LED Indicator Glossary

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Addressable LEDs
Addressable LEDs (also known as individually addressable LEDs or smart LEDs) are colorful light-emitting diodes that can be controlled and programmed individually or in groups via a microcontroller. Each addressable LED has a microchip that can process digital signals and respond to specific commands, allowing for complex lighting effects and animations. Addressable LEDs are commonly used in applications where precise and dynamic control of lighting is desired.

Aluminum Gallium Arsenide, which is a semiconductor material used in various electronic devices like LED indicators. AlGaAs LEDs can generally produce red and infrared colors.

Aluminum Indium Gallium Phosphide. It is a semiconductor material that is commonly used in the production of high-brightness light-emitting diodes (LEDs). AlInGaP LEDs can produce a wide range of colors, including red, orange, amber, and yellow.

Aluminum Indium Gallium Nitride is a semiconductor material used in the manufacturing of light emitting diodes (LEDs). AlInGaN LEDs can produce a range of colors including blue, green, and violet. By combining these colors, other colors such as white can also be produced.

A unit of length equal to 1/10th billion of a meter.

Multiple LEDs, either single or multi-level, arranged horizontally.

Illumination by an indicator of a front panel legend from behind, without protrusion of the LED through the panel.

Bi-Color LED
A component that contains two LED dice of different colors in a single substrate or lead frame carrier. The components have either two, three, or four lead wires for turning the devices on and off.

View Dialight Bi-Color LED indicators

Bi-Level Circuit Board Indicator
Two LEDs stacked vertically in a single housing.

View Dialight Bi-Level LED indicators

Candela (cd)
The standard unit measure of luminous intensity which is used to calculate lumen and foot candle measurements.

The trademarked name of Dialight's Circuit Board Indicator Series of LED indicator solutions.

View Dialight CBI® LED circuit board indicators

Ratings and Certifications for a particular product SKU. All documentation can be requested via the ASSENT PORTAL.
See also RoHS, RoHS w/ 6C exemption, IK07, IK10, IP66, IP67, NEMA4X, UL 94, Watertight to Mil-L-3661B Spec, Class 1 Div 2

Chromaticity Coordinates (xy)
A way to describe the color of light emitted by a source, such as white LEDs. They are commonly represented by two values, typically denoted as (x, y), which correspond to the location of the light source on the CIE xy chromaticity diagram.
For white LEDs, the chromaticity coordinates indicate the color temperature or tint of the emitted light. The color temperature is a measure of the perceived warmth or coolness of the light, with lower values representing warmer (more yellowish) light and higher values representing cooler (more bluish) light.
For example, a cool white LED might have chromaticity coordinates of around (0.30, 0.31) on the CIE xy diagram, while a warm white LED might have coordinates of around (0.40, 0.40).

Class 1 Div 2 (C1D2)
is a certification given to electrical and electronic equipment that is suitable for use in hazardous locations, where a potentially explosive atmosphere may be present under normal operating conditions. LED indicators with a Class 1 Division 2 certification are designed to be used in locations where the possibility of an explosion is low, but still possible. They are designed to withstand harsh environmental conditions, such as extreme temperatures, moisture, and vibration.

View Dialight Class 1 Div 2 (C1D2) LED indicators

Color Rendering Index (CRI)
CRI is a measure of how accurately an LED light source can reproduce the colors of objects compared to a natural light source, such as sunlight.
It is typically rated on a scale from 0 to 100, with a higher CRI indicating better color accuracy.
A CRI of 100 indicates that the light source accurately renders colors.

Continuous Forward Current
The current that must be applied to the p-side of an optoelectronic device - such as an LED to produce a given output.

Constant Intensity LED Indicator
A type of LED indicator that maintains a consistent level of brightness or luminosity regardless of any fluctuations in voltage or current.

Correlated Color Temperature (CCT)
A metric used to describe the color appearance of a light source, such as LEDs. It measures the color of light emitted by the source in relation to a black body radiator at a particular temperature. The CCT is expressed in Kelvin (K) and is commonly used to describe the "warmth" or "coolness" of white light.

Countersink Light Pipes
A vertical, panel mount light pipe series that installs flush into the panel and provides a seamless appearance when an indicator cannot protrude from the panel due to safety reasons or aesthetics. Ideally suited for backlighting applications with laminate overlays.

