LTL307JGD Green Diffused LED Datasheet - T-1 3/4 Package - 2.4V Forward Voltage - 75mW Power Dissipation - English Technical Document

1. Product Overview

This document provides the complete technical specifications for a green, diffused LED component designed for through-hole mounting. The device utilizes AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology to produce green light. It is characterized by its popular T-1 3/4 package diameter, making it a versatile choice for a wide range of indicator and illumination applications on printed circuit boards (PCBs) or panels.

The core advantages of this component include high luminous intensity output, low power consumption, and high efficiency. It is designed to be compatible with integrated circuits (ICs) due to its low current requirements. Furthermore, the product is compliant with RoHS (Restriction of Hazardous Substances) directives, indicating it is a lead (Pb)-free component.

2. Technical Parameters Deep Objective Interpretation

2.1 Absolute Maximum Ratings

The absolute maximum ratings define the limits beyond which permanent damage to the device may occur. These ratings are specified at an ambient temperature (T_A) of 25°C and must not be exceeded under any operating conditions.

• Power Dissipation (P_D): 75 mW. This is the maximum amount of power the device can dissipate as heat.
• Peak Forward Current (I_F(PEAK)): 60 mA. This is the maximum allowable pulsed forward current, specified under a 1/10 duty cycle with a 0.1ms pulse width.
• DC Forward Current (I_F): 30 mA. This is the maximum continuous forward current the LED can handle.
• Derating: The DC forward current must be linearly derated by 0.4 mA for every degree Celsius above 50°C ambient temperature.
• Reverse Voltage (V_R): 5 V. Applying a reverse voltage exceeding this value can damage the LED's PN junction.
• Operating Temperature Range: -40°C to +100°C. The ambient temperature range within which the device is designed to function.
• Storage Temperature Range: -55°C to +100°C.
• Lead Soldering Temperature: 260°C for 5 seconds, measured 2.0 mm (0.078 inches) from the LED body.

2.2 Electrical and Optical Characteristics

The electrical and optical characteristics are measured at T_A=25°C and represent the typical performance parameters of the device.

• Luminous Intensity (I_V): 65 mcd (Min), 110 mcd (Typ) at a forward current (I_F) of 20 mA. The guarantee includes a ±15% tolerance. This parameter is measured using a sensor and filter approximating the CIE photopic eye-response curve.
• Viewing Angle (2θ_1/2): 50 degrees (Typ). This is the full angle at which the luminous intensity drops to half of its axial (on-axis) value, characteristic of a diffused lens which spreads the light.
• Peak Emission Wavelength (λ_P): 575 nm (Typ). The wavelength at which the optical power output is maximum.
• Dominant Wavelength (λ_d): 572 nm (Typ). This is the single wavelength perceived by the human eye that defines the color of the LED, derived from the CIE chromaticity diagram.
• Spectral Line Half-Width (Δλ): 11 nm (Typ). The spectral width of the emitted light at half its maximum power (Full Width at Half Maximum - FWHM).
• Forward Voltage (V_F): 2.1 V (Min), 2.4 V (Typ) at I_F = 20 mA.
• Reverse Current (I_R): 100 µA (Max) at a reverse voltage (V_R) of 5 V.
• Capacitance (C): 40 pF (Typ) measured at zero bias (V_F=0) and a frequency of 1 MHz.

3. Binning System Explanation

The LEDs are sorted into bins based on key optical parameters to ensure consistency within a production batch. Two primary binning criteria are defined.

3.1 Luminous Intensity Binning

LEDs are categorized by their luminous intensity measured at 20 mA. The bin code, tolerance, and range are as follows:

• Code D: 65 mcd (Min) to 85 mcd (Max)
• Code E: 85 mcd (Min) to 110 mcd (Max)
• Code F: 110 mcd (Min) to 140 mcd (Max)
• Code G: 140 mcd (Min) to 180 mcd (Max)

Note: Tolerance on each bin limit is ±15%.

3.2 Dominant Wavelength Binning

LEDs are also binned by their dominant wavelength to control color consistency. The bins are defined in 2 nm steps.

• Code H06: 566.0 nm to 568.0 nm
• Code H07: 568.0 nm to 570.0 nm
• Code H08: 570.0 nm to 572.0 nm
• Code H09: 572.0 nm to 574.0 nm
• Code H10: 574.0 nm to 576.0 nm
• Code H11: 576.0 nm to 578.0 nm

Note: Tolerance on each bin limit is ±1 nm. The specific part number LTL307JGD would correspond to a specific combination of intensity and wavelength bins.

4. Performance Curve Analysis

The datasheet references typical electrical and optical characteristic curves. While the specific graphs are not detailed in the provided text, they typically include the following essential plots for design analysis:

• Relative Luminous Intensity vs. Forward Current (I_V vs. I_F): Shows how light output increases with current, crucial for setting drive current for desired brightness.
• Forward Voltage vs. Forward Current (V_F vs. I_F): The I-V characteristic curve of the diode, important for calculating series resistor values and power dissipation.
• Relative Luminous Intensity vs. Ambient Temperature (I_V vs. T_A): Illustrates how light output decreases as junction temperature rises, highlighting the importance of thermal management.
• Spectral Distribution: A graph of relative intensity versus wavelength, showing the peak at ~575 nm and the spectral width (FWHM) of ~11 nm.
• Viewing Angle Pattern: A polar plot showing the angular distribution of light intensity, confirming the 50-degree viewing angle for the diffused lens.

