Correct selection of LED lighting driver power supply method and device configuration

Due to the LED energy saving, long service life, durable and flexible design, indoor and outdoor lighting leds are quickly replacing the incandescent lamp and fluorescent lamp. But choosing the right LED is only part of the design equations.

in order to make you solid-state lighting design to realize the comprehensive efficiency, durability and service life, you need to select a suitable power supply, put your application requirements and the use of leds to match. This article will provide some useful Suggestions for you, in the process of choosing power needs to be considered. Relevant background introduction once LED power supply voltage equal to or greater than the diode forward voltage drop ( Usually in 2 - The area of 3 v) And began to produce light by LED. Full brightness needed current owing to the different equipment, but for the 1 w leds ( Usually the smallest size in lighting applications) Usually is 350 ma. Unlike incandescent lamps, the LED is nonlinear devices. This means that once the power supply voltage than the diode forward voltage, through the current exponentially with the power supply voltage. Without some form of current regulation, LED chips will be expensive, monostable flash bulbs. In order to prevent this kind of situation, power must be in the right flow provide appropriate voltage. The simplest method is to select an output voltage is greater than the selected LED forward voltage of power supply, and a current limiting resistor specifies the maximum limit current to the LED manufacturers. The downside of this approach is that the LED lighting one of the main advantages of high efficiency will be affected by the current limiting device dissipation power. Another problem is that of the method of LED junction temperature affected the forward voltage. Due to the power supply output voltage is fixed, which in turn means that if current limiting device on both ends of the voltage change, current will change accordingly. Change of current will affect the amount of light emission, reduce the reliability of the leds. Best method is to use a constant current source driving leds. In this way, can set the current to the LED manufacturers specified maximum, to achieve maximum efficiency and reliability of brightness or achieve the desired accuracy, and can also in LED or ambient temperature changes to eliminate the influence of the junction temperature. In lighting applications, the use of a benefit is easy to change the brightness of LED. This can be done by changing the current through the LED, however, is less than its maximum current running leds will reduce the efficiency and could lead to a slight change of colors. Therefore, a better approach is to pulse current between zero and the maximum value to change the average light emission. As long as it is done in a high enough frequency, in order to avoid impulse is seen by the human eye as flash, this is the best way to realize the dimmer. Current pulse is usually at a fixed frequency, the ratio of zero and full current change. This is a pulse width modulation ( 脉宽调制) Methods. Choose the type of power supply for lighting applications choose power supply will be based on several factors. First, consider your application environment. Applications are for indoor or outdoor? The power do you need waterproof or need special IP rating? The power will be able to use the conduction convection cooling cooling or only use? Next, to define the overall power requirements. The individual may only need a small power of lamps and lanterns, but a complex system may need to provide hundreds of watts of power. In addition, also need other functions? Whether you need power supply, for example, in simple mode of constant voltage and constant current mode, the application need dimmer? Laws and regulations is important, then, now it's time to consider laws and regulations. Whether you need the whole system in a certain range of harmonic current run? Does it need to compliance with the safety standards of lighting, or ITE power is enough? In The Times of energy sensitive power how to effectively meet local or regional standards? Equally important, in some local government agencies to comply with a specific level of efficiency and power factor correction products offer discounts or other subsidies, the products are sold in these places? Also, know your design is in line with the standard requirements, it is also important, including closing any requirement of the power supply when the power consumption. Safety standards applicable to lighting system has a variety of criteria. Internationally, IEC61347 part 1 covers the general security requirements, lamps and lanterns control device and the second part (13 2) Section applies to the LED module power supply. America has UL8750, Europe has EN61347, are named after chapter IEC format.

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