Learn more about Dialight Optopipe® Countersink Light Pipes...

View Dialight Optopipe® Countersink Light Pipes

The undesired illumination of one indicator position by the light source from another. This can cause false or confusing indication signals. Crosstalk can be prevented with Light Shields.

Current Limiting Resistor
A protective resistor added in-line between the power source and the light source to regulate the current delivered to the device. The value of the resistor depends on the operating voltage of the circuit.

Daylight Viewable LED Indicator
A type of LED indicator that is designed to be easily visible in daylight conditions. It usually has a higher brightness level compared to typical LED indicators and is designed to be visible even in direct sunlight. This type of LED indicator is commonly used in outdoor applications and industrial settings where visibility is important.

View Dialight Daylight Viewable LED Indicators

Diagnostic Application
One of two applications served by circuit board indicators (the other being front panel applications). In diagnostic applications, the indicator is mounted on a circuit board, generally without secondary optics, and is viewed at close range by a service technician inside a piece of equipment.

The basic semiconductor device or "chip" inside the LED assembly.

Glass particles suspended in the epoxy lens of an LED that diffuse the light and broadens the device's viewing angle.

Direct View
The application of an indicator in which its lens protrudes through the front panel and is viewed directly.

Discrete LED
A single LED that is not part of a larger electronic circuit or indicator with multiple LEDs.

Dominant Wavelength
Dominant wavelength is a metric used to describe the perceived color of an LED light.
It refers to the specific wavelength of light that appears most prominent in the spectrum emitted by the LED.
For example, in a red LED, the dominant wavelength would be in the red part of the spectrum.

Efficacy in LED lighting refers to the efficiency of converting electrical energy into visible light. It is typically measured in lumens per watt (lm/W).
Higher efficacy values indicate that an LED produces more lumens of light for each watt of electrical power consumed, making it more energy-efficient.

The non-thermal conversion of electrical energy into light. In an LED, it is produced by electron-hole recombination in the p-n junction.

Electrostatic Discharge (ESD)
Is the sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown. It can occur when the objects have different electric charges, and the accumulated charge on one of the objects suddenly discharges to the other object. This can result in damage to LEDs and other electronic components.

A resin characterized by high adhesiveness, toughness, and corrosion resistance. Used to surround LED die to provide attributes - such as diffusion and lens shape.

See Electrostatic Discharge

F (Part Number Ending)
Part numbers for Dialight LED Indicators ending with the letter F are designated as RoHS Compliant.
Example: 596-2429-013F
Note: Part numbers without F ending may be RoHS compliant. Please Contact Us to inquire.

See also RoHS

Flexible Light Pipe
A type of light pipe that is made of a flexible optical material/fiber. It can be bent to fit around other components on a circuit board to transmit light from LEDs to a panel or HMI surface.

Foot Candle
A unit for measuring illumination. One foot candle equals the amount of light delivered by a 1 candela light source to a 1 square foot surface 1 foot away.

Front Panel Application
The application of an LED in which the light is viewed at the front panel of the host equipment. This usually requires either backlighting or direct-view configuration.

Forward Voltage
The voltage that must be applied to the p-side of an optoelectronic device - such as an LED to produce a given output.

Gallium Arsenide is a compound semiconductor made of gallium and arsenic. It is commonly used in the electronics industry for manufacturing high-frequency and high-power devices such as LED lights. Generally, GaAs LEDs produce red or infrared light. However, by varying the composition of the material, it is possible to achieve different wavelengths of light and therefore different colors.

Gallium Phosphide is a semiconductor material used in electronic devices like light emitting diodes (LEDs). Gallium Phosphide (GaP) LEDs typically emit in the green to yellow-green wavelengths ranging from 550-650 nanometers (nm) and can produce colors such as yellow-green, green, and yellow.

Human Machine Interface (HMI)
Is a user interface or dashboard that connects a human operator to a machine, system, or device.

IK Rating
Impact Protection rating or the Mechanical Impact Protection rating, indicates the level of protection against mechanical impacts that an electronic device or appliance can withstand. It is a standard that classifies the degree of impact resistance of the device on a scale of 0 to 10, with 0 being the least and 10 being the highest level of protection. Ie. IK07 vs IK10

Emission of light through thermal excitation resulting from the superheating of a conductor. The excitation must be sufficient to produce enough photons to make the light source visible.

