T-1 3/4 Bicolor LED Lamp Datasheet - 5.0mm Diameter - Red 2.4V / Green 2.6V - 75mW Power - English Technical Document

1. Product Overview

This document details the specifications for a bicolor, through-hole LED lamp in a standard T-1 3/4 package. The device integrates both red and green light-emitting chips within a single, water-clear epoxy lens, enabling the generation of two distinct colors from one component. It is designed for general indicator applications across a wide range of electronic equipment.

The core advantages of this LED include its compliance with lead-free (Pb-Free) and RoHS environmental standards, ensuring suitability for modern manufacturing requirements. The matched red and green chips are selected to provide uniform light output characteristics. Furthermore, the solid-state design offers long operational life and low power consumption, contributing to energy-efficient and reliable system design.

The target market encompasses applications in office automation equipment, communication devices, household appliances, and other consumer electronics where clear, reliable status indication is required.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

The device is characterized under an ambient temperature (T_A) of 25°C. The absolute maximum ratings define the limits beyond which permanent damage may occur. The power dissipation for both the red and green chips is rated at 75 mW. The peak forward current, applicable under pulsed conditions (1/10 duty cycle, 0.1ms pulse width), is 90 mA. The maximum continuous forward current is 30 mA for each chip. A derating factor of 0.57 mA/°C applies linearly from 50°C upwards, meaning the allowable continuous current decreases as temperature increases to prevent overheating.

The operating temperature range is specified from -40°C to +85°C, and the storage temperature range is from -55°C to +100°C, indicating robust performance in various environmental conditions. For assembly, the leads can withstand soldering at 260°C for a maximum of 5 seconds, provided the soldering point is at least 2.0 mm away from the LED body.

2.2 Electrical & Optical Characteristics

Key performance parameters are measured at T_A=25°C and a forward current (I_F) of 20 mA, which is the standard test condition.

Luminous Intensity (I_v): The light output is categorized into bins. For both red and green chips, the typical luminous intensity is 880 mcd, with minimum values starting at 520 mcd and maximum values reaching 1500 mcd. A tolerance of ±15% applies to the bin limits. Luminous intensity is measured using a sensor-filter combination that approximates the photopic (CIE) eye-response curve.

Viewing Angle (2θ_1/2): The viewing angle, defined as the full angle at which intensity drops to half its axial value, is 30 degrees for both colors. This indicates a relatively focused beam suitable for direct viewing.

Wavelength Characteristics:
- Peak Emission Wavelength (λ_p): Red: 650 nm, Green: 565 nm. This is the wavelength at which the spectral power distribution is highest.
- Dominant Wavelength (λ_d): Red: 634-644 nm (Typ. 639 nm), Green: 565-578 nm (Typ. 569 nm). This is the single wavelength perceived by the human eye, derived from the CIE chromaticity diagram.
- Spectral Line Half-Width (Δλ): Red: 20 nm, Green: 30 nm. This parameter describes the spectral purity or width of the emitted light.

Electrical Parameters:
- Forward Voltage (V_F): Red: 2.0-2.4 V (Typ. 2.4 V), Green: 2.1-2.6 V (Typ. 2.6 V).
- Reverse Current (I_R): Maximum 100 μA at a reverse voltage (V_R) of 5V. It is critical to note that the device is not designed for reverse operation; this test condition is for characterization only.

3. Binning System Explanation

The luminous intensity of the LEDs is sorted into bins to ensure consistency in application. The binning is identical for both the red and green chips.

• Bin Code M: 520 mcd (Min) to 680 mcd (Max)
• Bin Code N: 680 mcd (Min) to 880 mcd (Max)
• Bin Code P: 880 mcd (Min) to 1150 mcd (Max)
• Bin Code Q: 1150 mcd (Min) to 1500 mcd (Max)

The complete device is specified by a two-code combination: X-X (Luminous Intensity RED – Luminous Intensity GREEN). For example, a part marked \"N-P\" would have a red chip from Bin N (680-880 mcd) and a green chip from Bin P (880-1150 mcd). The tolerance for each bin limit is ±15%.

4. Performance Curve Analysis

While specific graphical data is referenced in the datasheet (e.g., Fig.1 for spectral distribution, Fig.5 for viewing angle), the typical curves would illustrate the following relationships essential for design:

I-V Curve: Shows the relationship between forward current (I_F) and forward voltage (V_F). For LEDs, this is an exponential curve. The specified V_F at 20mA provides a key operating point. Designers must use a series current-limiting resistor to set the operating current, as shown in the recommended drive circuit.

