LED is abbreviated as light-emitting diode. Because it has many advantages such as environmental protection, long life, high photoelectric efficiency (current light efficiency has reached 100LM/W), and earthquake resistance, it has been rapidly developed in various industries in recent years. In theory, the service life of LED is About 100,000 hours, but in the actual application process, some LED lamp designers have insufficient understanding of the LED drive power supply or choose inappropriate or blindly pursue low cost. As a result, the life of LED lamp products is greatly shortened, and the life of poor LED lamps is less than 2000 hours , Some are even lower, as a result, the advantages of LED lamps and lanterns can not be played well.

Due to the particularity of LED processing and manufacturing, the current and voltage characteristics of LEDs produced by different manufacturers or even the same manufacturer in the same batch of products have large individual differences. Taking the typical specifications of high-power 1W white LED as an example, a brief description will be made according to the current and voltage changes of the LED. Generally, the forward voltage of 1W white light is about 3.0-3.6V, that is to say, when the standard is called 1W LED When a current of 350 mA flows, the voltage across it may be 3.1V, 3.2V or 3.5V or other values. In order to ensure the life of 1WLED, general LED manufacturers recommend that the lamp factory use 350mA to go Driving, when the forward current through the LED reaches 350 mA, the small increase in the forward voltage across the LED will cause the LED forward current to rise greatly, causing the LED temperature to rise linearly, thereby accelerating the LED light decay , To shorten the life of the LED, and even burn out the LED in severe cases. Due to the particularity of the voltage and current changes of LEDs, strict requirements are imposed on the power supply for driving LEDs.

Constant current source driving is the best LED driving method. It adopts constant current source driving without series current limiting resistor in the output circuit. The current flowing on the LED is also not affected by external power supply voltage changes, ambient temperature changes, and discrete LED parameters. Influence, so as to keep the current constant and give full play to the various excellent characteristics of LED.

The LED constant current power supply is used to supply power to the LED lamps. Since the current flowing through the LED is automatically detected and controlled during the power supply operation, there is no need to worry about excessive current flowing through the LED at the moment of power-on, and there is no need to worry about load short-circuit burning Bad power supply.

Some manufacturers worry that the use of electrolytic capacitors on the power supply drive board will affect the life of the power supply. In fact, it is a misunderstanding. For example: if you choose a high-temperature electrolytic capacitor with a temperature of 105 degrees and a life of 8000 hours, according to the commonly used method of estimating the life of electrolytic capacitors, every 10 degrees reduction , Double the life expectancy", then it has a working life of 16000 hours in a 95-degree environment, 32,000 hours in an 85-degree environment, and 64000 hours in a 75-degree environment. If the actual working temperature is lower, Then the lifespan will be longer! From this point of view, as long as the use of high-quality electrolytic capacitors has no effect on the life of the driving power supply.

It is also worth noting the attention of LED lamps and lanterns companies: as LEDs emit a lot of heat during their work, the die junction temperature rises rapidly. The higher the LED power, the greater the heating effect. The increase in the temperature of the LED chip will lead to changes in the performance of the light-emitting device and the attenuation of the electro-optical conversion efficiency. In severe cases, it may even fail. According to experimental tests, every time the temperature of the LED rises by 5 degrees Celsius, the luminous flux drops by 3%. For heat dissipation of the light source itself, if possible, increase the heat dissipation area of the LED light source as much as possible, and reduce the working temperature of the LED itself. If conditions permit, it is best to separate the power supply part from the light source part and blindly pursue small size It is not advisable to ignore the working temperature of lamps and power supplies.