Ten notes on selecting the LED drive power
How to choose the right LED driver power, is every engineer are concerned about the problem. According to the characteristics of the power grid, LED characteristics and related LED products, consider the choice of LED drive power to follow the three general principles:
1, according to the LED current and voltage characteristics, the ideal is to use constant current drive. It can avoid the LED forward voltage changes caused by current changes, while the constant current to LED brightness stability.
2, in addition, LED luminous flux and temperature is inversely proportional to, so the use of power should be minimized and the design of a good heat dissipation system. Thereby reducing the temperature of the LED's operation.
3, in order to ensure the overall life of the LED LED must be controlled in a certain range of temperature.
The following is the choice of LED drive power of the ten attention elements:
1, high reliability: LED products are mainly LED chips and power, cooling shell, control circuit and other components. LED power supply which directly affects the product is good or bad. In particular, LED street lamp products, due to installed at high altitude, maintenance is not convenient and costly.
2, LED drive power High efficiency: LED is energy-saving products, drive power also meet the energy requirements. Especially the power supply installed in the lamp structure, is particularly important. Because the LED luminous efficiency with the LED temperature increases and decreased. Power efficiency is high, its power consumption is small, the heat in the lamp is small, it will reduce the temperature rise of the lamp. Can delay the LED light failure favorable.
3, constant current drive mode: In order to meet the LED VI characteristics, so the LED power supply must use constant current drive mode.
4, surge protection: LED shock resistance is relatively poor, so to strengthen this protection. Especially some of the products installed in the outdoor, due to the start of the grid load and mine. So the LED drive power to suppress the surge of intrusion, the protection of the LED is not damaged capacity.
5, the temperature protection function: power supply in addition to the conventional protection function, the good current output to increase the LED chip temperature negative feedback, to prevent the LED chip PN section temperature is too high.
6, LED power life: drive the life of the great efforts to work with LED chip life together.
7, the working environment: due to the different parts of the local environment to focus on the work of LED lighting to consider the environment such as: temperature, humidity, installation location. Taking into account the power of the work, if not soft start circuit, power instantaneous, the output will have a voltage spike. For better protection of the LED, so need to add soft start circuit. This is a key factor driving the stability of the power supply.
8, LED drive power factor: the level of power factor in the same product when a large area of use is very different, which is energy-saving products to consider the key points.
9, LED drive power supply good use of electrolytic capacitor design: Under normal conditions of use electrolytic capacitors on the circuit board devices in the life of short devices, generally about 5000 hours at rated temperature life, good can be 10,000 hours, poor Probably only 2,000 hours. At present, the whole social environment in the pursuit of the principle of reducing the cost of manufacturing products, so, did not get a relatively high price, the choice of good material is not a great opportunity. LED life in the cooling conditions are better to reach 30000 - 50000 hours is no problem. To drive the source to match the life of the light source, the drive source is electrolytic capacitor is a better choice. We in the underground explosion-proof LED roadway lights in the design of non-electrolytic capacitor drive source effect is very good.
10, set the current limit: drive source in the drive multi-channel LED die attention to the relationship between each string in parallel, in addition to constant current but also set the current limit, to prevent accident occurred.
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