3.1mm Through-Hole LED Lamp Super Red 639nm - 2.4V 20mA - 400mcd - English Datasheet

1. Product Overview

This document details the specifications for a high-performance, 3.1mm diameter through-hole LED lamp. The device utilizes AlInGaP (Aluminum Indium Gallium Phosphide) technology to produce a Super Red light output. It is designed for general-purpose indicator and illumination applications across various electronic equipment, offering a balance of high luminous intensity, low power consumption, and reliable operation.

The core advantages of this LED include its high efficiency, which allows for bright output at relatively low drive currents, making it compatible with integrated circuits. Its versatile package enables straightforward mounting on printed circuit boards (PCBs) or panels. The primary target markets are consumer electronics, industrial controls, communication devices, and office equipment where clear, reliable visual indicators are required.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

The device's operational limits are defined to ensure long-term reliability. The maximum continuous power dissipation is 75 mW at an ambient temperature (T_A) of 25°C. The DC forward current should not exceed 30 mA. For pulsed operation, a peak forward current of 90 mA is permissible under specific conditions: a 1/10 duty cycle and a 0.1ms pulse width. The maximum reverse voltage rating is 5 V. The operating and storage temperature ranges are from -40°C to +100°C. For soldering, leads can withstand 260°C for 5 seconds when measured 1.6mm from the LED body. A derating factor of 0.4 mA/°C applies for the forward current above 50°C ambient temperature.

2.2 Electrical & Optical Characteristics

Key performance parameters are measured at T_A=25°C and I_F=20mA. The luminous intensity (I_V) has a typical value of 400 millicandelas (mcd), with a minimum of 140 mcd. The light distribution is characterized by a 45-degree viewing angle (2θ_1/2), defined as the off-axis angle where intensity drops to half its axial value.

The spectral characteristics include a peak emission wavelength (λ_P) of 639 nm and a dominant wavelength (λ_d) of 631 nm, which defines the perceived color. The spectral line half-width (Δλ) is 20 nm. Electrically, the forward voltage (V_F) typically measures 2.4 V, with a maximum of 2.4 V at 20mA. The reverse current (I_R) is a maximum of 100 µA at 5 V reverse bias, and the junction capacitance (C) is 40 pF measured at 0V and 1MHz.

3. Binning System Explanation

To ensure consistency in applications, LEDs are sorted into bins based on key parameters.

3.1 Luminous Intensity Binning

Luminous intensity is classified into bins denoted by two-letter codes. For example, bin 'GH' covers intensities from 140 mcd to 240 mcd, 'JK' from 240 mcd to 400 mcd, and 'LM' from 400 mcd to 680 mcd, all measured at 20mA. A tolerance of ±15% applies to each bin limit. The specific bin code is marked on each packing bag for traceability.

3.2 Dominant Wavelength Binning

The dominant wavelength, which defines the color point, is also binned. Codes like H29 to H33 represent specific wavelength ranges in nanometers (e.g., H31: 629.0 – 633.0 nm). The tolerance for each bin limit is ±1 nm. This precise binning allows designers to select LEDs with very tight color consistency for their projects.

4. Performance Curve Analysis

The datasheet references typical performance curves which are crucial for design analysis. These curves, plotted against ambient temperature unless noted otherwise, visually represent the relationship between key parameters. While the specific graphs are not reproduced in text, they typically include:

• Relative Luminous Intensity vs. Forward Current: Shows how light output increases with current, often in a non-linear fashion, highlighting the efficiency point.
• Forward Voltage vs. Forward Current: Illustrates the diode's I-V characteristic, essential for calculating series resistor values and power dissipation.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the thermal derating of light output, which is critical for high-temperature environment applications.
• Spectral Distribution: A graph of relative intensity versus wavelength, showing the concentration of light output around the 639 nm peak and the 20 nm half-width.

These curves enable engineers to predict device behavior under non-standard conditions (different currents, temperatures) and are fundamental for robust circuit design.

5. Mechanical & Package Information

The LED is housed in a 3.1mm diameter round package with a water-clear lens. Key dimensional notes include: all dimensions are in millimeters (with inch equivalents), with a standard tolerance of ±0.25mm unless specified otherwise. The resin under the flange may protrude up to 1.0mm maximum. Lead spacing is measured at the point where the leads emerge from the package body. A detailed dimensioned drawing would typically show the body diameter, lens shape, lead length, and lead diameter, which are critical for PCB footprint design and panel cut-out sizing.

6. Soldering & Assembly Guidelines

6.1 Lead Forming

If leads need to be bent, this must be done before soldering and at normal room temperature. The bend should be made at a point at least 3mm away from the base of the LED lens. Crucially, the base of the lead frame itself must not be used as a fulcrum during bending, as this can stress the internal die attach.

6.2 Soldering Parameters

A minimum clearance of 2mm must be maintained between the base of the lens and the soldering point. The lens must never be immersed in solder. Recommended conditions are:

• Hand Soldering (Iron): Maximum temperature 300°C, maximum time 3 seconds per lead (one time only).
• Wave Soldering: Maximum pre-heat temperature 100°C for up to 60 seconds. Solder wave temperature maximum 260°C with a maximum contact time of 10 seconds.

Exceeding these temperature or time limits can cause lens deformation or catastrophic failure of the LED.

