3.1mm Red LED Luminous Intensity 180-400mcd - Voltage 2.4V - Power 75mW - English Technical Document

1. Product Overview

This document details the specifications for a high-efficiency, low-power consumption red LED housed in a 3.1mm diameter through-hole package. The device utilizes an AlInGaP (Aluminum Indium Gallium Phosphide) chip as the light source, encapsulated within a transparent lens. It is designed for versatile mounting on printed circuit boards (PCBs) or panels and is characterized by its compatibility with integrated circuits due to low current requirements. The primary application targets include general-purpose indicator lights across various electronic equipment where reliable, visible signaling is required.

1.1 Core Advantages

• High Luminous Intensity: Delivers a typical output of 400 millicandelas (mcd) at a forward current of 20mA, ensuring high visibility.
• Energy Efficiency: Features low power dissipation and operates efficiently at standard drive currents.
• Compact and Versatile: The 3.1mm package allows for flexible integration into space-constrained designs.
• Driver Compatibility: Suitable for direct drive from low-current logic circuits, simplifying system design.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed.

• Power Dissipation (P_D): 75 mW maximum. This is the total power the LED package can handle, calculated as Forward Voltage (V_F) × Forward Current (I_F).
• Forward Current: A DC forward current (I_F) of 30 mA must not be exceeded. A higher peak forward current of 90 mA is permissible only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width).
• Thermal Derating: The maximum allowable DC forward current must be linearly reduced by 0.4 mA for every degree Celsius the ambient temperature (T_A) rises above 50°C.
• Reverse Voltage (V_R): 5 V. Exceeding this voltage in reverse bias can cause junction breakdown.
• Temperature Ranges: The device can operate from -40°C to +100°C and be stored from -55°C to +100°C.
• Soldering Temperature: Leads can withstand 260°C for 5 seconds when measured 1.6mm from the LED body.

2.2 Electrical & Optical Characteristics

These parameters are measured at an ambient temperature (T_A) of 25°C and define the device's typical performance.

• Luminous Intensity (I_V): Ranges from a minimum of 180 mcd to a typical 400 mcd at I_F = 20mA. Measurement follows the CIE photopic eye-response curve.
• Viewing Angle (2θ_1/2): 45 degrees. This is the full angle at which the light intensity drops to half of its peak axial value.
• Wavelength: The peak emission wavelength (λ_P) is typically 632 nm. The dominant wavelength (λ_d), which defines the perceived color, is typically 624 nm. The spectral bandwidth (Δλ) is 20 nm.
• Forward Voltage (V_F): Typically 2.4V, with a maximum of 2.4V at I_F = 20mA.
• Reverse Current (I_R): Maximum of 100 µA when a reverse voltage (V_R) of 5V is applied.
• Capacitance (C): Typically 40 pF measured at zero bias and 1MHz frequency.

3. Binning System Explanation

The LEDs are sorted into bins based on key optical parameters to ensure consistency within a production batch. The part number LTL1CHJETNN contains bin codes.

3.1 Luminous Intensity Binning

Units are in mcd measured at 20mA. The tolerance for each bin limit is ±15%.

• Bin HJ: 180 mcd (Min) to 310 mcd (Max). The part number indicates this LED is from the HJ bin.
• Bin KL: 310 mcd to 520 mcd.
• Bin MN: 520 mcd to 880 mcd.

3.2 Dominant Wavelength Binning

Units are in nm measured at 20mA. The tolerance for each bin limit is ±1nm. The part number does not specify a wavelength bin, so the device uses the typical value of 624 nm.

• Bin H27: 613.5 nm to 617.0 nm
• Bin H28: 617.0 nm to 621.0 nm
• Bin H29: 621.0 nm to 625.0 nm
• Bin H30: 625.0 nm to 629.0 nm
• Bin H31: 629.0 nm to 633.0 nm

4. Performance Curve Analysis

The datasheet references typical characteristic curves which would graphically illustrate the relationship between key parameters. These are essential for design.

