LTL17KGL6D Green LED Lamp Datasheet - T-1 (3mm) Diameter - 2.5V Forward Voltage - 75mW Power Dissipation - English Technical Document

1. Product Overview

The LTL17KGL6D is a high-efficiency, low-power consumption through-hole LED lamp designed for status indication and signaling applications. It features a popular T-1 (3mm) diameter package with a green diffused lens, offering a balanced combination of brightness and wide viewing angle suitable for various electronic devices.

1.1 Core Advantages

• High Luminous Efficiency: Delivers high luminous intensity output relative to its low power consumption, making it energy-efficient.
• Design Flexibility: Available in standard through-hole packages suitable for manual or automated PCB assembly processes.
• Environmental Compliance: This is a lead (Pb)-free product, compliant with RoHS directives.
• Reliable Performance: Designed for stable operation across a standard industrial temperature range.

1.2 Target Applications

This LED is versatile and finds use in numerous sectors requiring clear visual indicators. Primary application areas include:

• Communication Equipment: Status lights on routers, modems, and network switches.
• Computer Peripherals: Power and activity indicators on desktops, laptops, and external drives.
• Consumer Electronics: Indicator lights on audio/video equipment, home appliances, and toys.
• Industrial Controls: Panel indicators on machinery, control systems, and instrumentation.
• Home Appliances: Power-on, mode, or timer indicators on various household devices.

2. In-Depth Technical Parameter Analysis

A detailed examination of the electrical and optical specifications is crucial for proper circuit design and performance expectation.

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation should always be maintained within these boundaries.

• Power Dissipation (P_D): 75 mW maximum. Exceeding this can lead to overheating and reduced lifespan.
• Forward Current: Continuous DC forward current is rated at 30 mA. A peak forward current of 90 mA is permissible only under strict conditions (duty cycle ≤ 1/10, pulse width ≤ 10μs) for brief surges.
• Temperature Ranges: The device can operate from -40°C to +85°C and be stored from -40°C to +100°C.
• Soldering Temperature: Leads can withstand 260°C for a maximum of 5 seconds when measured 2.0mm from the LED body, which is critical for assembly processes.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters measured at 25°C ambient temperature with a forward current (I_F) of 20mA, which is the standard test condition.

• Luminous Intensity (I_V): Ranges from a minimum of 180 mcd to a typical 310 mcd, with a maximum up to 880 mcd depending on the specific bin. This intensity is measured using a sensor filtered to match the human eye's photopic response (CIE curve).
• Viewing Angle (2θ_1/2): 60 degrees. This is the full angle at which the luminous intensity drops to half of its peak axial value, indicating a moderately wide viewing cone suitable for panel indicators.
• Wavelength: The peak emission wavelength (λ_P) is typically 574 nm. The dominant wavelength (λ_d), which defines the perceived color, ranges from 566 nm to 578 nm, corresponding to a green color. The spectral half-width (Δλ) is approximately 11 nm, indicating a relatively pure color emission.
• Forward Voltage (V_F): Typically 2.5V, with a maximum of 2.1V at 20mA. This parameter is essential for calculating the current-limiting resistor value in series with the LED.
• Reverse Current (I_R): Maximum 100 μA at a reverse voltage (V_R) of 5V. It is critical to note that this LED 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. The LTL17KGL6D uses a two-dimensional binning system.

3.1 Luminous Intensity Binning

LEDs are classified into three primary bins based on their measured luminous intensity at 20mA. Each bin has a ±15% tolerance on its limits.

• Bin HJ: 180 mcd (Min) to 310 mcd (Max)
• Bin KL: 310 mcd (Min) to 520 mcd (Max)
• Bin MN: 520 mcd (Min) to 880 mcd (Max)

3.2 Dominant Wavelength Binning

For color consistency, LEDs are binned into narrow wavelength ranges. Each bin has a tolerance of ±1 nm.

• 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

This binning allows designers to select parts that meet specific brightness and color point requirements for their application, ensuring visual uniformity when multiple LEDs are used.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet, their implications are standard for LED behavior.

