LTL17KGH5D Green LED Lamp Datasheet - T-1 (3mm) Package - 2.4V Forward Voltage - 30mA DC Current - 75mW Power Dissipation - English Technical Document

1. Product Overview

This document provides the complete technical specifications for a green through-hole LED lamp. The device is designed for status indication and signaling applications across a wide range of electronic equipment. It is offered in the popular T-1 (3mm) diameter package, providing a common form factor for easy integration into existing designs.

The core advantages of this LED include its low power consumption and high efficiency, making it suitable for both battery-powered and line-operated devices. It is constructed with lead-free materials and is compliant with RoHS environmental directives. The device features a green diffused lens which helps to broaden the viewing angle and soften the light output for indicator purposes.

The target markets for this component are broad, encompassing communication equipment, computer peripherals, consumer electronics, home appliances, and industrial control systems. Its reliability and standard package make it a versatile choice for designers requiring a dependable visual indicator.

2. Technical Parameter Deep Dive

2.1 Absolute Maximum Ratings

The device is specified for operation within strict environmental and electrical limits to ensure long-term reliability. The absolute maximum ratings define the thresholds beyond which permanent damage may occur.

• Power Dissipation (P_D): 75 mW maximum. This is the total power the device can safely dissipate as heat, calculated from the forward voltage and current.
• Peak Forward Current (I_FP): 90 mA maximum. This rating applies only under pulsed conditions with a duty cycle of 10% or less and a pulse width not exceeding 10 microseconds. It is useful for brief, high-brightness flashes.
• DC Forward Current (I_F): 30 mA maximum. This is the recommended maximum continuous current for normal operation. Exceeding this value can lead to accelerated lumen depreciation and reduced lifespan.
• Operating Temperature Range (T_opr): -40°C to +85°C. The device is rated for reliable operation across this wide industrial temperature range.
• Storage Temperature Range (T_stg): -40°C to +100°C.
• Lead Soldering Temperature: 260°C for a maximum of 5 seconds, measured at a point 2.0mm (0.079 inches) from the epoxy body. This rating is critical for wave or hand soldering processes.

2.2 Electrical & Optical Characteristics

These parameters are measured at a standard ambient temperature (T_A) of 25°C and define the typical performance of the LED.

• Luminous Intensity (I_V): 110 (Min), 180 (Typ), 520 (Max) mcd at I_F = 20mA. The intensity is measured using a sensor filtered to match the photopic (CIE) eye-response curve. A ±15% testing tolerance is applied to the bin limits.
• Viewing Angle (2θ_1/2): 50 degrees (Typical). This is the full angle at which the luminous intensity drops to half of its peak (on-axis) value. The diffused lens contributes to this relatively wide viewing angle.
• Peak Emission Wavelength (λ_P): 574 nm (Typical). This is the wavelength at which the spectral power distribution reaches its maximum.
• Dominant Wavelength (λ_d): 566 (Min), 571 (Typ), 578 (Max) nm. 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 (Typical). This indicates the spectral purity, measuring the width of the emission spectrum at half its maximum power.
• Forward Voltage (V_F): 2.1 (Min), 2.4 (Typ) Volts at I_F = 20mA. Designers must account for this voltage drop when calculating series current-limiting resistors.
• Reverse Current (I_R): 100 μA maximum at V_R = 5V. It is crucial to note that this device is not designed for reverse-bias operation; this test condition is for characterization only.

3. Binning System Specification

To ensure color and brightness consistency in production, LEDs are sorted into bins based on key parameters. This allows designers to select parts that meet specific application requirements.

3.1 Luminous Intensity Binning

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

• Bin FG: Minimum 110 mcd, Maximum 180 mcd.
• Bin HJ: Minimum 180 mcd, Maximum 310 mcd.
• Bin KL: Minimum 310 mcd, Maximum 520 mcd.

The intensity classification code is marked on each packing bag for traceability.

3.2 Dominant Wavelength Binning

Units are in nanometers (nm) measured at 20mA. The tolerance for each bin limit is ±1 nm. This tight control ensures a consistent shade of green across a production run.

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

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (Typical Electrical/Optical Characteristics Curves on page 4/9), the following analysis is based on standard LED behavior and the provided parameters.

4.1 Forward Current vs. Forward Voltage (I-V Curve)

The typical forward voltage of 2.4V at 20mA indicates this is a standard efficiency GaP or similar material-based green LED. The I-V relationship is exponential. Operating the LED at currents significantly below 20mA will result in a lower forward voltage and reduced light output. Exceeding the maximum DC current will cause the voltage to rise more sharply, generating excessive heat.

