Such as it has environmental protection, long service life, photoelectric conversion efficiency of high (currently luminous efficiency has reached 100lm / W), seismic and many other advantages, in recent years in various industrial applications can be rapid development, theory, the service life of the LED at about 10, 000 hours, but in practical application process, some LED lamp design personnel of LED driving power insufficient understanding or using improper or blindly pursue low cost, the LED lighting products greatly shortened life expectancy, poor LED lamp life of less than 2000 hours, and some are even lower. As a result, the advantages of LED lamps and lanterns not play to the good.
Due to the particularity of LED manufacturing, the current and voltage characteristics of different manufacturers and even the same manufacturer in the same batch of products have great individual differences in LED's current and voltage characteristics. 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. Because of the particularity of the voltage and current of LED, the power of driving LED is strictly required.
LED drive power is the key to LED lamps, it is like a person's heart, to produce high-quality, used for lighting LED lamps must give up the constant pressure way to drive LED.
1.7-2.5V in 2.7-4V in fewer or now many high power LED packaging factory will be many stars single led by parallel and series of the sealed together produce a single 20W, 30W 50W and 100W even more high power LED, in spite of the package of the single led the strict selection and pairing, but due to internal has dozens of stars, many hundreds of single body led, the packaging of high power LED products in the voltage and current still have great differences, and compared to a single LED (usually a single white, green, blue working voltage, a single red light, yellow light, orange light voltage) parameters difference more big! (reminded of the LED lighting has just launched the LED light source packaging quality can not be ignored)
At both ends of the resistance, so that the many manufacturers of LED lighting products (for example, guardrail, lamp, projection lamp, courtyard lamp, etc.), the resistance and capacitance voltage reduction, and then with a zener diode voltage to the LED power supply LED driver there is a great defect. The first is low efficiency in a dropping resistor consume a large amount of electric energy, and even may exceed led the consumption of electrical energy, and can not provide high current drive, because the current is consumed in the step-down power is big, cannot be guaranteed through the LED current is not more than the normal work requirements, product design will reduce the LED voltage to supply power to drive, this is at the expense of LED brightness for the price. The resistance and capacitance voltage reduction method is used to drive the LED, the brightness of the LED can not be stable, when the power supply voltage is low, the brightness of the LED becomes dark, the power supply voltage is high, and the brightness of the LED becomes brighter. Of course, resistance, capacitive pressure reduction way to drive the LED's biggest advantage is low cost, so there are still part of the LED Lighting Companies in this way.
Some manufacturers, in order to reduce the cost of products, the use of constant pressure to drive LED, also brought the batch production of each LED luminous brightness is not uniform, LED can not work in the best state, and a series of problems