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

The relationship is non-linear and exponential. The typical V_F of 2.5V at 20mA is a key design point. Operating significantly above 20mA will cause V_F to increase slightly but will primarily increase light output and power dissipation, which must be managed to stay within maximum ratings.

4.2 Luminous Intensity vs. Forward Current

Luminous intensity is approximately proportional to forward current in the normal operating range. Driving the LED at less than 20mA will reduce brightness, while driving it higher (up to the 30mA DC maximum) will increase brightness but also heat generation.

4.3 Spectral Distribution

The referenced curve would show a single peak around 574 nm with a typical half-width of 11 nm, confirming its monochromatic green light emission without significant sidebands.

5. Mechanical & Package Information

5.1 Outline Dimensions

The LED conforms to the standard T-1 (3mm) radial leaded package. Key dimensional notes include:

• All dimensions are in millimeters, with a general tolerance of ±0.25mm unless specified otherwise.
• The maximum protrusion of resin under the flange is 1.0mm.
• Lead spacing is measured at the point where leads exit the package body, which is critical for PCB hole spacing.

5.2 Polarity Identification

For radial LEDs, the longer lead is typically the anode (positive), and the shorter lead is the cathode (negative). The flat side on the flange of the LED body may also indicate the cathode side. Correct polarity is essential for operation.

6. Soldering & Assembly Guidelines

Proper handling is required to maintain reliability and prevent damage.

6.1 Storage Conditions

For long-term storage outside the original moisture-barrier bag, the ambient should not exceed 30°C or 70% relative humidity. If removed from original packaging, use within three months is recommended. For extended storage, use a sealed container with desiccant or a nitrogen atmosphere.

6.2 Lead Forming

If leads need to be bent, this must be done before soldering and at normal room temperature. The bend should be made at least 3mm away from the base of the LED lens. The base of the LED should not be used as a fulcrum during bending to avoid stress on the internal die attach.

6.3 Soldering Process

Critical Rule: Maintain a minimum distance of 2mm from the base of the epoxy lens to the solder point. Do not immerse the lens in solder.

• Hand Soldering (Iron): Maximum temperature 350°C for a maximum of 3 seconds per lead. Apply heat to the lead, not the body.
• Wave Soldering: Pre-heat to a maximum of 100°C for up to 60 seconds. Solder wave temperature should be a maximum of 260°C with a contact time of 5 seconds maximum. The LED should be positioned so the solder wave does not come within 2mm of the lens base.
• Not Recommended: Infrared (IR) reflow soldering is explicitly stated as unsuitable for this through-hole LED product.

Excessive temperature or time can cause lens deformation, internal wire bond failure, or degradation of the epoxy material.

6.4 Cleaning

If cleaning is necessary after soldering, use alcohol-based solvents like isopropyl alcohol. Avoid harsh or abrasive chemicals.

7. Packaging & Ordering Information

7.1 Packaging Specification

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

• 1000, 500, 200, or 100 pieces per packing bag.
• 10 packing bags are placed in an inner carton (e.g., 10,000 pcs for 1000/bag configuration).
• 8 inner cartons are packed into an outer shipping carton (e.g., 80,000 pcs total).

8. Application Design Recommendations

8.1 Drive Circuit Design

LEDs are current-driven devices. To ensure stable and uniform brightness, especially when using multiple LEDs, a series current-limiting resistor is mandatory for each LED or each parallel string.

• Recommended Circuit (Circuit A): Each LED has its own series resistor connected to the voltage supply. This compensates for minor variations in the forward voltage (V_F) between individual LEDs, ensuring they all draw approximately the same current and have uniform brightness.
• Not Recommended (Circuit B): Connecting multiple LEDs directly in parallel with a single shared resistor is discouraged. Small differences in the I-V characteristics of each LED can cause significant current imbalance, where one LED may draw much more current than others, leading to uneven brightness and potential overstress of the brightest LED.