4.2 Luminous Intensity vs. Forward Current

Luminous intensity is approximately proportional to the forward current in the normal operating range (e.g., up to 30mA). However, efficiency (lumens per watt) often peaks at a current lower than the maximum rating. Driving the LED at 20mA, as used for testing, is a common operating point that balances brightness and longevity.

4.3 Spectral Distribution

With a peak wavelength of 574nm and a dominant wavelength in the 571nm range, this LED emits in the pure green region of the visible spectrum. The spectral half-width of 11nm is characteristic of a standard green LED, providing a saturated color suitable for indicators.

4.4 Temperature Characteristics

Like all LEDs, the performance of this device is temperature-dependent. Typically, the forward voltage decreases with increasing junction temperature (negative temperature coefficient), while the luminous intensity also decreases. The wide operating temperature range of -40°C to +85°C ensures functionality in harsh environments, but designers should note that light output at temperature extremes will be lower than at 25°C.

5. Mechanical & Packaging Information

5.1 Outline Dimensions

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

• All dimensions are in millimeters, with tolerances of ±0.25mm unless otherwise specified.
• A maximum protrusion of resin under the flange of 1.0mm is allowed.
• Lead spacing is measured at the point where the leads emerge from the package body.
• The physical drawing (referenced on page 2/9 of the datasheet) provides the complete dimensional details for PCB layout.

5.2 Polarity Identification

For through-hole LEDs, the cathode is typically identified by a flat spot on the lens rim, a shorter lead, or other marking. The specific identification method should be confirmed from the package outline drawing. Correct polarity is essential; applying reverse voltage exceeding 5V can damage the device.

5.3 Packaging Specifications

The LEDs are supplied in anti-static packing bags. Standard packing quantities are:

• Packing Bag: 1000, 500, 200, or 100 pieces.
• Inner Carton: Contains 10 packing bags, totaling 10,000 pieces.
• Outer Carton: Contains 8 inner cartons, totaling 80,000 pieces.

It is noted that within a shipping lot, only the final pack may be a non-full pack.

6. Soldering & Assembly Guidelines

6.1 Storage Conditions

For optimal shelf life, LEDs should be stored in an environment not exceeding 30°C and 70% relative humidity. If removed from their original moisture-barrier bags, it is recommended to use them within three months. For longer-term storage outside the original packaging, they should be kept in a sealed container with desiccant or in a nitrogen-purged desiccator to prevent moisture absorption, which can cause "popcorning" during soldering.

6.2 Lead Forming

If leads need to be bent, this must be done before soldering and at room temperature. The bend should be made at a point at least 3mm away from the base of the LED lens. The base of the lead frame must not be used as a fulcrum, as this can stress the internal wire bonds. During PCB insertion, use the minimum clinch force necessary to avoid mechanical stress on the package.

6.3 Soldering Process

A minimum clearance of 2.0mm must be maintained between the base of the epoxy lens and the solder point. Dipping the lens into molten solder must be avoided.

Recommended Soldering Conditions:

• Soldering Iron: Maximum temperature 350°C, for a maximum of 3 seconds per lead (one time only).
• Wave Soldering:
  • Pre-heat: Maximum 100°C for up to 60 seconds.
  • Solder Wave: Maximum 260°C.
  • Soldering Time: Maximum 5 seconds.
  • Dipping Position: No lower than 2.0mm from the base of the epoxy bulb.

Critical Warning: Excessive soldering temperature or time can cause the epoxy lens to deform (melt) or lead to catastrophic failure of the LED chip. Infrared (IR) reflow soldering is explicitly stated as not suitable for this through-hole type LED product.

6.4 Cleaning

If cleaning is required after soldering, only alcohol-based solvents such as isopropyl alcohol (IPA) should be used. Harsh or aggressive chemicals may damage the epoxy lens.

7. Application & Design Recommendations

7.1 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness when driving multiple LEDs, especially in parallel, it is strongly recommended to use a individual current-limiting resistor in series with each LED (Circuit Model A).

Avoid connecting multiple LEDs directly in parallel without individual resistors (Circuit Model B). Small variations in the forward voltage (V_F) characteristic from one LED to another can cause significant current imbalance, leading to uneven brightness and potential over-current in one device while others are under-driven.

