Editing Light-emitting diode (section)

=== Application-specific ===
{{more citations needed|section|date=October 2020}}
[[File:RGB-SMD-LED.jpg|thumb|RGB-SMD-LED]]
[[File:Macro photo of LED matrix.jpg|thumb|upright|Composite image of an {{nowrap|11 × 44}} LED matrix lapel [[name tag]] display using 1608/0603-type SMD LEDs. Top: A little over half of the {{nowrap|21 × 86 mm}} display. Center: Close-up of LEDs in ambient light. Bottom: LEDs in their own red light.]]
; Flashing: Flashing LEDs are used as attention seeking indicators without requiring external electronics. Flashing LEDs resemble standard LEDs but they contain an integrated [[voltage regulator]] and a [[multivibrator]] circuit that causes the LED to flash with a typical period of one second. In diffused lens LEDs, this circuit is visible as a small black dot. Most flashing LEDs emit light of one color, but more sophisticated devices can flash between multiple colors and even fade through a color sequence using RGB color mixing. Flashing SMD LEDs in the 0805 and other size formats have been available since early 2019.
; Flickering: [[File:IR-Led-Die.jpg|thumb|Infrared light from the LED die of IR LED as seen by a digital camera]]Simple electronic circuits integrated into the LED package have been around since at least 2011 which produce a random LED intensity pattern reminiscent of a flickering [[candle]].<ref>{{Cite web |last=Oskay |first=Windell |date=2011-06-22 |title=Does this LED sound funny to you? |url=https://www.evilmadscientist.com/2011/does-this-led-sound-funny-to-you/ |url-status=live |archive-url=https://web.archive.org/web/20230924100327/https://www.evilmadscientist.com/2011/does-this-led-sound-funny-to-you/ |archive-date=2023-09-24 |access-date=2024-01-30 |website=Evil Mad Scientist Laboratories |language=en-US}}</ref> [[Reverse engineering]] in 2024 has suggested that some flickering LEDs with automatic sleep and wake modes might be using an integrated [[8-bit computing|8-bit]] [[microcontroller]] for such functionally.<ref>{{Cite web |last=Tim's Blog |date=2024-01-14 |title=Revisiting Candle Flicker-LEDs: Now with integrated Timer |url=https://cpldcpu.wordpress.com/2024/01/14/revisiting-candle-flicker-leds-now-with-integrated-timer/ |url-status=live |archive-url=https://web.archive.org/web/20240129164612/https://cpldcpu.wordpress.com/2024/01/14/revisiting-candle-flicker-leds-now-with-integrated-timer/ |archive-date=2024-01-29 |access-date=2024-01-30 |website=cpldcpu.wordpress.com |language=en}}</ref> Sometimes a flickering effect might happen due to an electric malfunction.<ref>{{Cite web |date=2025-03-06 |title=What Can Cause Room Light to Flicker? |url=https://comiled.com/blogs/news/what-can-cause-room-light-to-flicker |access-date=2025-04-16 |website=ComiLED |language=en}}</ref>
; Bi-color: Bi-color LEDs contain two different LED emitters in one case. There are two types of these. One type consists of two dies connected to the same two leads [[Antiparallel (electronics)|antiparallel]] to each other. Current flow in one direction emits one color, and current in the opposite direction emits the other color. The other type consists of two dies with separate leads for both dies and another lead for common anode or cathode so that they can be controlled independently. The most common bi-color combination is [[RG color space|red/traditional green]]. Others include amber/traditional green, red/pure green, red/blue, and blue/pure green.
; RGB tri-color: Tri-color LEDs contain three different LED emitters in one case. Each emitter is connected to a separate lead so they can be controlled independently. A four-lead arrangement is typical with one common lead (anode or cathode) and an additional lead for each color. Others have only two leads (positive and negative) and have a built-in electronic controller. [[RGB color model|RGB]] LEDs consist of one red, one green, and one blue LED.<ref>{{Cite book |url=https://books.google.com/books?id=qk1hmpEQVxIC&pg=PA349 |title=5th Kuala Lumpur International Conference on Biomedical Engineering 2011: BIOMED 2011, 20–23 June 2011, Kuala Lumpur, Malaysia |last=Ting |first=Hua-Nong |date=2011-06-17|publisher=Springer Science & Business Media |isbn=9783642217296}}</ref> By independently [[pulse-width modulation|adjusting]] each of the three, RGB LEDs are capable of producing a wide color gamut. Unlike dedicated-color LEDs, these do not produce pure wavelengths. Modules may not be optimized for smooth color mixing.