The resistor value (R) is calculated using Ohm's Law: R = (V_supply - V_F) / I_F. For a 5V supply, a typical V_F of 2.5V, and a desired I_F of 20mA (0.02A), R = (5 - 2.5) / 0.02 = 125 Ω. A standard 120 Ω or 150 Ω resistor would be suitable, also affecting the actual current and brightness slightly.

8.2 Electrostatic Discharge (ESD) Protection

LEDs are sensitive to electrostatic discharge. Precautions must be taken during handling and assembly:

• Operators should wear grounded wrist straps or anti-static gloves.
• All workstations, tools, and equipment must be properly grounded.
• Use ionizers to neutralize static charge that can build up on the plastic lens.
• Implement an ESD control program with training and regular checks of work areas.

9. Technical Comparison & Design Considerations

9.1 Comparison with Other Indicator LEDs

The LTL17KGL6D, with its T-1 package and green color, sits in a very common category. Its differentiation lies in its specific binning options for intensity and wavelength, allowing for tighter consistency in applications where multiple indicators are used. Compared to smaller SMD LEDs, through-hole LEDs like this one are often easier for prototyping, manual assembly, and applications where the indicator is mounted on a front panel separate from the main PCB.

9.2 Thermal Management Considerations

While the power dissipation is low (75mW max), continuous operation at maximum current (30mA) in high ambient temperatures (up to 85°C) requires consideration. The LED's lifetime and light output can degrade with excessive junction temperature. Ensuring adequate spacing on the PCB and avoiding enclosing the LED in a tightly sealed, unventilated space can help maintain optimal operating temperature.

10. Frequently Asked Questions (FAQs)

10.1 Can I drive this LED without a resistor?

No. An LED must be driven with a current-limiting device, almost always a resistor in simple DC circuits. Connecting it directly to a voltage source like a battery or power supply will cause it to draw excessive current, leading to immediate or rapid failure.

10.2 What is the difference between luminous intensity (mcd) and viewing angle?

Luminous intensity (measured in millicandelas, mcd) is the brightness measured along the central axis of the LED. The viewing angle (e.g., 60°) describes how this light is distributed. A high mcd value with a narrow viewing angle produces a very bright but focused beam. This LED's 60° angle provides a good balance, offering noticeable brightness over a wide area, ideal for panel indicators.

10.3 How do I select the correct bin?

Select the intensity bin (HJ, KL, MN) based on how bright you need the indicator to be. Select the wavelength bin (H06-H11) based on the specific shade of green required for your application, often for color matching or branding purposes. For most general applications, specifying a range (e.g., KL bin for intensity) is sufficient.

10.4 Is this LED suitable for outdoor use?

The datasheet states it is good for indoor and outdoor signs. However, for harsh outdoor environments with direct UV exposure, moisture, and wide temperature swings, the epoxy lens may degrade over time. For critical outdoor applications, consulting the manufacturer for specific reliability data or considering LEDs with more robust packaging is advised.

11. Practical Application Example

11.1 Designing a Multi-LED Status Panel

Scenario: A control panel requires four green power status indicators, all appearing equally bright and the same color.

Design Steps:

1. Circuit Design: Use the recommended Circuit A. For a 12V system rail, calculate the series resistor for each LED. R = (12V - 2.5V) / 0.02A = 475 Ω. A standard 470 Ω resistor will provide approximately 20.2mA, which is safe and within specification.
2. Component Selection: Order all four LEDs from the same luminous intensity bin (e.g., KL bin: 310-520 mcd) and the same dominant wavelength bin (e.g., H08 bin: 570-572 nm) to ensure visual consistency.
3. PCB Layout: Place the LEDs with the recommended 2mm clearance from the lens base to any solder pad or trace. Ensure hole spacing matches the LED's lead spacing at the package exit point.
4. Assembly: Follow the soldering guidelines. Use wave soldering if the PCB is assembled en masse, ensuring the fixture holds the LEDs so the wave does not touch the lens base.
5. ESD Precautions: Handle the LEDs at an ESD-safe workstation during manual insertion or inspection.

This approach guarantees reliable operation and a professional, uniform appearance for the end product.