Luminous Intensity vs. Forward Current: Light output is generally proportional to forward current within the operating range. Operating above the absolute maximum ratings can lead to accelerated degradation or failure.

Luminous Intensity vs. Ambient Temperature: LED light output typically decreases as the junction temperature increases. The derating specification for forward current is directly linked to managing this thermal effect to maintain performance and reliability.

Spectral Distribution: The graphs for peak emission wavelength (λ_p) show the relative intensity of light across different wavelengths, confirming the dominant color and spectral width.

5. Mechanical & Package Information

The LED is housed in a T-1 3/4 package, which corresponds to a standard 5.0 mm diameter round lens. Key dimensional notes include:

• All dimensions are in millimeters, with a general tolerance of ±0.25mm unless specified otherwise.
• The resin under the flange may protrude by a maximum of 1.0mm.
• Lead spacing is measured at the point where the leads exit the package body.
• The polarity is typically indicated by the longer lead being the anode (+) and/or a flat spot on the lens rim near the cathode (-) lead. The specific pinout for the bicolor function (common anode or common cathode) must be verified from the package drawing referenced in the full datasheet.

6. Soldering & Assembly Guidelines

Proper handling is crucial for reliability.

Storage: LEDs should be stored in an environment not exceeding 30°C and 70% relative humidity. If removed from the original moisture-barrier bag, they should be used within three months. For longer storage, use a sealed container with desiccant or a nitrogen ambient.

Cleaning: Use only alcohol-based solvents like isopropyl alcohol if cleaning is necessary.

Lead Forming: Bending must be done at room temperature, before soldering. The bend should be at least 3mm from the base of the LED lens. Do not use the package body as a fulcrum.

PCB Assembly: Apply minimal clinching force to avoid mechanical stress on the leads.

Soldering:
- Maintain a minimum 2mm clearance from the lens base to the solder point.
- Never immerse the lens in solder.
- Avoid stress on leads during high-temperature soldering.
- Recommended Conditions:
  * Soldering Iron: Max 350°C for max 3 seconds (one time only).
  * Wave Soldering: Pre-heat ≤100°C for ≤60 sec, solder wave ≤260°C for ≤5 sec.
- Important: IR reflow soldering is NOT suitable for this through-hole type LED. Excessive heat or time can deform the lens or cause catastrophic failure.

7. Packaging & Ordering Information

The standard packaging flow is as follows:
- 500 or 200 pieces per anti-static packing bag.
- 10 packing bags are placed in an inner carton (total 5,000 pieces).
- 8 inner cartons are packed in an outer carton (total 40,000 pieces).
The specific part number for this device is LTL30EKDKGK.

8. Application Recommendations

8.1 Typical Application Scenarios

This bicolor LED is ideal for multi-status indicators. Common uses include power/standby indicators (red/green), fault/okay status lights, mode selection indicators on consumer electronics, and panel indicators on industrial control equipment. Its through-hole design makes it suitable for both prototype boards and products using traditional PCB assembly.

8.2 Design Considerations

Drive Circuit: LEDs are current-driven devices. To ensure uniform brightness, especially when connecting multiple LEDs in parallel, it is strongly recommended to use a dedicated current-limiting resistor in series with each LED (Circuit Model A). Using a single resistor for multiple parallel LEDs (Circuit Model B) is not advised due to variations in individual LED forward voltage (V_F), which can cause significant differences in current and, consequently, brightness.

ESD Protection: LEDs are sensitive to Electrostatic Discharge (ESD). Preventive measures during handling and assembly are mandatory:
- Use grounded wrist straps or anti-static gloves.
- Ensure all equipment, workstations, and storage racks are properly grounded.
- Use ionizers to neutralize static charges in the work area.

Thermal Management: Adhere to the power dissipation and current derating specifications. Ensure adequate spacing on the PCB and consider the operating environment to prevent the LED junction temperature from exceeding safe limits, which preserves luminous output and lifespan.

