LTL1CHKxKNN Series LED Lamp Datasheet - T-1 3mm Package - 2.0-2.4V Forward Voltage - 30mA Continuous Current - Hyper Red to Green Colors - English Technical Document

1. Product Overview

This document details the technical specifications for the LTL1CHKxKNN series of light-emitting diodes (LEDs). This product family consists of standard T-1 (3mm) through-hole LED lamps designed for general-purpose indicator applications requiring a higher level of luminous intensity. The devices are constructed using Aluminum Indium Gallium Phosphide (AlInGaP) material technology grown on a Gallium Arsenide (GaAs) substrate, which is known for producing high-efficiency visible light across a range of colors from red to green.

The core advantages of this series include low power consumption, high luminous efficiency, and compatibility with integrated circuit (IC) drive levels due to low current requirements. All variants in this series feature a water-clear lens, which does not diffuse the light, resulting in a more focused and intense beam suitable for clear indication.

The target market for these LEDs is broad, encompassing any electronic device requiring status indicators, panel lights, or simple illumination where reliability, visibility, and cost-effectiveness are key considerations.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

The absolute maximum ratings define the stress limits beyond which permanent damage to the device may occur. For reliable operation, these limits should never be exceeded, even momentarily.

• Power Dissipation (Pd): All devices in the series have a maximum power dissipation of 75 mW at an ambient temperature (T_A) of 25°C. Exceeding this limit can lead to overheating and catastrophic failure.
• Forward Current: Two current ratings are specified:
  • Continuous Forward Current (I_F): The maximum DC current that can be applied continuously is 30 mA for all colors.
  • Peak Forward Current: A higher pulsed current is allowed under specific conditions. For the red variants (Hyper Red, Super Red, Red), the peak current is 90 mA at a 1/10 duty cycle and 0.1ms pulse width. For the orange, yellow, and green variants, the peak current is 60 mA under the same conditions. This parameter is crucial for multiplexing or pulsed operation schemes.
• Thermal Derating: The maximum continuous forward current must be derated linearly above 70°C at a rate of 0.4 mA/°C. This means the allowable continuous current decreases as the ambient temperature increases, which is a critical design consideration for high-temperature environments.
• Reverse Voltage (V_R): The maximum allowable reverse voltage is 5V at a reverse current (I_R) of 100 µA. Applying a higher reverse voltage can break down the LED's PN junction.
• Temperature Ranges: The operating temperature range is from -40°C to +100°C, and the storage temperature range is from -55°C to +100°C, indicating robust performance across a wide range of conditions.
• Soldering Temperature: Leads can be soldered at 260°C for a maximum of 5 seconds, with the soldering point at least 1.6mm (0.063") away from the LED body to prevent thermal damage to the epoxy lens and internal die.

2.2 Electrical and Optical Characteristics

These parameters are measured under standard test conditions (T_A=25°C) and define the typical performance of the device.

• Luminous Intensity (I_v): This is a key optical parameter. All devices have a minimum luminous intensity of 140 mcd (millicandela) at a forward current (I_F) of 20mA. The typical values range from 210 mcd to 320 mcd depending on the specific color variant. The intensity is measured using a sensor and filter combination that approximates the photopic (human eye) response curve (CIE). The datasheet notes that products are classified into two luminous intensity ranks, with the rank code marked on the packaging.
• Viewing Angle (2θ_1/2): The series features a narrow viewing angle of 45 degrees. This is defined as the full angle at which the luminous intensity drops to half of its value measured on the central axis (0°). This characteristic results in a more directional beam of light.
• Wavelength Specifications: Three key wavelength metrics are provided:
  • Peak Wavelength (λ_P): The wavelength at which the optical power output is maximum. It ranges from 575 nm (Green) to 650 nm (Hyper Red).
  • Dominant Wavelength (λ_d): A single wavelength derived from the CIE chromaticity diagram that best represents the perceived color of the light. It is generally more relevant for color definition than peak wavelength. Values range from 572 nm (Green) to 639 nm (Hyper Red).
  • Spectral Line Half-Width (Δλ): The width of the emission spectrum at half of its maximum power (Full Width at Half Maximum - FWHM). It indicates the color purity. The red LEDs have a broader spectrum (20 nm), while the yellow and green LEDs have a narrower spectrum (15-17 nm).
• Forward Voltage (V_F): The voltage drop across the LED when driven at 20mA. The minimum V_F is between 2.0V and 2.05V, and the typical V_F is between 2.3V and 2.4V, depending on the color. This parameter is essential for designing the current-limiting resistor in series with the LED.
• Reverse Current (I_R): The leakage current when a reverse voltage of 5V is applied. It is typically 100 µA or less.
• Capacitance (C): The junction capacitance is typically 40 pF when measured at 0V bias and 1 MHz frequency. This can be a factor in high-speed switching applications.

