LED Lighting Adopts A Driving Strategy

- Feb 12, 2021-

How to choose a suitable LED drive power wisely is a problem that every engineer is concerned about. I have compiled the opinions of netizens in the forum for your reference.

According to the characteristics of the power grid, the requirements of LED characteristics and related LED products, three general principles should be followed when considering the selection of LED driving power:

1. According to the characteristics of LED current and voltage, it is ideal to drive. It can avoid current changes caused by the change of the LED forward voltage, and at the same time the constant current makes the brightness of the LED stable.

2. In addition, the luminous flux of the LED is inversely proportional to the temperature, so it is necessary to minimize the constant current heating of the power supply and a well-designed heat dissipation system during use. Thereby reducing the working temperature of the LED.

3. In order to ensure the overall life of the LED, the temperature of the LED must be controlled within a certain range.

The following are ten considerations for choosing LED drive power:

1. High reliability: LED products mainly have LED chips

It is composed of power supply, heat dissipation shell, control circuit, etc. The quality of the LED power supply directly affects the quality of the product. Especially LED street light products are inconvenient and expensive to maintain because they are installed at high altitude.

2. High efficiency: LED is an energy-saving product, and the driving power supply must meet the energy-saving requirements. Especially the structure of the power supply installed in the lamp is particularly important. Because the luminous efficiency of the LED decreases as the temperature of the LED increases. The efficiency of the power supply is high, 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 LED.

3. Constant current drive mode: In order to match the VI characteristics of the LED, the LED power supply must use a constant current drive mode.

4. Surge protection: LED has poor impact resistance, so it is necessary to strengthen this protection. Especially some products installed outdoors, due to the start of the grid load and thunder. Therefore, the LED drive power supply must have the ability to suppress the intrusion of surges and protect the LED from damage.

5. Temperature protection function: In addition to the conventional protection function of the power supply, it is better to add negative feedback of the temperature of the LED chip to the constant current output to prevent the temperature of the PN section of the LED chip from being too high.

6. LED power supply life: the life of the driving power supply is matched with the life of the LED chip as much as possible.

7. Working environment: Due to the different environments of various places, the environment of the working place of the LED lamps should be considered, such as temperature, humidity, installation location, etc. Considering the working mode of the power supply, if the soft start circuit is not added, the output will have a voltage spike at the moment of power-on. In order to better protect the LED, it is necessary to add a soft start circuit. This is a key factor in the stability of the drive power supply.

8. The power factor of the LED drive power supply: the power factor varies greatly when the same product is used in a large area, which is also a key point for energy-saving products.

9. It is best to use an electrolytic capacitor design for the LED drive power supply: Under normal use conditions, electrolytic capacitors are the shortest life-span devices among the components on the circuit board. Generally, the lifespan is about 5000 hours at the rated temperature. It may only be 2000 hours. At present, the entire social environment is pursuing unprincipled reduction of product manufacturing costs. Therefore, when a relatively high price is not obtained, there is little chance of choosing good materials. When the heat dissipation condition is good, the life of the LED reaches 30,000-50,000 hours is no problem. In order to match the life of the driving source and the light source, the driving source without electrolytic capacitor is a better choice. We choose to design a non-electrolytic capacitor driving source in the underground explosion-proof LED roadway lamp, and the effect is very good.

10. Set current limit: When the drive source drives multiple LED dies, pay attention to the series-parallel relationship between each channel. In addition to constant current, set current limit to prevent accidents.

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