From Robotics

Definition: Light Emitting Diodes (LEDs) are compound semiconductor devices that convert electricity to light when biased in the forward direction. Because of its small size, ruggedness, fast switching, low power, and compatibility with integrated circuitry, LED was developed for many indicator-type applications.

Today, advanced high-brightness LEDs are the next generation of lighting technology and are currently being installed in a variety of lighting applications. As a result of breakthroughs in material efficiencies and optoelectronic packaging design, LEDs are no longer used in just indicator lamps. They are used as a light source for illumination for monochromatic applications such as traffic signals, brake lights, and commercial signage.

LED Benefits

  • Energy efficient
  • Compact size
  • Low wattage
  • Low heat
  • Long life
  • Extremely robust
  • Compatible with integrated circuits

FIGURE 3.20 Parts of an LED

FIGURE 3.20 Parts of an LED.

LED Structure
  • Chip
  • Lead frame
  • Gold wire
  • Epoxy resin (plastic mold package)
  • Cathode
  • Anode
  TABLE 3.3   Semiconductors for LEDs
Green, Red
Red, Infrared
Red, Infrared

Yellow, Red
Green Green

Yellow, Orange,

Classification: Classification of LEDs are defined by spectrum.
(i) Visible LED: Based on max. spectrum, produces red, orange, yellow, green, blue, and white.
(ii) Infrared LED: (IR LED).

Applications of LEDs
Visible LED: General-purpose application in various industries including indication devices for electronic appliances, measuring instruments, etc.
Bi-color (dual color) LED: Charger for cellular phones, showcase boards, traffic boards on highways, etc.
High & Ultra Brightness LED: Full-color display for indoor/outdoor, automotive signal lamps, high-mount lamps, indoor lamps, traffic signal lamps, etc.
Infrared LED: With high output capacity, IR LED is used in remote controls, IrDa ( Infrared Data Storage Devices), etc.

Products & Services
DC Motors
DC motors are most commonly used in variable speed and torque applications. They include brushless and gear motors, as well as servomotors.
Stepper Motors (rotary)
Stepper motors use a magnetic field to move a rotor in small angular steps or fractions of steps. They provide precise positioning and ease of use, especially in low acceleration or static load applications.
DC Servomotors
DC servomotors are generally small and powerful for their size, and easy to control. Common types of DC servomotors include brushless or gear motors.
Tactile Pressure Sensors
Tactile pressure sensors are used to detect the pressure distribution between a sensor and a target.
Capacitors are electronic components used for storing charge and energy. In their simplest form, capacitors consist of two conducting plates separated by an insulating material called the dielectric.

Topics of Interest

A semiconductor device consisting of two P-N junctions formed by either a P-type or N-type semiconductor between a pair of opposite types is known as a transistor. FIGURE 3.21 A transistor in which...

9.3.1 Light-Emitting Diodes (LEDs) A light-emitting diode is a semiconductor diode that is forwardbiased so carriers recombining at a junction spontaneously emit light. That light is spontaneous...

Overview A large number of embedded systems offer some form of display device to convey information to the user. The display can consist of anything from a light indicating that power is on, to a...

GLT Introduces Tri-Color Molded LED Backlights Strongsville, Ohio, February 5 - New Tri-Color LED Molded Backlights from Global Lighting Technologies, Inc. (GLTI), Inc. employ patented...

An RGB LED can be driven with a combined 60mA constant current source supply from an AAT3123. This is accomplished by connecting the four constant current source outputs (D1 to D4) from an AAT3123 and...