• I-V Curve (Current vs. Voltage): Shows the exponential relationship between forward voltage and current. The typical V_F of 2.4V at 20mA is a point on this curve.
• Luminous Intensity vs. Forward Current: Demonstrates how light output increases with current, typically in a near-linear relationship within the operating range.
• Luminous Intensity vs. Ambient Temperature: Illustrates the decrease in light output as junction temperature rises, highlighting the importance of thermal management.
• Spectral Distribution: A plot of relative intensity versus wavelength, showing the peak at ~632 nm and the 20 nm half-width, confirming the pure red color.

5. Mechanical & Packaging Information

5.1 Package Dimensions

The LED is housed in a cylindrical package with a 3.1mm diameter. Key dimensional notes include:

• All dimensions are in millimeters (inches provided in parentheses).
• A general tolerance of ±0.25mm (±0.010\") applies unless specified otherwise.
• The maximum protrusion of resin under the flange is 1.0mm (0.04\").
• Lead spacing is measured at the point where leads exit the package body.

5.2 Polarity Identification

For through-hole LEDs, the longer lead typically denotes the anode (positive). The cathode (negative) is often indicated by a flat edge on the LED lens or a shorter lead. The datasheet diagram should be consulted for the specific polarity marking of this component.

6. Soldering & Assembly Guidelines

6.1 Lead Forming

• Bending must occur at least 3mm from the base of the LED lens.
• The base of the lead frame must not be used as a fulcrum.
• Forming must be done at room temperature and before the soldering process.
• Minimum clinch force should be used during PCB assembly to avoid mechanical stress.

6.2 Soldering Process

• Maintain a minimum clearance of 2mm from the lens base to the solder point.
• Avoid immersing the lens in solder.
• Do not stress the leads while the LED is hot from soldering.
• Recommended Soldering Conditions:
  • Soldering Iron: Max temperature 300°C, max time 3 seconds (one time only).
  • Wave Soldering: Pre-heat to max 100°C for max 60 sec; solder wave at max 260°C for max 10 sec.
• Warning: Excessive temperature or time can deform the lens or cause catastrophic failure.

6.3 Storage & Handling

• Storage: Recommended ambient not exceeding 30°C and 70% relative humidity.
• Shelf Life: LEDs removed from original packaging should be used within three months. For longer storage, use a sealed container with desiccant or a nitrogen ambient.
• Cleaning: Use alcohol-based solvents like isopropyl alcohol if necessary.

7. Packaging & Ordering Information

7.1 Packaging Specifications

The LEDs are packed in anti-static bags to prevent ESD damage.

• Packing Bag: 1000, 500, or 250 pieces per bag.
• Inner Carton: 10 packing bags, totaling 10,000 pieces.
• Outer Carton: 8 inner cartons, totaling 80,000 pieces per shipping lot. The last pack in a lot may not be full.

8. Application Design Recommendations

8.1 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness, especially when connecting multiple LEDs in parallel, a current-limiting resistor must be used in series with each LED.

• Recommended Circuit (Model A): Each LED has its own series resistor. This compensates for variations in the forward voltage (V_F) between individual LEDs, ensuring each receives the same current and thus emits the same brightness.
• Non-Recommended Circuit (Model B): Connecting multiple LEDs in parallel with a single shared resistor is discouraged. Small differences in V_F can cause significant current imbalance, leading to uneven brightness.

The series resistor value (R_S) is calculated using Ohm's Law: R_S = (V_Supply - V_F) / I_F. Using the typical V_F of 2.4V and a desired I_F of 20mA with a 5V supply: R_S = (5V - 2.4V) / 0.02A = 130 Ω. A standard 130Ω or 150Ω resistor would be suitable.

8.2 Electrostatic Discharge (ESD) Protection

The LED is sensitive to electrostatic discharge. Preventive measures are mandatory:

• Personnel must wear grounded wrist straps or anti-static gloves.
• All equipment, worktables, and storage racks must be properly grounded.
• Use an ionizer to neutralize static charge that may accumulate on the plastic lens.
• Implement a checklist for ESD certification of personnel and proper signage in work areas.

