T-1 3mm Red LED LTL42EKEKNN Datasheet - 5mm Body - 2.4V - 75mW - English Technical Document

1. Product Overview

This document details the specifications for a high-efficiency, low-power consumption red LED lamp in a popular T-1 (3mm) diameter through-hole package. The device utilizes an AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material as the light source, encapsulated in a water-clear lens. It is designed for versatile mounting on printed circuit boards (PCBs) or panels and is compatible with integrated circuit (IC) drive levels due to its low current requirements. The primary applications include status indicators, backlighting, and general-purpose illumination in consumer electronics, office equipment, and communication devices where reliable, bright red indication is needed.

2. Technical Parameters Deep Analysis

2.1 Absolute Maximum Ratings

The device is rated for operation within strict environmental and electrical limits to ensure reliability and prevent catastrophic failure. The maximum power dissipation is 75 mW at an ambient temperature (T_A) of 25°C. The DC forward current must not exceed 30 mA continuously. For pulsed operation, a peak forward current of 90 mA is permissible under specific conditions: a 1/10 duty cycle and a pulse width of 0.1 ms. The device can withstand a reverse voltage of up to 5 V. The operating and storage temperature range is specified from -40°C to +100°C. For soldering, the leads can be subjected to 260°C for a maximum of 5 seconds, provided the soldering point is at least 1.6mm (0.063\") from the LED body. A critical derating factor of 0.4 mA/°C applies to the DC forward current for ambient temperatures above 50°C, meaning the allowable continuous current decreases linearly as temperature rises.

2.2 Electrical and Optical Characteristics

Key performance parameters are measured at T_A=25°C and an operating current (I_F) of 20 mA. The luminous intensity (I_V) has a typical value of 880 millicandelas (mcd), with a minimum of 310 mcd, indicating potential binning. The viewing angle (2θ_1/2), defined as the full angle at which intensity drops to half its axial value, is 22 degrees, characteristic of a standard T-1 LED with a narrow beam. The peak emission wavelength (λ_P) is 632 nm, while the dominant wavelength (λ_d), which defines the perceived color, is 624 nm. The spectral line half-width (Δλ) is 20 nm. The forward voltage (V_F) typically measures 2.4V, with a maximum of 2.4V at 20mA. The reverse current (I_R) is a maximum of 100 μA at 5V reverse bias, and the junction capacitance (C) is 40 pF measured at zero bias and 1 MHz.

3. Binning System Explanation

The product is classified according to two key parameters: luminous intensity and dominant wavelength. This binning ensures consistency within a production lot and allows designers to select parts matching specific brightness or color requirements.

3.1 Luminous Intensity Binning

Luminous intensity is categorized into bins with 15% tolerance on each limit. The bins referenced for this product are KL (310-520 mcd) and MN (520-880 mcd). Higher bins like PQ (880-1500 mcd) and RS (1500-2500 mcd) are listed for reference, indicating the technology platform's capability, though they may not be available for this specific part number. The bin code is marked on each packing bag for traceability.

3.2 Dominant Wavelength Binning

The dominant wavelength, which determines the precise shade of red, is binned in approximately 4nm steps with a ±1nm tolerance per bin. The bins listed are H27 (613.5-617.0 nm), H28 (617.0-621.0 nm), H29 (621.0-625.0 nm), H30 (625.0-629.0 nm), and H31 (629.0-633.0 nm). The typical value of 624 nm falls within the H29 bin.

4. Performance Curve Analysis

The datasheet references typical characteristic curves which are essential for understanding device behavior under non-standard conditions. These typically include the relationship between forward current (I_F) and forward voltage (V_F), which shows the diode's exponential I-V characteristic. Another crucial curve depicts the relative luminous intensity versus ambient temperature, illustrating the negative temperature coefficient of light output common in LEDs—output decreases as temperature increases. A third standard curve shows the relative luminous intensity versus forward current, demonstrating how light output increases with current but may saturate or degrade at very high currents. The spectral distribution curve would show the intensity of light emitted across different wavelengths, centered around the 632 nm peak with the stated 20 nm half-width.

5. Mechanical and Packaging Information

The device conforms to the standard T-1 (3mm) round LED package dimensions. Key mechanical notes include: all dimensions are in millimeters (with inches in parentheses), with a general tolerance of ±0.25mm (0.010\") unless specified otherwise. The resin under the flange may protrude up to 1.0mm (0.04\") maximum. Lead spacing is measured at the point where the leads emerge from the package body, which is critical for PCB layout.

6. Soldering and Assembly Guidelines

Proper handling is critical to prevent damage. Leads must be formed at a point at least 3mm from the base of the LED lens, without using the lead frame base as a fulcrum. Forming must be done at room temperature and before soldering. During PCB assembly, minimal clinch force should be used. For soldering, a minimum clearance of 2mm must be maintained from the lens base to the solder point. The lens must never be immersed in solder. Recommended conditions are: for soldering iron, a maximum temperature of 300°C for no more than 3 seconds (one time only); for wave soldering, pre-heat to a maximum of 100°C for up to 60 seconds, followed by a solder wave at a maximum of 260°C for up to 10 seconds. Infrared (IR) reflow is explicitly stated as unsuitable for this through-hole type product. Excessive temperature or time can deform the lens or cause failure.