3. Binning System Explanation

The datasheet indicates the use of a binning system primarily for luminous intensity. Products are classified into two intensity ranks (bins). The specific bin code for a given LED is marked on its individual packaging bag. This allows designers to select LEDs with consistent brightness levels for their applications. While not explicitly detailed for wavelength or forward voltage in this document, such parameters often have tolerance ranges (Min./Typ./Max.) that effectively define implicit bins.

4. Performance Curve Analysis

The datasheet references a page dedicated to "Typical Electrical / Optical Characteristics Curves." Although the specific graphs are not provided in the text, based on standard LED datasheets, these typically include:

• Relative Luminous Intensity vs. Forward Current (I-V Curve): Shows how light output increases with current, usually in a near-linear relationship within the operating range.
• Forward Voltage vs. Forward Current: Illustrates the diode's exponential V-I characteristic.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the decrease in light output as the junction temperature rises, highlighting the importance of thermal management.
• Spectral Distribution: A plot showing the relative power emitted across different wavelengths, visually representing the peak wavelength and spectral half-width.
• Viewing Angle Pattern: A polar plot showing the spatial distribution of light intensity around the LED.

These curves are invaluable for understanding the device's behavior under non-standard conditions and for precise circuit design.

5. Mechanical and Package Information

5.1 Package Dimensions

The LED uses a standard T-1 (3mm) radial through-hole package. Key dimensional notes include:

• All dimensions are in millimeters, with inches provided in parentheses.
• A standard tolerance of ±0.25mm (±0.010") applies unless otherwise specified.
• The resin under the flange may protrude up to a maximum of 1.0mm (0.04").
• Lead spacing is measured at the point where the leads exit the package body, which is critical for PCB hole placement.
• The package drawing (referenced as LTL1CHx Series) would typically show the overall length, lens diameter, lead length and diameter, and the position of the flat spot or other polarity indicator on the flange.

5.2 Polarity Identification

For through-hole LEDs, the longer lead is universally the anode (positive), and the shorter lead is the cathode (negative). Additionally, most packages have a flat spot on the rim of the flange, which is typically located on the cathode side. Always verify polarity before soldering to prevent reverse bias damage.

6. Soldering and Assembly Guidelines

The primary guideline provided is for hand or wave soldering: the soldering iron tip must be at least 1.6mm away from the plastic body of the LED, and the temperature must not exceed 260°C for more than 5 seconds. Prolonged heat can carbonize the epoxy lens, cause internal delamination, or damage the wire bonds.

General Assembly Notes:

• Avoid applying mechanical stress to the leads near the body.
• Do not clean the LED with ultrasonic cleaners, as cavitation can damage the internal structure.
• Use appropriate anti-static handling procedures during assembly to protect the semiconductor die from electrostatic discharge (ESD), although LEDs are generally more robust than some ICs.

7. Packaging and Ordering Information

The part numbering scheme for the series is LTL1CHKxKNN, where "x" denotes the color code:

• D: Hyper Red (AlInGaP)
• R: Super Red (AlInGaP)
• E: Red (AlInGaP)
• F: Yellow Orange (AlInGaP)
• Y: Amber Yellow (AlInGaP)
• S: Yellow (AlInGaP)
• G: Green (AlInGaP)

All variants share the water-clear lens and the same basic package. The specific packaging type (e.g., bulk, tape-and-reel) is not specified in the provided content but would be defined by the supplier.

8. Application Recommendations

8.1 Typical Application Scenarios

As general-purpose indicator lamps, these LEDs are suitable for:

• Power-on/status indicators on consumer electronics, appliances, and industrial control panels.
• Backlighting for switches, buttons, and legends.
• Simple decorative lighting.
• Basic opto-isolator or sensor applications (using the LED as the light source).

8.2 Design Considerations

• Current Limiting: An external current-limiting resistor is mandatory. Calculate the resistor value using Ohm's Law: R = (V_supply - V_F) / I_F. Always use the maximum V_F from the datasheet for a conservative design to ensure the current does not exceed the desired level.
• Thermal Management: For continuous operation near the maximum current rating or in high ambient temperatures, consider the derating curve. Ensure adequate airflow if multiple LEDs are used in a confined space.
• Viewing Angle: The 45° viewing angle creates a more focused hotspot. For wider area illumination, a diffused lens LED or an external diffuser would be more appropriate.
• Driving Circuits: The LEDs can be driven directly from microcontroller GPIO pins (which typically source/sink up to 20-25mA) or through transistor drivers for higher current or multiplexing many LEDs.