Incandescent Lamp
A light source based on incandescence in which voltage is passed through a filament that heats to create light.

Indium Gallium Nitride is a semiconductor material used in the production of light-emitting diodes (LEDs). InGaN LEDs can produce a wide range of colors including blue, green, white, and ultraviolet.

Integral Resistor
An LED design option in which the current limiting resistor is contained within the package.

See Luminous Intensity

The region of the electromagnetic spectrum between the long wavelength extreme of the visible spectrum (700 nm) and the shortest microwave frequencies (1 nm). Nearly all of the infrared portion of the spectrum is invisible to the human eye. Infrared LEDs are used in sensing, data transmission, ambient light detection, and other various applications.

IP Rating
Ingress Protection rating is a measure of how well a device or enclosure can protect against the intrusion of foreign objects such as dust, water, or other substances. The rating consists of two digits, with the first digit indicating the level of protection against solid objects and the second digit indicating the level of protection against liquids. The higher the number, the better the protection against intrusion. ie. IP66 vs IP67

Lead Frame
A metal structure to which a semiconductor die is attached. The lead frame provides stability for the devices and completes the electrical path to the die.

LED Drivers
LED drivers are electronic components that regulate the power supply to LEDs.
They provide the necessary voltage and current to operate the LED at the desired brightness while protecting it from voltage fluctuations and overcurrent.
LED drivers are crucial for ensuring the longevity and proper performance of LEDs.

LED Phosphor
LED phosphors are substances or coatings applied to the LED chip that help convert the primary blue or ultraviolet light emitted by the LED into a broader spectrum of colors, including white light. Phosphors are commonly used in white LEDs to achieve different color temperatures and improve color quality.

L.E.D. Position
Indicates if the LED(s) on a given circuit board indicator are either protruding or recessed.

The epoxy enclosure molded to an LED die to provide optical characteristics.

Lens Finish
Refers to surface condition of light pipe lenses, which can either be clear or diffused. A clear lens on a light pipe allows for a clear and direct transmission of light, resulting in a brighter and more focused output. On the other hand, a diffused lens scatters the light, creating a softer and more even illumination that offers more side view capabilities.

Lens Shape
Lenses can be either round, square, or rectangular in shape to match or create the desired front panel (HMI) look.

Lens Optics
Refers to the output side of the lens of a light pipe, which can be either flat, convex, or domed. Each type provides a different level of light distribution.

A flat lens is used when you want the light to be distributed evenly and in the same direction as the LED. This is the most common type of LED light pipe.

A convex lens is used when you want the light to be spread over a wider area, such as for indicators or backlighting. These types of lenses also help to increase the brightness of the LED light pipe, making it more visible to the user.

A domed lens is used when you want the light to be distributed in a wide angle and provide a more uniform illumination. This type of lens is commonly used for panel mounting, display indication, and in areas that require a large viewing angle.

Number of vertical positions of LEDs in an indicator or light pipe configuration.

Light Bleed
Is light escaping from the edges of a light pipe. It diminishes the overall light output and may allow light where it should not be visible. Light bleed in light pipes can be prevented by Light Shields.

Light Emitting Diode (LED)
A p-n junction semiconductor device that emits incoherent, monochromatic optical radiation when biased in the forward direction.

Light Pipe
An optical conduit made of molded plastic that directs the light from an LED to the viewing location, often at a right angle from the circuit board.
Learn more about Light Pipes...

View all Dialight Optopipe® Light Pipes.

Light Shield
An optical barrier or housing for a light pipe that reduces light bleed, prevents optical crosstalk, enhances contrast, and improves durability.

View Dialight Optopipe® Light Pipes with Light Shields

A unit of luminous flux, equal to the luminous flux emitted by a standard point source having a luminous intensity of one candela.

Luminous Intensity
The amount of light emitted by the LED in a specific direction, measured in Millicandela (mcd). It represents the brightness or intensity of the light emitted by the LED, with a higher luminous intensity indicating a brighter LED. This value is often used to determine the suitability of an LED for different applications and to ensure that the LED meets the required brightness standards for its intended use.

Millicandela (mcd)
One-thousandth of a Candela.