8.3 Application Scope & Cautions

This LED is intended for ordinary electronic equipment (office, communications, household). For applications where failure could jeopardize life or health (aviation, medical, safety systems), specific consultation and approval are required prior to use. This highlights the component's suitability for general-purpose indication but not for safety-critical roles without further qualification.

9. Technical Comparison & Differentiation

Compared to older technologies like GaAsP (Gallium Arsenide Phosphide) red LEDs, this AlInGaP device offers significantly higher luminous efficiency, resulting in brighter output at the same current. The 3.1mm package is a common industry standard, ensuring broad compatibility with existing PCB layouts and panel cutouts. The detailed binning system provides designers with predictable performance parameters, which is an advantage over unbinned or loosely specified components. The comprehensive set of application cautions (ESD, soldering, drive method) contained in this datasheet is a mark of a well-documented component aimed at ensuring reliability in the field.

10. Frequently Asked Questions (FAQs)

10.1 What resistor should I use with a 5V supply?

For a typical forward current of 20mA and forward voltage of 2.4V, use a 130Ω resistor. Always calculate based on your specific supply voltage and desired current.

10.2 Can I drive multiple LEDs with one resistor?

It is not recommended. Always use a separate current-limiting resistor for each LED when connecting in parallel to ensure uniform brightness.

10.3 Why is the viewing angle important?

The 45-degree viewing angle indicates a relatively focused beam. For wide-angle illumination, a diffused lens or a LED with a wider viewing angle (e.g., 120°) would be more suitable. This LED is ideal for directional indication.

10.4 How does temperature affect performance?

Luminous intensity decreases as temperature increases. For consistent brightness, consider thermal management if the LED operates in high ambient temperatures or at high currents. The derating factor of 0.4 mA/°C above 50°C must be applied.

11. Practical Design Case Study

Scenario: Designing a status indicator panel with ten identical red LEDs showing \"System Active.\"

Design Steps:

1. Power Supply: A regulated 5V DC rail is available.
2. Current Selection: Choose I_F = 20mA for good brightness within the 30mA maximum.
3. Circuit Topology: Connect all ten LEDs in parallel to the 5V rail.
4. Current Limiting: Place one 130Ω resistor in series with the anode of each individual LED.
5. Power Calculation: Power per LED: P = V_F × I_F ≈ 2.4V × 0.02A = 48mW, well below the 75mW maximum. Total current from supply: 10 × 20mA = 200mA.
6. Layout: Ensure 3mm lead bend radius and 2mm solder clearance during PCB design. Provide a common, robust ground plane.
7. Assembly: Follow the specified wave soldering profile to prevent thermal damage.

This approach guarantees uniform brightness across all indicators and reliable long-term operation.

12. Operating Principle

An LED is a semiconductor diode. When a forward voltage exceeding its junction potential (approximately 2.4V for this AlInGaP device) is applied, electrons and holes recombine within the active region of the semiconductor chip. This recombination process releases energy in the form of photons (light). The specific material composition of the semiconductor (AlInGaP) determines the wavelength (color) of the emitted light, which in this case is in the red spectrum (~624 nm dominant wavelength). The transparent epoxy lens serves to protect the semiconductor die, shape the light output beam (45° viewing angle), and enhance light extraction from the chip.

13. Technology Trends

The use of AlInGaP material represents an advancement over older LED technologies, offering higher efficiency and better temperature stability. The industry trend continues towards even higher efficiency materials and packages. While through-hole components like this 3.1mm LED remain vital for prototyping, repair, and certain applications requiring robust mechanical mounting, the broader market has shifted significantly towards surface-mount device (SMD) packages (e.g., 0603, 0805, 3528). SMD LEDs offer advantages in automated assembly, board space savings, and thermal management. However, through-hole LEDs maintain relevance in educational settings, hobbyist projects, and applications where manual soldering or high mechanical bond strength is preferred.