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

5. Mechanical and Packaging Information

5.1 Package Dimensions

The device uses the industry-standard T-1 3/4 (5mm) round through-hole package. Key dimensional notes include:

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

The specific dimensional drawing would provide exact values for body diameter, lens height, lead length, and lead diameter.

5.2 Polarity Identification

For through-hole LEDs, polarity is typically indicated by two features: lead length and internal structure. The longer lead is the anode (positive), and the shorter lead is the cathode (negative). Additionally, many packages have a flat spot on the rim of the lens or a chamfer on the cathode side of the flange. Observing both indicators is recommended for correct orientation.

6. Soldering and Assembly Guidelines

Proper handling is critical to prevent damage during assembly.

6.1 Lead Forming

• Bending must be performed at a point at least 3 mm from the base of the LED lens.
• The base of the lead frame must not be used as a fulcrum.
• Lead forming must be done at room temperature and before the soldering process.
• During PCB insertion, use the minimum clinch force necessary to avoid imposing excessive mechanical stress on the leads or package.

6.2 Soldering Process

• Maintain a minimum clearance of 2 mm between the base of the lens and the solder point. The lens must never be immersed in solder.
• Avoid applying any external stress to the leads while the LED is at elevated temperature post-soldering.
• Recommended Soldering Conditions:
  • Hand Soldering (Iron): Maximum temperature 300°C, maximum time 3 seconds per lead (one-time soldering only).
  • Wave Soldering: Maximum pre-heat temperature 100°C for up to 60 seconds. Solder wave temperature maximum 260°C for a maximum of 5 seconds.

Warning: Exceeding these temperature or time limits can cause lens deformation, internal wire bond failure, or degradation of the epoxy material, leading to catastrophic device failure.

6.3 Cleaning and Storage

• Cleaning: If necessary, clean only with alcohol-based solvents such as isopropyl alcohol.
• Storage: For long-term storage outside the original packaging, store in a sealed container with desiccant or in a nitrogen ambient. The recommended storage environment does not exceed 30°C or 70% relative humidity. Components removed from their original packaging should ideally be used within three months.

7. Packaging and Ordering Information

The standard packaging flow is as follows:

1. Basic Unit: 500 pieces or 250 pieces per anti-static packing bag.
2. Inner Carton: 10 packing bags are placed into one inner carton, totaling 5,000 pieces.
3. Outer Carton (Shipping Carton): 8 inner cartons are packed into one outer carton, totaling 40,000 pieces.

A note specifies that within any given shipping lot, only the final pack may contain a non-full quantity. The part number LTL307JGD follows a manufacturer-specific coding system where "LTL" likely denotes the product family, "307" may indicate the color and package, and "JGD" specifies the performance bin codes for luminous intensity and dominant wavelength.

8. Application Recommendations

8.1 Typical Application Scenarios

This green diffused LED is suitable for a wide array of applications requiring a clear, visible indicator, including but not limited to:

• Power status indicators on consumer electronics, appliances, and industrial equipment.
• Signal and mode indicators on communication devices, audio/video equipment, and control panels.
• Backlighting for switches, legends, and small panels.
• General purpose indicator lights in automotive interiors, instrumentation, and hobbyist projects.

The datasheet explicitly states these LEDs are intended for ordinary electronic equipment (office equipment, communication equipment, household applications). For applications requiring exceptional reliability where failure could jeopardize life or health (aviation, medical devices, safety systems), consultation with the manufacturer is required prior to use.

8.2 Drive Circuit Design

LEDs are current-driven devices. A critical design rule is to always use a current-limiting resistor in series with the LED.

• Recommended Circuit (Circuit A): Each LED has its own dedicated series resistor. This ensures uniform brightness by compensating for the natural variation in forward voltage (V_F) from one LED to another, even when they are of the same type and bin.
• Non-Recommended Circuit (Circuit B): Connecting multiple LEDs in parallel with a single shared current-limiting resistor. Small differences in the I-V characteristics of each LED will cause current to divide unevenly, leading to significant differences in brightness between the devices.

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 20 mA with a 5V supply: R_S = (5V - 2.4V) / 0.020A = 130 Ω. A standard 130 Ω or 150 Ω resistor would be appropriate, also ensuring power rating is sufficient (P = I²R ≈ 0.052W).

8.3 Electrostatic Discharge (ESD) Protection

The LED is susceptible to damage from electrostatic discharge. Mandatory precautions include:

• Personnel must wear grounded wrist straps or anti-static gloves when handling LEDs.
• All equipment, workbenches, and storage racks must be properly grounded.
• Use ionizers to neutralize static charge that can build up on the plastic lens surface due to friction during handling.
• Maintain a static-safe workstation with certified materials and monitor training/certification for all personnel.