Moisture Sensitivity Level (MSL)
Is a rating system for electronic components, including LED indicators, that determines their sensitivity to moisture. The MSL rating for LED indicators indicates how much exposure to moisture the component can withstand before its function is compromised. The higher the MSL rating, the more resistant the LED indicator is to moisture.

Mounting Method
Refers to how the LED indicator or light pipe is fastened to either the circuit board or panel. Mounting methods include Adhesive, Nut and Washer, Press-fit, Snap-In, and Ultrasonic Weld.

Mounting Pin
A mounting pin is typically located on the base of light pipes or PRISM surface mount LED indicators. It is designed to provide a secure and stable mounting point for the LED indicator, allowing it to be easily installed and secured in place on the circuit board. To use a snap-in mounting pin, you typically align it with the corresponding holes in the circuit board and push it into place until it snaps securely into position.

Mounting Type
Refers to the supporting structure the LED indicator is mounted to. The three general types are PCB Mount, Panel Mount, and Switch Mount.

With a PCB Mount, the indicator is fastened directly to a circuit board either via mounting pins or soldered.

Panel Mounts are supported by the front panel or HMI surface of the application and are most commonly held in place via a nut and washer, snap-in tabs, or press-fit option.

For Switch Mounts, the indicator, usually a light pipe, is directly pressed or snapped onto an illuminated switch.

Nanometer (nm)
One billionth of 1 meter. Often used (along with angstroms) to quantify the wavelength of light.

The NEMA 4X rating is a standard used to indicate the degree of protection provided by an enclosure against the ingress of water, dust, and other materials. LED indicators with a NEMA 4X rating are designed to be used in harsh and demanding environments, where exposure to water, dust, and corrosive substances is a concern. These indicators are typically sealed against the outside environment, with a durable and corrosion-resistant enclosure that provides good protection against the ingress of moisture, dust, and other contaminants. Additionally, LED indicators with a NEMA 4X rating are typically designed to withstand high levels of shock and vibration, ensuring that they can operate reliably in rugged environments.

Neon Lamp
A light source that generates a blue or amber light by exciting a neon gas plasma with heated electrodes.

Operating Current
The current that a device - such as an LED, is designed to draw from the power source.

Operating Temperature
The voltage or range of voltages at which a device is designed to operate.

Operating Voltage
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The trade name for Dialight's series of LED light pipes.
View all Dialight Optopipe® Light Pipes.

Organic LED (OLED)
A type of LED consisting of thin films of organic molecules that emit light in response to an electric current.

Panel Mount Indicator (PMI)
An LED indicator that is designed to be mounted on a panel or a surface. It is used to provide visual information to users about a certain condition or state of a system or process. Panel mount indicators are commonly used in industrial and commercial applications to indicate when a machine is running or when a process is complete. They are available in a variety of shapes, sizes, and colors, and can be customized to fit specific applications.

View all Dialight LED Panel Mount Indicators.

Panel Mount Light Pipes
Optical components used to transmit light from surface-mounted LEDs to the front panel of devices or machines. They consist of a transparent optical grade material that is fastened to the panel and sits over an LED mounted on the printed circuit board. They provide a visible indication of a device's status or functioning. They are commonly used in electronic devices, medical and industrial equipment.

View all Dialight Optopipe® Panel Mount Light Pipes.

See Printed Circuit Board

p-n Junction
Holes and electrons combine in the negative (n) region of a positive-negative (p-n) junction semiconductor diode. During these shifts in energy, photons are generated, some of which are absorbed by the semiconductor material, and some of which are emitted as light energy.

Power Dissipation
The amount of power dissipated as heat by a device.

Printed Circuit Board
A Printed Circuit Board (PCB) is a flat board made of insulating materials that contains conductive pathways for electronic circuits. The conductive pathways are usually made of copper and are etched onto the board in a specific pattern to connect electronic components such as LED indicators, resistors, capacitors, and microprocessors. PCBs are commonly used in electronic devices and are essential components in modern electronics manufacturing.

A device used to separate a light beam into its spectral components. In LEDs, the prism directs light output from an LED to the viewing location.

Also the trade name for Dialight's patented through-process SMT LED indicator PRISM®. Learn more about PRISM® SMT LED indicators...

