LTL307GC5D Green Diffused LED Datasheet - T-1 3/4 Package - 2.6V Max - 75mW - English Technical Document

1. Product Overview

The LTL307GC5D is a green, diffused LED designed for through-hole mounting on printed circuit boards (PCBs) or panels. It utilizes an AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material as its light source, which is known for producing efficient and bright green light. The device is housed in the popular and widely compatible T-1 3/4 package diameter, making it suitable for a broad range of indicator and illumination applications where a diffused, wide-angle light output is desired.

Key advantages of this product include its high luminous intensity output relative to its low power consumption, resulting in excellent efficiency. It is designed to be compatible with integrated circuits (ICs) due to its low current requirements. Furthermore, the product is manufactured to be environmentally friendly, being both lead (Pb) free and compliant with the RoHS (Restriction of Hazardous Substances) directive. It is also classified as a halogen-free product, with chlorine (Cl) and bromine (Br) content kept below specified limits (Cl < 900 ppm, Br < 900 ppm, Cl+Br < 1500 ppm).

2. Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. They are specified at an ambient temperature (T_A) of 25°C. Operation at or near these limits for extended periods is not recommended and will affect reliability.

• Power Dissipation (P_D): 75 mW. This is the maximum total power the device can safely dissipate as heat.
• Peak Forward Current (I_F(PEAK)): 60 mA. This maximum current is allowed only under pulsed conditions with a duty cycle of 1/10 and a pulse width of 0.1 ms.
• DC Forward Current (I_F): 20 mA. This is the maximum continuous forward current recommended for reliable operation.
• Operating Temperature Range: -40°C to +85°C. The device is rated to function within this ambient temperature span.
• Storage Temperature Range: -40°C to +100°C. The device can be stored within this range when not in operation.
• Lead Soldering Temperature: 265°C for 5 seconds. This rating applies when soldering the leads at a point 2.0 mm (0.078 inches) away from the LED body.

3. Electrical and Optical Characteristics

The following parameters are measured at an ambient temperature of 25°C and define the typical performance of the LED. The 'Typ.' column represents the expected value under standard test conditions, while 'Min.' and 'Max.' define the guaranteed limits.

3.1 Optical Characteristics

• Luminous Intensity (I_V): 20-85 mcd (Typ. 30 mcd) at I_F = 10 mA. This is the measure of perceived light power emitted. The guarantee includes a ±15% tolerance. Measurement is performed with a sensor and filter approximating the CIE photopic eye-response curve.
• Viewing Angle (2θ_1/2): 50 degrees (Typical). This is the full angle at which the luminous intensity drops to half of its axial (on-axis) value. The diffused lens contributes to this wide viewing angle.
• Peak Emission Wavelength (λ_P): 565 nm (Typical). This is the wavelength at which the spectral power distribution of the emitted light is at its maximum.
• Dominant Wavelength (λ_d): 572 nm (Typical) at I_F = 10 mA. This is derived from the CIE chromaticity diagram and represents the single wavelength that best defines the perceived color of the light.
• Spectral Line Half-Width (Δλ): 11 nm (Typical). This is the spectral bandwidth measured at half the maximum intensity (Full Width at Half Maximum - FWHM).

3.2 Electrical Characteristics

• Forward Voltage (V_F): 1.7 V to 2.6 V (Max.) at I_F = 20 mA. This is the voltage drop across the LED when operating at the specified current.
• Reverse Current (I_R): 100 μA (Max.) at V_R = 5 V. It is critical to note that this parameter is for test purposes only; the LED is not designed for operation under reverse bias. Applying reverse voltage in a circuit can damage the device.

4. Binning System Specifications

To ensure consistency in applications, LEDs are sorted (binned) based on their measured luminous intensity. The LTL307GC5D uses the following bin codes, defined at a test current of 10 mA. The tolerance for each bin limit is ±15%.

This binning allows designers to select LEDs with a specific brightness range for their application, aiding in achieving uniform appearance in multi-LED designs.

5. Packaging Specifications

The LEDs are supplied in industry-standard packaging for automated handling and inventory management.

• Primary Pack: 1000, 500, or 250 pieces per anti-static packing bag.
• Inner Carton: 8 packing bags are placed in one inner carton, totaling 8,000 pieces.
• Outer Carton (Shipping Carton): 8 inner cartons are packed into one outer carton, totaling 64,000 pieces.
• A note specifies that in every shipping lot, only the final pack may be a non-full pack.

6. Application and Handling Guidelines

6.1 Intended Use and Storage

This LED is intended for use in ordinary electronic equipment such as office equipment, communication devices, and household appliances. For applications requiring exceptional reliability where failure could jeopardize life or health (e.g., aviation, medical systems), specific consultation is required prior to use. For storage, the ambient should not exceed 30°C and 70% relative humidity. LEDs removed from their original packaging should ideally be used within three months. For longer storage outside the original pack, storage in a sealed container with desiccant or in a nitrogen ambient is recommended.

6.2 Cleaning and Mechanical Assembly

If cleaning is necessary, only alcohol-based solvents like isopropyl alcohol should be used. During lead forming, which must be done at room temperature and before soldering, the bend should be made at least 3 mm from the base of the LED lens. The base of the lead frame should not be used as a fulcrum. During PCB assembly, minimal clinch force should be applied to avoid mechanical stress on the LED package.

