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The principle of LED dimmer

Writer:www.turnmax-tech.comSource:东莞市腾茂电子有限公司 Date:2016-11-10
The project content
There are three kinds of LED dimmer principle
1. The Pulse Width control dimmer (Pulse Width Modulation, PWM)
Square wave digitization, the power supply and control the square wave duty ratio, so as to achieve the goal of control current.
2. The constant current power supply regulation
Using linear technology can easily adjust the size of the current simulation.
3. The group control
Will be more than LED group, with simple group control.
The above 1.2. Two methods can be made no adjustable resistance knob control. Due to the PWM module technical maturity, and lower cost. It is difficult to judge from the aspects of price is to use what way the curtains. However, adjustable resistance itself is not a very reliable components. Often because of dirt to enter or not manufacturing process, the operating adjustable resistance with instantaneous jump empty fault, then the light will flash. This way of flashing in PWM situation is not obvious, in the case of using linear current technical regulation is obvious.
, no matter how to control current can be changed to touch type button Switch, Tact Switch) or a separate packet Switch (e.g., grouping, remote controller) to control the lights. The quality is reliable, service life is much longer. It is necessary to do with adjustable resistance of lighting, suggest using high quality of the adjustable resistance (usually a few yuan to 10 yuan).
Whether LED by buck, boost, buck/boost or linear regulator driven, connect each drive circuit is the most common thread need to control the light output. Today only a very few applications need only simple function, and off the vast majority of all need to fine tune the luminosity from 0 ~ 100%. At present, in view of the photometric control aspect, the main two kinds of solution for linear control the LED current (analog dimming) or imperceptible to the naked eye under high frequency, let drive current to the target current value from 0 to switch back and forth between (digital dimming). Using pulse width modulation (PWM) to set the cycle and the cycle time is probably the most simple to realize digital dimming method, the reason is that the same technology can be used to control most of the switching converter.
PWM adjustable light energy deployment of accurate color
In general, analog dimming is relatively easy to implement, it is because the LED driver output current and the control voltage is proportional to the change, and simulate the dimming will not cause additional electromagnetic compatibility (EMC)/potential frequency electromagnetic interference (EMI) problem. However, most design USES PWM dimming of reason is based on the fundamental properties of the leds, namely the emissive displacement is with the drive current is proportional to the size of the average (figure 1). For monochrome leds, mainly changes the wavelength of light waves, in respect of white LED, the change is relatively color temperature (CCT). For people to the naked eye, it is difficult to detect red, green or blue LED in the nanometer wavelength change, especially when the intensity of light is also changing, but the white light color temperature change is more easily detected. Most of the white LED is contained a photon can emit blue light spectrum of the wafer, the photons in hitting a phosphor coating will emit photons of various kinds of visible light range. In smaller power flow, phosphor will become dominant and make the light to yellow; In large electrical flow, leds emit blue light is more, make to blue light, at the same time also can produce higher CCTS. To use more than one application of white LED, CCTS difference between two adjacent LED will be very obvious, and visual unpleasant, this concept can be further extended to multiple monochromatic light in LED light mixed together. Once more than a light source, any CCTS differences in between them will feel dazzling.

TypeInfo: Corporate News

Keywords for the information:LED dimming power supply  The principle of LED dimmer