Quad-level Circuit Board Indicator
Four LEDs stacked above each other in a single housing.

Reflector Cup
A coined portion of a lead frame that forms a reflector around the periphery of an LED die and directs Its light output. The reflector cup is an integral part of the device and is unique to the lead frame type rather than substrate-type chip carrier.

View Dialight SMD LEDs with Reflector Cups

Reverse Breakdown Voltage
The reverse voltage applied to a diode, which, if exceeded, will cause the device to fail. Specifically, the value when a diode is reversed biased, that avalanche breakdown occurs.

Reverse Mount LED
An LED package that is designed to be mounted on the underside of a printed circuit board (PCB) with the light emitting surface facing downwards. The LED is flipped upside down and mounted so that it is recessed into a hole in the PCB. This is the opposite of a traditional LED package, which is mounted with the light emitting surface facing up and visible.

View Dialight Reverse Mount LEDs

RGB LEDs are LEDs that emit red, green, and blue light. By combining these three primary colors in varying intensities, RGB LEDs can produce a wide range of colors.
They are commonly used in applications such as displays, decorative lighting, and color-changing lighting systems.

Right-Angle Light Pipe
A light pipe that is designed to bend and transmit the light from an LED on a circuit board at a 90-degree angle.

View all Dialight Optopipe® Right-Angle Light Pipes.

Right-Angle Through Hole LED Indicator
An LED indicator emits light at a right-angle from the circuit board. It houses LEDs with a right-angle bend in their leads that allow it to be inserted into a printed circuit board (PCB) and mounted vertically at a right-angle to the board surface.

View all Dialight Right-Angle Through Hole LED Indicators.

Right-Angle SMD LED
A surface mount LED that emits light at a right-angle from the circuit board.

View all Dialight Right-Angle SMD LEDs.

Right-Angle Surface Mount LED Indicator
A housed, surface mount LED indicator either in single, bi-, or tri-level configuration with silicone lens(es) that emits light at a right-angle from the circuit board.

Learn more about PRISM® Surface Mount LED indicators...

Right Angle Viewing
A type of indicator application in which the light output must be viewed at a right angle (i.e., in a direction parallel to the circuit board).

RoHS (Restriction of Hazardous Substances)
is a regulation that restricts the use of certain hazardous materials in electronics and electrical products sold in the European Union. The prohibited substances include lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBBs), and polybrominated diphenyl ethers (PBDEs). The RoHS directive aims to reduce the amount of hazardous waste generated by electronic products and promote the use of safer materials.

Part numbers for Dialight LED Indicators ending with the letter F are designated as RoHS Compliant.
Example: 596-2429-013F
Note: Part numbers without F ending may be RoHS compliant. Please Contact Us to inquire.

RoHS w/ 6C exemption
The 6C exemption refers to an exemption granted under RoHS for cadmium-based quantum dot displays used in lighting applications. This exemption allows the use of cadmium-based quantum dot displays in specific lighting applications where there are currently no viable alternatives that meet the RoHS standards.

Secondary Optics
Devices that are used to enhance or redirect the light output of an LED. Examples include lenses and light pipes.

A numerical code defining a particular product type offered by Dialight.
515 = Optopipe® Light Pipes

591, 592, 593, 594, 595, 596 = PRISM® SMD right-angle LED indicators

597, 598, 599 = SMD LEDs

658 = 1”, watertight panel mount indicators

Super Bright LED
An LED designed to produce exceptionally high light intensity.

Acronym for surface mount device.

Acronym for surface mount technology.

The lifecycle status of a particular SKU.
Status options include:
Discontinued – Replacement Available
EOL-Not for new Designs
Active – Data Coming Soon.

Storage Temperature
The range of temperatures at which an LED indicator or equipment should be stored to prevent damage.

Surface mount LED (SMD LED)
LED designed to conform of the requirements of the surface mount circuit board manufacturing environment. Surface mount devices must withstand the infrared soldering process, and must be physically compatible with automated pick-and-place equipment.
View Dialight SMD LEDs

Tape and Reel
A type of packaging commonly used for electronic components like LED indicators. In this packaging method, the components are placed on a continuous strip of carrier tape which is wound around a reel. The tape is made of a transparent material that allows for easy visual inspection of the components.
The tape is divided into pockets or cavities, with each pocket holding one LED indicator. The pocketed tape is then sealed with a cover tape to protect the components and prevent any contamination or damage during shipping and handling.
Tape and reel packaging offers several advantages such as ease of handling, protection against damage, high packing density, and compatibility with automated pick-and-place machinery, making it a popular choice for many electronic component manufacturers.