7. Packaging and Ordering Information

The standard packaging is as follows: LEDs are packed in bags containing 1000, 500, or 250 pieces. Ten of these bags are placed into an inner carton, totaling 10,000 pieces. Eight inner cartons are packed into an outer shipping carton, resulting in a total of 80,000 pieces per outer carton. It is noted that within a shipping lot, only the final pack may contain a non-full quantity. The specific part number is LTL42EKEKNN.

8. Application Recommendations

8.1 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness when multiple LEDs are connected in parallel, it is strongly recommended to use a current-limiting resistor in series with each individual LED (Circuit Model A). Driving multiple LEDs in parallel directly from a common voltage source with a single shared resistor (Circuit Model B) is discouraged, as slight variations in the forward voltage (V_F) characteristic between individual LEDs will cause significant differences in current and, consequently, brightness.

8.2 Electrostatic Discharge (ESD) Protection

The device is susceptible to damage from electrostatic discharge. Preventive measures must be implemented in the handling environment: operators should use grounded wrist straps or anti-static gloves; all equipment, machinery, and work surfaces must be properly grounded; storage racks should be conductive and grounded. An ion blower is recommended to neutralize static charge that may accumulate on the plastic lens due to friction during handling.

8.3 Storage and Cleaning

For storage, the ambient should not exceed 30°C or 70% relative humidity. LEDs removed from their original packaging should be used within three months. For longer-term storage outside the original pack, they should be kept in a sealed container with desiccant or in a nitrogen-desiccator. If cleaning is necessary, only alcohol-based solvents like isopropyl alcohol should be used.

9. Cautions and Application Limits

This LED is intended for ordinary electronic equipment. For applications requiring exceptional reliability where failure could jeopardize life or health—such as in aviation, transportation, medical systems, or safety devices—specific consultation and approval are required prior to use. This highlights the component's classification for commercial/industrial, not critical automotive or medical, grade applications.

10. Technical Comparison and Positioning

This AlInGaP-based red LED offers advantages over older technologies like GaAsP (Gallium Arsenide Phosphide), primarily in terms of higher luminous efficiency and better performance at elevated temperatures. The 22-degree viewing angle is standard for a non-diffused T-1 package, providing a directed beam suitable for panel indicators. The forward voltage of ~2.4V is compatible with common 3.3V and 5V logic supplies, requiring only a simple series resistor for operation. Its 75mW power dissipation rating is typical for a device of this size.

11. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED directly from a 5V supply?
A: No. You must use a series current-limiting resistor. For example, with a 5V supply, a typical V_F of 2.4V, and a desired I_F of 20mA, the resistor value would be R = (5V - 2.4V) / 0.02A = 130 Ohms. A standard 130 or 150 Ohm resistor would be suitable.

Q: Why is there a minimum luminous intensity specified?
A: Due to manufacturing variations, luminous intensity is binned. The minimum (310 mcd) and typical (880 mcd) values indicate the range. Designers should use the minimum value for worst-case brightness calculations to ensure the indicator is sufficiently visible under all conditions.

Q: What does the derating factor of 0.4 mA/°C mean?
A: For every degree Celsius the ambient temperature rises above 50°C, the maximum allowable continuous DC forward current decreases by 0.4 mA. At 75°C, the derating is (75-50)*0.4 = 10 mA, so the maximum allowed I_F would be 30 mA - 10 mA = 20 mA.

12. Practical Design and Usage Case

Scenario: Designing a status indicator panel with 10 uniformly bright red LEDs. The system uses a 5V rail. Based on the datasheet: 1) Select LEDs from the same luminous intensity bin (e.g., MN) for consistency. 2) Calculate the series resistor for each LED: R = (5V - 2.4V) / 0.02A = 130Ω. Use a 1/8W or 1/4W resistor. 3) On the PCB layout, ensure the holes for the LED leads are spaced according to the \"lead spacing... where leads emerge from package\" dimension. 4) Place the solder pads at least 2mm away from the LED body outline. 5) During assembly, instruct personnel to handle LEDs with ESD precautions, form leads (if needed) at >3mm from the body, and follow the specified wave soldering profile.

13. Operating Principle Introduction

Light is emitted through a process called electroluminescence. When a forward voltage exceeding the diode's junction potential (around 2.4V for this AlInGaP material) is applied, electrons from the n-type semiconductor and holes from the p-type semiconductor are injected across the p-n junction. These charge carriers recombine in the active region, releasing energy in the form of photons (light). The specific composition of the AlInGaP semiconductor alloy determines the bandgap energy, which directly corresponds to the wavelength (color) of the emitted light—in this case, red at approximately 624-632 nm. The water-clear epoxy lens shapes the light output beam.

14. Technology Trends and Context

While through-hole LEDs like this T-1 package remain widely used for prototyping, manual assembly, and applications requiring robust mechanical mounting, the industry trend has strongly shifted towards surface-mount device (SMD) packages (e.g., 0603, 0805, 1206, and PLCC types) for automated high-volume production. AlInGaP technology represents a mature and efficient solution for red, orange, and yellow LEDs, offering superior performance to older GaAsP. Current development focuses on increasing efficiency (lumens per watt), improving high-temperature performance, and enabling ever-smaller SMD packages with higher light output. This device sits within a well-established, reliable product category.