LEDs, which stands for Light Emitting Diodes, are semiconductor devices that efficiently convert electrical energy into light. This is in contrast to traditional incandescent bulbs, which generate light through the conversion of electrical energy into heat, making them much less efficient.

Structurally, an LED is a specialized semiconductor component with a p-n junction. It consists of three layers: a P-type region at the top, an N-type region at the bottom, and an active or depletion region in the middle. When a forward-biased voltage is applied, electrons from the N-region and holes from the P-region move into the active region and recombine. This recombination of charge carriers releases energy in the form of photons, which produces visible light.

The color of an LED can be red, yellow, green, or white, and is determined by the specific semiconductor materials used. Each material has a unique energy bandgap, which is the energy difference between the valence band (where electrons are normally located) and the conduction band (where electrons are free to move and conduct electricity).

The table below shows some common semiconductor materials used in LEDs and the corresponding colors of light they emit:

Diode and LED Polarity

LEDs are polarized components, meaning they must be connected to a circuit in a specific orientation. Like regular diodes, LEDs are represented by a symbol that includes two terminals: the anode (positive) and the cathode (negative). The symbol for a diode features a black arrow (▶), which indicates the direction of forward current flow, from the anode to the cathode. LEDs use the same symbol, but with two small arrows added to indicate their light-emitting function.

To identify the cathode side of a diode, look for a line on the diode’s surface that matches the line in the symbol. For LEDs, identifying the cathode is even easier: simply find the longer leg, which typically corresponds to the positive anode pin. If the legs are damaged or indistinguishable, check for a flat edge on the LED’s casing; the pin closest to this flat edge is the negative cathode pin.

Special Types of LEDs

In addition to the standard DIP and SMD LEDs, there are several unique types of LEDs that can create mesmerizing lighting effects. Two notable examples are addressable LEDs and wireless LEDs.

Addressable LED

Addressable LEDs can be controlled individually or in groups, which is what makes them unique. They allow for the creation of dynamic lighting effects across different parts of the LED strip at the same time or in customizable intervals, offering a wide range of creative possibilities. Each LED comes with a built-in controller that communicates using a digital protocol, passing data from one LED to the next in a serial daisy-chain. This enables a microcontroller or LED controller to send precise commands for individual colors and brightness. This level of control offers greater versatility compared to standard RGB strips with a single control chip, unlocking more creative potential.

Wireless LED

Imagine LEDs that work without any wires or soldering. That’s exactly what wireless LEDs, or inductive LEDs, offer. Inductive coupling is the most common method of wireless power transmission for LED lights. It works by using two coils of wire to generate a magnetic field. When the two coils are close together, the magnetic field induces a current in the receiver coil, which powers the LED lights. The potential applications for wireless LEDs are virtually limitless. For example, you could use them for a fun and eye-catching cosplay outfit, or incorporate them into stunning and versatile lighting designs for your home.

If you have any questions about PCBs and PCBA, please feel free to contact me at info@wellcircuits.com