oscillating circuit (6), the output of the oscillating circuit (6) is connected tothe dead logic circuit (7), and high-and-low-end control signals with stable dead time are generated. The preheating type fluorescent lamp works normally, the service life of the lamp can further be prolonged, and the lighting effect is improved.

Description

technical field [0001] The invention belongs to the technical field of electronic circuits, and relates to an analog integrated circuit, in particular to a multi-frequency oscillator, which can be applied to electronic ballasts for preheating fluorescent lamps. Background technique [0002] Multi-frequency oscillators are widely used in electronic ballasts for preheating fluorescent lamps. By changing the oscillation frequency in different time periods, the preheating, ignition and normal lighting of fluorescent lamps can be realized. According to the characteristics of the preheating fluorescent lamp, its normal operation has three stages: 1. When the lamp circuit is at a higher frequency point f ph 2. When the frequency gradually decreases and tends to the natural frequency point f of the LCC series resonant parallel load circuit 0 3. Finally, make the fluorescent lamp work at a constant frequency f run , normally emit light under rated power. [0003] figure 1 It is a...

AI Technical Summary

Problems solved by technology

[0007] 1. The circuit structure is complex and not easy to integrate;

[0008] 2. The minimum operating frequency generated by the circuit is fixed. If the resistance characteristics of the filament are changed, the light efficiency of the fluorescent lamp will be deteriorated;

[0009] 3. When applied to electronic ballast chips, the output signal of the circuit needs to pass through the high-end dead zone generating circuit to obtain the high-end control signal and the low-end dead zone generating circuit to obtain the low-end control signal, and these two dead zone generating circuits are due to Inconsistently affected by process deviation and ambient temperature, resulting in unstable dead time

If the dead time is too small, the switching tube in the external inverter circuit cannot meet the zero-voltage conversion conditions when it is turned on, thereby increasing heat loss and even damaging the switching tube.

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