Tuesday, April 7, 2015

Types of LEDs

Light emitting diode is a pn-junction diode that emits light when activated. These diodes come in different varieties and are used for various purposes. From first look all the LEDs look and feel alike, however there are some specific features which distinguish them from each other. A brief classification of LEDs is as follows which will help you to find the right LED.

Miniature: Miniature LEDs are small in size ranging from 2mm to 8mm. These types of LEDs have current range from 1mA to above 20mA. 

Miniature LEDs are further classified in three types:

  • Low-current: For 2mA at 2V
  • Standard: For 20mA i.e. 1.9-2.1V(Red, Orange  and Yellow), 3.0-3.4 V(Green and Blue) and 2.9-4.2 V(Violet, Pink and White) 
  • Ultra-high-output: 20mA at 2V-5V

Mid-range: These medium power LEDs are used when an output of just tens of lumens are needed. These LEDs are generally used in emergency lighting and automobile tail-lights. 

High-power: High output LEDs are capable of emitting over a thousand lumens.

AC LED: These LEDs were developed by Seoul Semiconductor. AC LEDs can be directly connected to normal power supply as they don’t need any driver like normal LEDs. 

Flashing: Flashing LEDs contain an integrated multi-vibrator circuit that causes the LED to flash for typical period of one second. Most of the Flashing LED’s emit only one colour, but more stylish ones can flash between multiple colours. 

Bi-colour LED: These types of LEDs contain two different LED emitters which help in producing two different colours.

Tri-colour/ RGB:  In these types of LEDs three different emitters are connected in one case in such a way that they can be controlled separately.

Features which make LED a better option compared to halogen and incandescent: 

Efficiency: Unlike fluorescent light bulbs or tube, efficiency of LED lighting fixtures is not affected by shape and size. 

Colour and Size: LEDs don’t use any colour filter to emit the light of an intended colour. LEDs are available in different sizes and can be used of variety of purposes. 

Lifetime: They have a quite extensive functional life.