The series resistor value (R_S) can be calculated using Ohm's Law: R_S = (V_Supply - V_F) / I_F. Use the typical or maximum V_F from the datasheet for a conservative design. For example, with a 5V supply, a target I_F of 20mA, and a V_F of 2.4V: R_S = (5V - 2.4V) / 0.020A = 130 Ohms. A standard 130Ω or 150Ω resistor would be appropriate, also considering the resistor's power rating (P = I²R).

7.2 Electrostatic Discharge (ESD) Protection

The LED is susceptible to damage from electrostatic discharge. The following precautions must be observed during handling and assembly:

• Personnel should wear a grounded wrist strap or anti-static gloves.
• All equipment, workbenches, and storage racks must be properly grounded.
• Use an ionizer to neutralize static charge that may build up on the plastic lens due to friction during handling.
• Implement an ESD control program with training, certification, and regular checks of workstations (ensuring surfaces measure less than 100V).

7.3 Thermal Management

While the power dissipation is low (75mW max), proper thermal design extends LED life. Avoid operating at the absolute maximum current and temperature simultaneously. Ensure the PCB layout does not trap heat around the LED body, especially if it is part of a densely packed array.

8. Typical Application Scenarios

This green LED is well-suited for a multitude of status indication applications:

• Power/Status Indicators: On/Off, standby, or operational status on devices like routers, chargers, and power supplies.
• Equipment Panel Indicators: Signal presence, mode selection, or fault warnings on industrial control panels, test equipment, and audio gear.
• Consumer Electronics: Backlighting for buttons, status lights on appliances, or decorative lighting in toys.
• Automotive Interior Indicators: For non-critical interior lighting where specifications meet the environmental requirements.
• Signage & Displays: As individual pixels or indicators in low-resolution informational displays.

9. Frequently Asked Questions (FAQ)

9.1 Can I drive this LED without a series resistor?

No. An LED must be driven with a current-limited source. Connecting it directly to a voltage source like a battery or power supply will cause excessive current to flow, rapidly destroying the device. A series resistor is the simplest form of current limiting.

9.2 What is the difference between Peak Wavelength and Dominant Wavelength?

Peak Wavelength (λ_P) is the literal wavelength where the LED emits the most optical power. Dominant Wavelength (λ_d) is a calculated value that corresponds to the perceived color by the human eye on the CIE chromaticity chart. For monochromatic LEDs like this green one, they are often close, but λ_d is the more relevant parameter for color specification.

9.3 Why is there a minimum soldering distance (2.0mm) from the lens?

This distance is critical to prevent thermal shock and heat damage to the epoxy lens and the internal die attach material. Solder heat conducted up the lead can melt the epoxy or weaken the internal bonds if it reaches the package body.

9.4 How do I interpret the luminous intensity bin codes (FG, HJ, KL)?

These codes represent sorted groups based on measured light output. For consistent brightness in an application, specify and use LEDs from the same intensity bin. For example, if your design requires higher brightness, you would specify Bin KL parts. The bin code is marked on the packaging for identification.

10. Design Case Study: Multi-LED Status Panel

Scenario: Designing a control panel with 10 green status indicators, each independently controlled by a 5V microcontroller GPIO pin.

Design Steps:

1. Current Selection: Choose a drive current of 20mA for good brightness within the device's linear range.
2. Resistor Calculation: Using the typical V_F of 2.4V and a 5V supply: R = (5V - 2.4V) / 0.020A = 130Ω. A standard 130Ω 1/4W resistor is selected.
3. Circuit Topology: Each LED has its own 130Ω resistor connected in series between the microcontroller pin and the LED anode. The LED cathodes are connected to ground. This is the recommended "Circuit A" from the datasheet, implemented 10 times.
4. Microcontroller Consideration: Verify that the microcontroller's GPIO pins can source or sink the total required current (10 * 20mA = 200mA). If not, use transistor drivers.
5. PCB Layout: Place the resistor close to the LED's anode lead. Maintain the 2.0mm clearance from the LED body for any solder pads or traces. Ensure the LEDs are spaced to allow adequate heat dissipation.
6. Part Selection: Specify LEDs from a single Dominant Wavelength bin (e.g., H08 for 570-572nm) and a single Luminous Intensity bin (e.g., HJ for 180-310mcd) to ensure uniform color and brightness across the panel.

This approach guarantees reliable, consistent, and long-lasting operation of all indicator LEDs.