9. Technical Comparison and Differentiation

Within the category of 5mm green through-hole LEDs, this AlInGaP-based device offers distinct advantages:

• vs. Traditional Green GaP LEDs: AlInGaP technology typically offers significantly higher luminous efficiency and intensity compared to older Gallium Phosphide (GaP) green LEDs, resulting in brighter output at the same drive current.
• vs. Non-Diffused (Water Clear) LEDs: The diffused lens provides a wider, more uniform viewing angle (50° vs. a narrower beam for clear lenses), making it ideal for applications where the indicator needs to be visible from a broad range of angles.
• vs. Super-Bright LEDs: This device occupies a mid-range performance segment. It offers good brightness (65-180 mcd bins) suitable for most indicator purposes without the extreme drive current requirements or cost of ultra-high-brightness LEDs, balancing performance and power consumption effectively.
• RoHS Compliance: As a lead-free product, it meets modern environmental regulations for electronic manufacturing, which is a key differentiator from non-compliant legacy components.

10. Frequently Asked Questions (Based on Technical Parameters)

1. Q: What resistor should I use with a 5V supply?
   A: For a typical forward current of 20 mA and V_F of 2.4V, use a 130 Ω resistor. Always calculate based on your specific supply voltage and desired current.
2. Q: Can I drive this LED directly from a microcontroller pin?
   A: Yes, but you must still use a series current-limiting resistor. The microcontroller pin acts as the voltage source. Ensure the pin can source or sink the required 20 mA current.
3. Q: Why is there a ±15% tolerance on the luminous intensity even within a bin?
   A: Semiconductor manufacturing has inherent process variations. Binning groups LEDs with similar performance, but a tolerance range accounts for measurement accuracy and minor performance spreads within the group to guarantee a minimum performance level.
4. Q: What happens if I exceed the absolute maximum DC forward current of 30 mA?
   A: Exceeding this rating increases the junction temperature beyond safe limits, which can accelerate light output degradation (lumen depreciation) and significantly shorten the operational lifespan, potentially causing immediate catastrophic failure.
5. Q: How critical is the 2mm soldering clearance from the lens?
   A: Very critical. Solder heat conducted up the lead can soften or melt the epoxy lens, causing deformation or allowing moisture ingress, which will damage the LED.

11. Practical Design and Usage Case

Case: Designing a Multi-LED Status Panel
An engineer is designing a control panel with four green status indicators. Using a common 5V rail, they need consistent brightness.

Solution: Implement the recommended Circuit A. Use four identical current-limiting resistors, one in series with each LTL307JGD LED. Even if the LEDs come from different bins or have slight V_F variations, the individual resistors will regulate the current through each one independently, ensuring all four indicators have matched, uniform brightness. The 50° viewing angle of the diffused lens ensures the status is clearly visible to an operator standing in front of or slightly to the side of the panel. The designer must ensure the PCB layout maintains the minimum 2mm solder pad distance from the LED body and provides adequate spacing for heat dissipation, especially if the LEDs are to be driven continuously at or near the maximum current.

12. Principle Introduction

This LED operates on the principle of electroluminescence in a semiconductor diode. The active region is composed of AlInGaP (Aluminum Indium Gallium Phosphide) layers grown on a substrate. When a forward voltage exceeding the diode's turn-on voltage (~2.1V) is applied, electrons and holes are injected into the active region from the N-type and P-type semiconductor layers, respectively. These charge carriers recombine, releasing energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy of the semiconductor, which directly defines the wavelength (color) of the emitted light—in this case, green at a dominant wavelength of ~572 nm. The diffused epoxy lens contains scattering particles that randomize the direction of the emitted photons, broadening the beam into a wide viewing angle compared to a clear lens which would produce a more focused beam.

13. Development Trends

The evolution of indicator LEDs like this one follows several key industry trends:

• Increased Efficiency: Ongoing material science and epitaxial growth improvements continue to push the luminous efficacy (lumens per watt) of AlInGaP and other LED technologies higher, allowing for brighter output at lower currents or reduced power consumption for the same brightness.
• Miniaturization: While the T-1 3/4 package remains popular for through-hole applications, there is a strong market shift towards surface-mount device (SMD) packages (e.g., 0603, 0402) for higher density PCB assembly. Through-hole components are often retained for prototyping, hobbyist use, or applications requiring higher mechanical robustness.
• Color Consistency and Binning: Manufacturing processes are becoming more precise, leading to tighter binning distributions. Some high-volume applications may demand "pre-binned" or "matched" LEDs with extremely narrow wavelength and intensity tolerances.
• Integration: A trend exists towards integrating the current-limiting resistor, ESD protection diode, or even a control IC directly into the LED package, creating "smart" or "easy-drive" LED components that simplify circuit design.
• Sustainability: The drive for RoHS compliance and halogen-free materials is now standard. Future trends may include increased use of recyclable materials in packaging and further reduction of other hazardous substances.