Application analysis of LED power supply in LED lamps

Because LED has the advantages of environmental protection, long service life, high photoelectric efficiency (the light efficiency has reached 100LM/W), has many advantages such as seismic, in recent years the rapid development of the industry, in the application of the theory, the service life of the LED in 100 thousand hours, but in the actual application process, some LED lighting designers to know the LED driver insufficient or improper selection or the pursuit of low cost, the LED lighting products greatly shortened life expectancy, LED lamp life of 2000 hours, or even lower, which results in the advantage of LED lamps can not play very well.

Due to the particularity of LED processing and manufacturing, the current and voltage characteristics of LED produced by different manufacturers and even the same manufacturer in the same batch of products have great individual differences. The high-power white 1W LED specifications for typical cases, in accordance with the law of change of the current and voltage of LED to do a brief description of the general 1W, light application forward voltage is about 3.0-3.6V, that is to say, when nominal 1W in LED through 350 ma current when the voltage across it may be 3.1V, may also be in the 3.2V or 3.5V may also be other values, in order to ensure the life of 1WLED, the general LED manufacturers recommend lamps factory with 350mA current to drive, when the forward current through the LED ends up to 350 Ma, LED forward voltage at both ends of the small increases, will make up the LED forward current greatly, so that the temperature of LED a linear increase, thus accelerating the LED decay, the LED life is shortened, or even seriously damage the LED. Due to the particularity of the voltage and current of the LED, the power supply of the drive LED is strict.

Constant current source driver is the best LED driving mode, the constant current source drive, without limiting resistor in series output circuit, LED current is not affected by external power supply voltage changes, the ambient temperature changes, and the impact of discrete LED parameters, so as to maintain a constant current, give full play to the excellent characteristics of LED.

The LED constant current power supply to the LED lamp power supply, the current power supply during the work will be automatic detection and control through the LED so don't worry too much current flows through the LED in the power of the moment, do not have to worry about the power load short circuit burned out.

Some manufacturers worry about power driven plate with electrolytic capacitor will affect the life of the power supply, is actually a misunderstanding, for example: if the choice of 105 degrees, high temperature electrolytic capacitor life for 8000 hours, according to current estimates of each electrolytic capacitor life is reduced by 10 degrees ", life is doubled, then it is working in 95 degree environment life for 16000 hours at work at 85 degrees under the environment of life for 32000 hours, at 75 degrees under the environment of working life is 64000 hours, if the working temperature is lower, then life will be longer! In view of this, as long as the use of high quality electrolytic capacitors on the power supply life is not affected.

There is also a little attention to LED lighting companies: as the LED will release a lot of heat in the process of work, so that the rapid increase in the junction temperature, the higher the LED power, the greater the heat effect. Increased LED chip temperature will lead to attenuation of light emitting diodes and electro-optical conversion efficiency, even when serious failure, according to the results of the experiments show that for every increase of 5 degrees Celsius LED its temperature, the flux decreased by 3%, so we must pay attention to the work of LED lamp radiating LED light source, LED light source heat dissipation area as far as possible to increase their where possible, as far as possible to reduce the working temperature of LED itself, if conditions permit, the best can separate the power part and the light source part, the pursuit of small volume and ignore the lamps and power working temperature is not desirable.