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LED Driver Basic Introduction

Jul 01, 2019

LED Driver Basic Introduction


To do a good job of LED lighting products, the key lies in heat dissipation, driving power supply and light source, and heat dissipation is particularly important. The heat dissipation effect directly affects the quality of life of the lighting products, while the life of the driving power supply itself and the stability of the output current and voltage are on the product. The overall quality of life also has a large impact, and the light source is the core of the entire product.


1. What is the LED driver power supply?


The LED driving power source converts the power supply into a specific voltage and current to drive the LED light-emitting voltage converter. Usually, the input of the LED driving power source includes high-voltage power frequency AC (ie, mains), low-voltage DC, high-voltage DC, low-voltage high-frequency. AC (such as the output of an electronic transformer). The output of the LED driver is mostly a constant current source that changes the voltage as the LED's forward voltage drop changes. The core components of the LED power supply include a switch controller, an inductor, a switching component (MOSfet), a feedback resistor, an input filter component, an output filter component, and the like. According to different occasions, there must be input overvoltage protection circuit, input undervoltage protection circuit, LED open circuit protection, overcurrent protection and other circuits.



2, LED drive power features


(1) High reliability Especially like the driving power of LED street lamps, it is installed at high altitude, it is inconvenient to maintain, and the maintenance cost is also large.


(2) High efficiency LED is an energy-saving product, and the efficiency of driving the power supply is high. It is very important to dissipate heat from the power supply installed in the fixture. The power source has high efficiency, its power consumption is small, and the heat generated in the lamp is small, which reduces the temperature rise of the lamp. It is beneficial to delay the light decay of LEDs.



(3) Driving method


There are two types of traffic: one is a constant voltage source for multiple constant current sources, and each constant current source supplies power to each LED separately. In this way, the combination is flexible, and all the LED faults do not affect the work of other LEDs, but the cost will be slightly higher. The other is direct constant current power supply, which is the driving mode adopted by “Zhongke Huibao”. LEDs are operated in series or in parallel. Its advantage is that the cost is lower, but the flexibility is poor, and it is necessary to solve a certain LED failure without affecting the operation of other LEDs.



(4) Surge protection


The ability of LEDs to withstand surges is relatively poor, especially against reverse voltage capability. It is also important to strengthen protection in this area. Some LED lights are installed outdoors, such as LED street lights. Due to the start of the grid load and the induction of lightning strikes, various surges will be invaded from the grid system, and some surges will cause LED damage. Therefore, the analysis of the "Zhongke Huibao" drive power supply should have a certain lack of surge protection, and as the power supply and lamps are frequently replaced, the LED drive power supply should have the ability to suppress the intrusion of surges and protect the LED from damage.



(5) Protection function


In addition to the conventional protection function, the power supply preferably increases the LED temperature negative feedback in the constant current output to prevent the LED temperature from being too high; it must meet the safety and electromagnetic compatibility requirements.