Through-Hole LED
The most common type of LED package. It is connected to the circuit board via its leads that also serve as the interface to the power source. The through-hole LED is not surface mountable.

View Dialight Through-Hole LED Indicators

A color added to the epoxy lens of an LED to identify its color when on.

TIR (Total Internal Reflection) Lens
A type of optical lens that works by using the principle of total internal reflection to control the direction and spread of light. It is typically made of a transparent material like glass or plastic and has a complex shape that allows it to bend and manipulate light in a specific way. TIR lenses are commonly used in applications that require precise control over light, such as in LED lighting, optical communications, and medical devices.

Tri-Level LED
Three LEDs stacked above each other, generally realized with light piping.

View Dialight Tri-Level LED Indicators

Tri-Color LED
A component that contains two LED dice of different colors in a single substrate or lead frame carrier, and able to provide a third color by instantaneous operation of both. The components have either two, three, or four leads for turning the devices on and off.

View Dialight Tri-Color LED Indicators

A safety certification that is given to products by the Underwriter Laboratories organization. UL rating indicates that a product has been tested and verified to meet certain safety standards and can be used safely.

This system rates the burning and extinguishing qualities of plastics.

UV-Resistant LED Indicators
Specialized LED Indicators that are designed to be resistant to ultraviolet (UV) radiation, which is typically found in outdoor environments. These indicators are often used in outdoor applications where they are exposed to direct sunlight and other environmental factors that can cause damage over time.

View Dialight UV Resistant LED Indicators

Vertical Light Pipe
A type of light pipe that transmits light in a straight line from the output side of an LED to the front of the panel or enclosure.

View Dialight Optopipe® Vertical Light Pipes

Viewing Angle
The area in front and to the sides of an LED at which light output falls off 50 percent. The viewable area appears as a cone-shaped pattern.

Visible Spectrum
The light spectrum between 400 and 700 nm, which is detectable by the human eye.

Water Clear LED
An LED die combined with a clear lens that has no tinting is sometimes referred to as a water-clear LED.

Watertight to Mil-L-3661B Spec
A specification for materials used in the construction of watertight equipment, such as LED Indicators and electric cables. When something is described as watertight to Mil-L-3661B spec, it means that it has been designed and tested to meet the requirements of this specification and is certified to provide a high level of protection against water ingress. The specification includes requirements for materials, construction, and testing procedures to ensure that the product is able to withstand exposure to water and other environmental factors without compromising its performance.

XY Variable Optopipe® Light Pipes
Rigid, right-angle light pipe series with a light shield and a 3mm lens diameter. This series is available in standard lengths from 0.319” (8.1mm) to 1.772” (45mm) and heights from 0.2” (5.08mm) to 0.5” (12.7mm). The series offers customization options within the given length and height ranges and provides a greater level of design flexibility when comes to placing light sources on the circuit board and bringing indication to the front panel of the application.

Learn more about XY Variable Optopipe® Light Pipes

Zener Diode
A zener diode is a type of diode that is designed to operate in reverse breakdown mode and maintain a constant voltage drop across its terminals, regardless of the current flowing through it. It is commonly used as a voltage regulator to regulate the voltage in a circuit. They are commonly used for controlling and protecting LEDs.

1. Voltage regulation: If you want to regulate the voltage to your LED(s), you can use a zener diode as a voltage stabilizer. The zener diode will regulate the voltage across the LED, ensuring that it remains constant even if the input voltage varies.

2. Overvoltage protection: If you want to protect your LED(s) from overvoltage such as electrostatic discharge (ESD), you can use a zener diode as a voltage limiter. The zener diode will clamp the voltage at a certain level, preventing it from exceeding the maximum rating of the LED(s).

3. Current limiting: If you want to limit the current flowing through your LED(s), you can use a zener diode in series with the LED(s). The zener diode will act as a current regulator, ensuring that the LED(s) receive only the desired amount of current.

View Dialight SMD LEDs with Zener Diodes