Controlling LEDs Part 1

Ten years ago, many people didn’t even know what an LED was. Today, they’re the new hot item on the shelves – and everyone wants to use them. Often, designers do not know how to control LEDs or they have had negative experiences working with them. This articles will provide a brief overview of what an LED is and how to use LEDs for general illumination applications and the advantages and limitations of doing so. It will also go into detail about why you should consider dimming LEDs and what questions need to be answered in order to dim LEDs properly to meet your expectations. The overall goal of this article is to make you more comfortable with using LEDs
on your projects.


What is an LED?


A Light Emitting Diode (LED) is an electronic device that produces light when an electrical current is passed through it. The wavelength (or color) of light that is emitted is dependent on the materials from which the LED is made. LEDs are available in many colors, including red, blue, amber, green, and near-UV colors, with lumen outputs ranging from 10 lumens to 200 lumens. The LEDs used predominantly in general illumination applications are “Phosphor Converted Blue” LEDs, which are blue LEDs that have a layer of yellow phosphor placed over the LED. The phosphor absorbs some of the blue light, and emits yellow light. When the unabsorbed blue light mixes with the yellow light it creates what your eye perceives as “white” light.

IMAGE OF DIFFERENT TYPES OF LEDS.

From Controlling_LEDs by LUTRON