9. Technical Comparison & Differentiation

Compared to single-color LEDs, this bicolor device saves board space and simplifies assembly by combining two functions in one package. The use of AlInGaP (Aluminium Indium Gallium Phosphide) technology for both red and green chips offers advantages over older technologies like GaAsP, including higher efficiency, better temperature stability, and more consistent color purity. The matched chip performance ensures that the red and green outputs are well-balanced when driven under identical conditions. The T-1 3/4 package is an industry-standard size, ensuring broad compatibility with existing PCB layouts and panel cutouts.

10. Frequently Asked Questions (FAQs)

Q1: Can I drive the red and green chips simultaneously to create yellow/orange light?
A1: This datasheet does not specify characteristics for simultaneous operation. Mixing colors by driving both chips requires careful current control to achieve the desired hue and is subject to variations between individual LEDs. For dedicated multi-color or color-mixing applications, a dedicated RGB LED or a tri-color LED with characterized mixed-color specs would be more appropriate.

Q2: What is the difference between peak wavelength and dominant wavelength?
A2: Peak wavelength (λ_p) is the physical wavelength where the LED emits the most optical power. Dominant wavelength (λ_d) is a calculated value based on human color perception (CIE chart) that represents the \"pure\" color we see. For monochromatic LEDs like these, they are close but not identical; λ_d is the more relevant parameter for color specification.

Q3: Why is a series resistor necessary even if my power supply voltage matches the LED's V_F?
A3: The V_F is a typical value with a range. A small change in voltage can cause a large change in current due to the LED's exponential I-V curve. A series resistor makes the current much less sensitive to variations in supply voltage and V_F, providing stable and safe operation.

Q4: Can I use this LED for automotive interior lighting?
A4: This datasheet states the LED is for \"ordinary electronic equipment.\" Applications requiring exceptional reliability, such as automotive, aviation, or medical devices, require consultation with the manufacturer and likely a product qualified to specific automotive-grade standards (e.g., AEC-Q102). This standard product may not be suitable.

11. Practical Design Case Study

Scenario: Designing a dual-status indicator for a power supply unit. Green indicates \"Power On/Output OK,\" and red indicates \"Fault/Overload.\"

Implementation:
1. Circuit Design: Use a common-cathode configuration (verify from package drawing). Connect the two anodes (red and green) to microcontroller GPIO pins or logic circuits via separate current-limiting resistors. The common cathode connects to ground.
2. Resistor Calculation: Assuming a 5V supply (V_CC), target I_F = 20mA, and typical V_F of 2.4V (Red) and 2.6V (Green).
- R_red = (V_CC - V_{F_red}) / I_F = (5 - 2.4) / 0.02 = 130 Ω. Use a standard 130 Ω or 150 Ω resistor.
- R_green = (5 - 2.6) / 0.02 = 120 Ω. Use a standard 120 Ω resistor.
3. PCB Layout: Place the LED on the front panel. Ensure the holes for the leads match the specified lead spacing. Keep other heat-generating components away to avoid thermal impact on the LED's performance.
4. Software/Logic: Ensure the drive logic prevents both LEDs from being on continuously simultaneously if not desired, to manage power dissipation.

12. Operating Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light through electroluminescence. When a forward voltage is applied across the p-n junction, electrons from the n-type material recombine with holes from the p-type material in the active region. This recombination process releases energy in the form of photons (light). The specific wavelength (color) of the emitted light is determined by the energy bandgap of the semiconductor material used. In this device, AlInGaP (Aluminium Indium Gallium Phosphide) is used for both the red and green chips, with different material compositions yielding the different bandgaps required for red (~650 nm) and green (~565 nm) emission.

13. Technology Trends

The LED industry continues to evolve towards higher efficiency, greater reliability, and broader application. For indicator-type LEDs like this one, trends include:
- Miniaturization: Development of smaller package sizes (e.g., 3mm, 2mm, 1.6mm) while maintaining or improving light output.
- Enhanced Performance: Ongoing improvements in AlInGaP and InGaN (for blue/green/white) materials lead to higher luminous efficacy (more light per watt).
- Integration: Increased adoption of multi-chip packages (RGB, bi-color, tri-color) and even LEDs with integrated controllers (ICs) for smart lighting applications.
- Robustness: Improved packaging materials and designs for better resistance to moisture, thermal cycling, and mechanical stress, expanding into more demanding environments.
While through-hole LEDs remain vital for many applications, surface-mount device (SMD) LEDs dominate new designs due to their suitability for automated pick-and-place assembly, smaller footprint, and lower profile.