6.3 Storage & Handling

For long-term storage outside the original packaging, it is recommended to place LEDs in a sealed container with desiccant or in a nitrogen ambient. Components out of their original pack should ideally be used within three months. The storage environment should not exceed 30°C and 70% relative humidity. For cleaning, only alcohol-based solvents like isopropyl alcohol should be used.

7. Packaging & Ordering Information

The standard packaging specification is tiered: 1000, 500, or 250 pieces per anti-static packing bag. Ten of these bags are placed into an inner carton, totaling 10,000 pieces. Eight inner cartons are then packed into a master outer carton, resulting in a standard shipping quantity of 80,000 pieces per lot. It is noted that within a shipping lot, only the final pack may contain a non-full quantity. The specific part number listed is LTL1CHKRKNN.

8. Application Recommendations

8.1 Typical Application Circuits

LEDs are current-driven devices. To ensure uniform brightness when multiple LEDs are connected in parallel, it is strongly recommended to use a individual current-limiting resistor in series with each LED. The alternative, connecting multiple LEDs in parallel directly to a single resistor (Circuit B in the datasheet), is discouraged because small variances in the forward voltage (V_F) characteristic of each LED can cause significant differences in current sharing and, consequently, perceived brightness.

8.2 ESD (Electrostatic Discharge) Protection

This LED is susceptible to damage from electrostatic discharge. A comprehensive ESD control program should be implemented during handling and assembly. This includes: using grounded wrist straps or anti-static gloves; ensuring all equipment, workstations, and storage racks are properly grounded; and employing ionizers to neutralize static charge that may accumulate on the plastic lens surface due to handling friction.

8.3 Application Scope & Cautions

This LED is intended for ordinary electronic equipment. For applications requiring exceptional reliability where failure could jeopardize life or health (e.g., aviation, medical devices, critical safety systems), specific consultation and qualification are necessary prior to use.

9. Technical Comparison & Differentiation

Compared to older technologies like standard GaAsP (Gallium Arsenide Phosphide) red LEDs, this AlInGaP-based Super Red LED offers significantly higher luminous efficiency. This means it can achieve much greater light output (measured in mcd) for the same 20mA drive current, or it can deliver similar brightness at a lower current, reducing overall system power consumption. The 3.1mm diameter is a common industry standard, ensuring broad compatibility with existing PCB layouts and panel cutouts designed for "T-1" sized LEDs. The water-clear lens, as opposed to a diffused lens, provides the highest possible axial luminous intensity, making it suitable for applications requiring a bright, focused point of light.

10. Frequently Asked Questions (FAQs)

Q: Can I drive this LED directly from a 5V logic output?
A: No. With a typical V_F of 2.4V, connecting it directly to 5V would cause excessive current to flow, destroying the LED. A series resistor must always be used to limit the current to the desired value (e.g., 20mA). The resistor value is calculated as R = (V_supply - V_F) / I_F.

Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λ_P) is the single wavelength where the spectral output is physically the strongest (639 nm here). Dominant wavelength (λ_d) is a calculated value (631 nm here) derived from the color coordinates on the CIE chromaticity diagram; it represents the single wavelength of pure spectral light that would be perceived by the human eye as having the same color as the LED's mixed output.

Q: How do I interpret the viewing angle?
A: A 45-degree viewing angle (2θ_1/2 = 45°) means the half-intensity point is at 22.5 degrees off the central axis. Light is visible beyond this angle but at lower intensity. This defines the beam width of the LED.

11. Practical Design & Usage Examples

Example 1: Status Indicator on a Power Supply. A single LED with a series resistor can indicate "power on." Using the typical V_F of 2.4V and a desired I_F of 20mA from a 12V rail, the resistor value would be (12V - 2.4V) / 0.02A = 480 Ohms. A standard 470 Ohm or 510 Ohm resistor would be suitable. The power dissipated in the resistor is (12V-2.4V)*0.02A = 0.192W, so a 1/4-watt resistor is sufficient.

Example 2: Multi-LED Bar Graph Display. For a 10-segment bar graph, the recommended design is to use 10 separate current-limiting resistors, each connected in series with its own LED. All LED-resistor pairs are then connected in parallel to the driving voltage source. This ensures each LED receives the correct current regardless of minor V_F variations, guaranteeing uniform segment brightness.

12. Operating Principle Introduction

This LED is a semiconductor diode based on AlInGaP materials. When a forward voltage exceeding the diode's junction potential (approximately 2.0-2.4V) is applied, electrons and holes are injected into the active region from the n-type and p-type materials, respectively. These charge carriers recombine, releasing energy in the form of photons (light). The specific composition of the AlInGaP crystal lattice determines the bandgap energy, which directly corresponds to the wavelength (color) of the emitted light—in this case, in the red spectrum around 639 nm. The water-clear epoxy lens encapsulates the semiconductor chip, provides mechanical protection, and shapes the light output pattern.

13. Technology Trends

The development of AlInGaP materials represented a significant advancement over earlier red LED technologies, offering vastly improved efficiency and brightness. The general trend in indicator LEDs continues towards higher efficiency (more light output per watt of electrical input), which allows for lower power consumption and reduced heat generation in end products. There is also a drive towards tighter binning tolerances for both color and intensity to meet the demands of applications requiring high visual consistency, such as full-color displays and automotive clusters. While surface-mount device (SMD) packages dominate new designs for miniaturization, through-hole LEDs like this one remain relevant for prototyping, repair, legacy systems, and applications where mechanical robustness and ease of hand-soldering are prioritized.