; Decorative-multicolor: Decorative-multicolor LEDs incorporate several emitters of different colors supplied by only two lead-out wires. Colors are switched internally by varying the supply voltage.
; Alphanumeric: Alphanumeric LEDs are available in [[seven-segment display|seven-segment]], [[Starburst display|starburst]], and [[Dot-matrix display|dot-matrix]] format. Seven-segment displays handle all numbers and a limited set of letters. Starburst displays can display all letters. Dot-matrix displays typically use 5×7 pixels per character. Seven-segment LED displays were in widespread use in the 1970s and 1980s, but rising use of [[liquid crystal display]]s, with their lower power needs and greater display flexibility, has reduced the popularity of numeric and alphanumeric LED displays.
; Digital RGB: Digital RGB addressable LEDs contain their own "smart" control electronics. In addition to power and ground, these provide connections for data-in, data-out, clock and sometimes a strobe signal. These are connected in a [[Daisy chain (electrical engineering)|daisy chain]], which allows individual LEDs in a long [[LED strip light]] to be easily controlled by a microcontroller. Data sent to the first LED of the chain can control the brightness and color of each LED independently of the others. They are used where a combination of maximum control and minimum visible electronics are needed such as strings for Christmas and LED matrices. Some even have refresh rates in the kHz range, allowing for basic video applications. These devices are known by their part number ([https://cdn-shop.adafruit.com/datasheets/WS2812.pdf WS2812] being common) or a brand name such as [[Adafruit Industries#NeoPixel|NeoPixel]].
; Filament: An [[LED filament]] consists of multiple LED chips connected in series on a common longitudinal substrate that forms a thin rod reminiscent of a traditional incandescent filament.<ref>{{cite web|url=http://www.ledinside.com/knowledge/2015/2/the_next_generation_of_led_filament_bulbs|title=The Next Generation of LED Filament Bulbs|website=LEDInside.com|publisher=Trendforce|access-date=October 26, 2015}}</ref> These are being used as a low-cost decorative alternative for traditional light bulbs that are being phased out in many countries. The filaments use a rather high voltage, allowing them to work efficiently with mains voltages. Often a simple rectifier and capacitive current limiting are employed to create a low-cost replacement for a traditional light bulb without the complexity of the low voltage, high current converter that single die LEDs need.<ref>Archived at [https://ghostarchive.org/varchive/youtube/20211211/H_XiunR-cAQ Ghostarchive]{{cbignore}} and the {{usurped|1=[https://web.archive.org/web/20151122213511/https://www.youtube.com/watch?v=H_XiunR-cAQ Wayback Machine]}}{{cbignore}}: {{cite web|url=https://www.youtube.com/watch?v=H_XiunR-cAQ|title=LED Filaments|website=[[YouTube]]|date=April 5, 2015 |access-date=October 26, 2015}}{{cbignore}}</ref> Usually, they are packaged in bulb similar to the lamps they were designed to replace, and filled with inert gas at slightly lower than ambient pressure to remove heat efficiently and prevent corrosion.
; Chip-on-board arrays: Surface-mounted LEDs are frequently produced in [[chip on board]] (COB) arrays, allowing better heat dissipation than with a single LED of comparable luminous output.<ref>{{cite book|title=Handbook on the Physics and Chemistry of Rare Earths: Including Actinides|url=https://books.google.com/books?id=lO_lCgAAQBAJ&pg=PA89|date=1 August 2016|publisher=Elsevier Science|isbn=978-0-444-63705-5|page=89}}</ref> The LEDs can be arranged around a cylinder, and are called "corn cob lights" because of the rows of yellow LEDs.<ref>{{cite web |title=Corn Lamps: What Are They & Where Can I Use Them? |date=September 1, 2016 |publisher=Shine Retrofits |url=https://www.shineretrofits.com/lighting-center/corn-lamps |access-date=December 30, 2018}}</ref>