Light-emitting diode ( LED ) technology has been available for about half a century. A light-emitting diode is a semiconductor device that emits light when a voltage deviation occurs. Due to its low power and low voltage operation, this technology is quickly applied to the status indication of various electronic devices. The lifetime of LED technology is usually very long, typically up to 10 years, far longer than other traditional lighting technologies (such as incandescent tubes and fluorescent tubes). This makes it very desirable to apply LED technology to a wider range of lighting applications.
New technologies that have recently emerged have enabled LEDs to achieve higher power levels. LEDs can reach a level of one watt, and some even up to 5 watts, with 18-44 lumens per watt. This type of LED device is called a high-brightness LED (HB-LED). Due to significant improvements in efficiency, HB-LEDs are rapidly being used in a variety of lighting applications.
Here are some examples of these applications:
traffic light
Background lighting device for flat display device
flash
Home lighting
HB-LEDs have a non-linear IV characteristic, very similar to a diode. HB-LEDs can only be illuminated when the DC is unidirectionally delivered to the device, commonly referred to as forward current IF. The voltage drop across the HB-LED is called the forward voltage VF. For the HB-LED to achieve maximum brightness, the forward current through the HB-LED must be kept constant. In a typical 1W HB-LED, the forward current needs to be kept at about 350mA, and the corresponding forward voltage is about 3.4V, and the HB-LED can reach its maximum brightness.
The forward current IF has a very close relationship with the forward voltage VF, and a small change in the VF causes a large change in the IF. The ideal power source for HB-LED drives is a constant power source. In practice, constant current is usually achieved by a closed loop current controlled DC-DC converter. There are many DC-DC converter solutions based on independent analog components and relatively low cost. However, microcontroller-based (MCU)-based solutions offer greater flexibility in system design. In addition to general lighting, this controller provides enough processing power for the final application to support additional features. Therefore it still has a great appeal.
Some of the advantages of MCU-based design are as follows:
(1) Light brightness adjustment and flicker can be easily achieved with the MCU software without adding additional components to the system.
(2) Different power or different brands of HB-LEDs have different characteristics, and the MCU can be programmed by software to meet different driving requirements. In this case, lighting manufacturers can reduce the type of inventory and simplify logistics processing.
(3) Many MCUs have chip flash memory that can be used for data storage in applications. For example, when implementing the light brightness control function, the chip flash memory can be used to save the brightness level. The last brightness level is automatically restored each time the light is turned on.
(4) In addition to lighting, the MCU can handle several functions, such as different types of connection standards (such as Zigbee, RS232, LIN, etc.) can also be easily implemented through the MCU chip module.
We custom Etching Cutting Die, Etching Metal Crafts, Etching Eyeglass Frames, Etching Plate Heat Exchanger Sheet with drawings provided by customers. We are equipped with professional metal etching equipment and exposure development equipment. The raw material we more use for these products is stainless-steel, brass, titanium and titanium-palladium. We can guarantee that our half etching plate heat exchanger sheet have straight surface line, and have no burr, high product accuracy.
Etching Cutting Die,Etching Metal Crafts,Etching Eyeglass Frames,Etching Plate Heat Exchanger Sheet
SHAOXING HUALI ELECTRONICS CO., LTD. , https://www.cnsxhuali.com