Dimming control circuit and control method of led lamp under low brightness

Abstract

The invention relates to a dimming control circuit and a control method of an LED lamp under low brightness. The dimming control circuit includes triode Q1, triode Q2 and dimming driver. The base of triode Q1 is connected to the positive pole of the dimming driver through resistor R1 and connected to the negative pole of the dimming driver through resistor R2. The collector and emitter of transistor Q1 The poles are respectively connected to the positive and negative poles of the dimming driver, the collector of the transistor Q1 is connected to the base of the transistor Q2, the collector and emitter of the transistor Q2 are respectively connected to the positive and negative poles of the dimming driver, the collector, The emitter is also connected to the positive pole and the negative pole of the LED lamp respectively. When the output current I of the dimming driver is lower than the threshold current value I1 and higher than the threshold current value I2, both the transistor Q1 and the transistor Q2 are in a semi-conducting state. At this time, as the output current I of the dimming driver changes, the current The current passing through the LED lamp changes in a curve to realize the dimming effect of the LED lamp in a low current state.

Description

technical field [0001] The invention relates to an LED lamp drive circuit, in particular to a dimming control circuit and a control method for the LED lamp at low brightness. Background technique [0002] The use of thyristor dimmers to adjust the brightness of lamps has been applied to the dimming circuits of incandescent lamps and energy-saving lamps earlier, and it is also a dimming method widely used in LED lamp dimming solutions. Its working principle is: use the thyristor dimmer to adjust the conduction angle of each half-wave of the AC to change the sinusoidal waveform, change the effective value of the AC input current, and at the same time drive the output current to change accordingly, so as to realize the LED lamp. Dimming effect. However, there are many types of thyristor dimmers, and some thyristor dimmers will lose their dimming effect when the output current is adjusted below about 3%. The dimmer cannot control the output current, that is, it cannot achieve ...

AI Technical Summary

Problems solved by technology

However, there are many types of thyristor dimmers, and some thyristor dimmers will lose their dimming effect when the output current is adjusted below about 3%. The dimmer cannot control the output current, that is, the dimming effect cannot be achieved

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