9. Technical Comparison and Differentiation

The key differentiator of the LTL1CHKxKNN series is its use of AlInGaP technology for colors from red to yellow/green. Compared to older technologies like GaAsP (Gallium Arsenide Phosphide), AlInGaP offers significantly higher luminous efficiency, meaning brighter light output for the same amount of electrical current. The water-clear lens provides the highest possible light output from the package, as no light is scattered or absorbed by a diffused tint. The narrow 45° viewing angle is a specific choice for applications requiring a directed beam rather than a wide, ambient glow.

10. Frequently Asked Questions (FAQ)

Q: Can I drive this LED directly from a 5V supply without a resistor?
A: No. Without a current-limiting resistor, the LED will attempt to draw excessive current, quickly exceeding its maximum ratings and leading to immediate failure. A series resistor is always required for constant-voltage drive.

Q: What is the difference between Peak Wavelength and Dominant Wavelength?
A: Peak Wavelength is where the most optical power is emitted. Dominant Wavelength is calculated from color coordinates and best matches the color perceived by the human eye. For monochromatic LEDs, they are often close, but Dominant Wavelength is the standard for specifying color.

Q: The LED gets warm during operation. Is this normal?
A: Yes, it is normal for an LED to generate heat. The efficiency is not 100%; some electrical power is converted to heat at the junction. This is why the derating specification and thermal considerations are important for long-term reliability.

Q: Can I use PWM (Pulse Width Modulation) to dim this LED?
A: Yes, these LEDs are well-suited for PWM dimming. You can drive them with the peak forward current (60mA or 90mA depending on color) at a low duty cycle to achieve an average current that dims the LED. Ensure the PWM frequency is high enough (typically >100Hz) to avoid visible flicker.

11. Practical Design and Usage Examples

Example 1: Microcontroller Status Indicator
A common use is as a power indicator. Connect the anode of a red LED (LTL1CHKEKNN) to a 3.3V microcontroller rail through a resistor. Calculate the resistor: Assuming V_F = 2.4V and desired I_F = 10mA (for lower power), R = (3.3V - 2.4V) / 0.01A = 90Ω. A standard 100Ω resistor would provide approximately 9mA, which is safe and sufficiently bright.

Example 2: 12V Panel Indicator
For a 12V automotive or industrial panel, the series resistor will dissipate more power. For a green LED (LTL1CHKGKNN) at 20mA: R = (12V - 2.4V) / 0.02A = 480Ω. The power in the resistor is P = I²R = (0.02)² * 480 = 0.192W. A standard 1/4W (0.25W) resistor is adequate but will run warm. Using a 1/2W resistor provides a better safety margin.

12. Technology Principle Introduction

These LEDs are based on a double heterojunction structure using Aluminum Indium Gallium Phosphide (AlInGaP) as the active light-emitting layer. When a forward voltage is applied, electrons and holes are injected into the active region from the N-type and P-type semiconductor layers, respectively. They recombine radiatively, releasing energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy of the material, which directly dictates the wavelength (color) of the emitted light. A wider bandgap produces shorter wavelengths (green/yellow), while a narrower bandgap produces longer wavelengths (red). The water-clear epoxy lens serves to protect the semiconductor die, shape the beam via its dome geometry, and provide a medium for efficient light extraction from the high-index semiconductor material.

13. Technology Development Trends

While this datasheet represents a mature and widely used product, LED technology continues to evolve. Trends relevant to this class of device include:

• Increased Efficiency: Ongoing material science and epitaxial growth improvements lead to higher lumens per watt (lm/W), meaning brighter light or lower power consumption for the same brightness.
• Color Consistency: Tighter binning tolerances for wavelength and luminous intensity are becoming standard, allowing for more uniform appearance in multi-LED applications.
• Packaging: While through-hole remains popular for prototyping and certain applications, surface-mount device (SMD) packages (like 0603, 0805) have largely become the industry standard for high-volume production due to their smaller size and suitability for automated assembly.
• Broadening Applications: The fundamental reliability and efficiency of LEDs like these continue to drive their adoption into new areas beyond simple indicators, such as in low-level general lighting, signage, and automotive interior lighting.