6.3 Soldering Process

A minimum clearance of 2 mm must be maintained between the base of the lens and the soldering point. The lens must never be dipped into solder. No external stress should be applied to the leads while the LED is hot from soldering. Recommended soldering conditions are:

• Soldering Iron: Maximum temperature 350°C, maximum time 3 seconds (one time only).
• Wave Soldering: Maximum pre-heat temperature 100°C for up to 60 seconds, followed by a solder wave at a maximum of 265°C for up to 5 seconds. Exceeding these temperature or time limits can cause lens deformation or catastrophic failure.

6.4 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 single current source (Circuit Model B) is not recommended, as slight variations in the forward voltage (V_F) characteristics between individual LEDs will cause significant differences in current sharing and, consequently, brightness.

6.5 Electrostatic Discharge (ESD) Protection

LEDs are susceptible to damage from electrostatic discharge. To prevent ESD damage during handling and assembly, the following practices are suggested: operators should wear conductive wrist straps or anti-static gloves; all equipment, machinery, and work surfaces must be properly grounded; and an ion blower can be used to neutralize static charge that may accumulate on the plastic lens. A checklist for maintaining a static-safe workstation is also implied, including verifying ESD certification for personnel and proper signage in work areas.

7. Performance Curve Analysis

The datasheet references typical performance curves which are essential for detailed design analysis. While the specific graphs are not provided in the text excerpt, they typically include:

• Relative Luminous Intensity vs. Forward Current: Shows how light output increases with drive current, often becoming sub-linear at higher currents due to heating effects.
• Forward Voltage vs. Forward Current: Illustrates the diode's I-V characteristic, crucial for selecting the appropriate series resistor value.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the decrease in light output as the junction temperature rises, a key factor for thermal management.
• Spectral Power Distribution: A graph showing the intensity of emitted light across different wavelengths, centered around the peak wavelength of 565 nm with a typical half-width of 11 nm.

Designers should consult these curves to understand device behavior under non-standard conditions (different currents, temperatures) and to optimize their application for efficiency and longevity.

8. Mechanical and Package Information

The LED uses a standard T-1 3/4 (5mm) radial leaded package. Key dimensional notes include: all dimensions are in millimeters (with inch equivalents); standard tolerance is ±0.25 mm unless noted otherwise; the maximum protrusion of resin under the flange is 0.6 mm; and lead spacing is measured at the point where the leads emerge from the package body. The exact dimensional drawing would provide critical measurements for PCB footprint design, including lead diameter, lens diameter and height, and seating plane details.

9. Technical Comparison and Application Scenarios

The LTL307GC5D's primary differentiators are its AlInGaP technology (offering high efficiency for green light), its diffused lens for wide viewing angle, and its compliance with modern environmental standards (RoHS, halogen-free). Compared to older technologies like GaP, AlInGaP provides higher brightness and efficiency. Typical application scenarios include status indicators on consumer electronics, panel indicators on industrial equipment, backlighting for legends on switches or panels, and general-purpose signaling where a soft, non-glaring green light is required. Its through-hole design makes it suitable for both automated and manual assembly processes.

10. Design Considerations and FAQs

Q: What resistor value should I use with a 5V supply?
A: Using the typical forward voltage (V_F) of ~2.1V at 10mA (for the 3Z bin), the resistor value R = (V_supply - V_F) / I_F = (5 - 2.1) / 0.01 = 290 Ω. A standard 300 Ω resistor would be appropriate. Always calculate based on your actual supply voltage and desired current.

Q: Can I drive this LED at 20mA continuously?
A: Yes, 20mA is the maximum recommended DC forward current. However, operating at the maximum current will generate more heat and may reduce lifetime. For optimal longevity and efficiency, driving at 10-15mA is often preferable.

Q: How does temperature affect performance?
A: As ambient temperature increases, the luminous intensity will decrease, and the forward voltage will typically drop slightly. For consistent brightness in high-temperature environments, thermal management or current compensation may be necessary.

Q: Why is a series resistor mandatory?
A> An LED's current-voltage relationship is exponential. A small increase in voltage causes a large increase in current. A series resistor provides negative feedback, stabilizing the current against variations in supply voltage and the LED's own forward voltage, which can vary from unit to unit and with temperature.

11. Operational Principles and Trends

The LTL307GC5D operates on the principle of electroluminescence in a semiconductor p-n junction. When a forward voltage is applied, electrons and holes are injected into the active region (the AlInGaP layer) where they recombine, releasing energy in the form of photons. The specific composition of the AlInGaP alloy determines the bandgap energy and thus the wavelength (color) of the emitted light, in this case, green. The diffused epoxy lens scatters the light, creating a wider, more uniform viewing angle compared to a clear lens. A trend in LED technology is the continuous improvement in luminous efficacy (lumens per watt), driven by advances in epitaxial growth, chip design, and package efficiency. There is also a strong industry-wide push towards higher reliability, tighter performance tolerances, and full compliance with environmental regulations.