Nowadays, there are various different types, shapes, sizes and colors of LEDs available. This is a direct and positive result of all the effort that has been put into the evolution and enhancement of semiconductor technology over the last couple of decades. You may only be familiar with the LED in your office lamp or those in various electronic and electrical devices and appliances throughout your home; but that is only scratching the surface really.
In the following post we will look at the many different types of LEDs and their uses.
Miniature LEDs (Chip, Nano & Pico LEDs)
Miniature LEDs are arguably the most common, are very small and are often available as a single color or shape. These are used in remote controls, calculators and mobile phones as indicators.
Thanks to their simple design and size, they can be placed onto a circuit board directly, without a device to cool or control heat. As a result, they are often utilized in technologically advanced and complex automated industries.
You will find that miniature LEDs can be split into 3 sub-types:
- Ultra-high output
All 3 of these vary in terms of the total wattage, voltage and current and their manufacturer. Also available are 12 and 5 volt varieties of miniature LEDs. These differ ever so slightly from standard miniatures though, as they use an appropriate series resistor so they can be connected directly to a high power source.
High Power LEDs
With improvements to the technology behind diodes, came High-Power LEDs. This category of LEDs is also often called high-output, as they produce a greater number of lumens than standard varieties. Interestingly, n actual fact, the high-powered chips in high output LEDs are capable of producing light consisting of 1,000s of lumens. High-Power (or output) LEDs can be split into various sub-types based on various parameters, such as:
As there is always a risk of these particular LEDs overheating, it is crucial that they are always connected to some kind of suitably heat-absorbent material, to encourage convection to cool them down. This not only keeps them working at an effective and efficient level, but stops them from burning out prematurely.
Regardless of what it is for, when purchasing a high-power LED of any kind, it is wise to consider heat control. There are certain temperature limits, in the same way there are maximum current limits. Even if a manufacturer claims they have designed the best high power LED ever, you should always check that there is sufficient balance between output and heat dissipation. When this balance is there, the LED’s lifespan and reliability is improved, which means money savings for you, eventually.
This very self-explanatory LED category can be split into numerous sub-types, including:
- RGB or Red Green Blue
- Bi-Color and Tri-Color
There are various different sizes and shapes of lighting LEDs (often called illuminators, LED bars or simply LED lamps). One of the most common is, of course, the Edison light bulb design which can be found in the best Candelabra bulbs and is very popular. As we’ve highlighted before, heat is a problem for LEDs. One way manufacturers are combating this issue is by utilizing a ceramic/aluminum body that features fins to expand the area where heat can escape from.
Depending on how a light is used and the manufacturer, the techniques for heat dissipation employed vary.
It has to be said that the popularity of alphanumeric LEDs has decreased recently and although various people have theories about why this is (including the TV show 24 being canceled), it is more than likely a result of LCD advancements, that offer increased flexibility visually and use considerably less energy. They are still important enough to talk about though.
Within this sub-type of Application-specific LEDs there are actually 4 alphanumeric sub-types:
- 7-segment – Alphanumeric LED that handles a specific set of letters and all the numbers
- 4- and 16-segment – These are alphanumeric LEDs commonly known as star-burst displays, because they can cover the entire Roman Alphabet in upper case along with the numbers 0 to 9. The reason these two have been put together is that the only thing that differs between them is that the 16-segment LED has a break on the bottom and top bars, to enhance how some characters look.
- Matrix – This is the most versatile kind of alphanumeric LED and handles both lower case and upper case versions of the alphabet, every number and even a wide range of symbols too.
RGB or Red Green Blue LEDs
RGB LEDs consist of red, green and blue emitters that enable the 3 colors to be combined in varying amounts to accurately produce different colors. With controllers now being incredibly sophisticated, there is almost no limit to the color combinations that can be utilized by RGB LEDs.
The majority use a common lead, like cathode or anode with a 4-pin connection. This is by far the longest connection used by any LED, as others tend to have a built-in electronic control unit and 2 leads.
RGB LEDs offer incredible control of the emitted colors to users, because electronic circuits are used to control the diffusion and mixing of colors. Therefore, RGB LEDs are used in various ways, as status indicators, accent lighting, for video display and light shows, to name but a few.
Bi-color and Tri-color LEDs
Inside a bi-color LED you will find 2 light-emitting dies and consists of 3 leads and a common cathode or anode. Bi-color LEDs use what is known as inverse parallel wiring, meaning one is backward and one is forward, which in turn, means only one die can be on at one time. Color variation is produced when the flowing current alternates between the two dies. A third color can produced if you alternate the flowing current at very high frequency so it appears the two lights were on at the same time..
Similarly, tri-color LEDs consist of two light-emitting dies in one casing. The difference is, in a tri-color, there are 3 leads – 2 outer leads (common anodes for the LEDs) at either side of a central lead (common cathode or the LEDs). With this design, both dies can either be lit at the same time or separately, producing a third color.
Although the above describes the most common design using a cathode, there are tri-color LEDs available with both common cathode and anode configurations.
Flashing LEDs are normally used as a kind of attention-grabbing indicator. Although for the most part they may look like a standard LED from the outside, there is an integrated circuit that sits alongside the LED and flashes the appropriate light at particular frequencies. Flashing LEDs are specifically designed to allow direct connection to a power supply without the need for a series resistor. They are often used on signs and in cars and other similar applications.