3.1mm Through Hole LED LTL1CHKGTLC Datasheet - Green Color - 2.4V Forward Voltage - 75mW Power Dissipation - English Technical Document

1. Product Overview

This document details the specifications for a high-efficiency, green through-hole LED. The device is designed for general-purpose indicator applications where reliable performance, low power consumption, and high luminous intensity are required. Its primary target markets include consumer electronics, industrial control panels, communication equipment, and various household appliances requiring status indication.

The core advantages of this LED component include its compliance with lead-free and RoHS environmental standards, offering a high luminous intensity output from a compact 3.1mm diameter package. It features low power consumption and is compatible with integrated circuits due to its low current requirement, making it suitable for modern electronic designs.

2. Technical Parameters Deep Objective Interpretation

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation at or beyond these limits is not advised.

• Power Dissipation (Pd): 75 mW. This is the maximum amount of power the LED can dissipate as heat at an ambient temperature (T_A) of 25°C.
• DC Forward Current (I_F): 30 mA. The maximum continuous current that can be passed through the LED.
• Peak Forward Current: 60 mA. This is permissible only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width) to briefly achieve higher light output without overheating.
• Reverse Voltage (V_R): 5 V. Exceeding this voltage in reverse bias can cause immediate junction breakdown.
• Operating Temperature Range: -40°C to +100°C. The ambient temperature range within which the LED is designed to function.
• Lead Soldering Temperature: 260°C for 5 seconds, measured 2.0mm from the LED body. This defines the thermal profile for hand or wave soldering.

2.2 Electrical / Optical Characteristics

These are the typical performance parameters measured at T_A=25°C, defining the device's normal operating behavior.

• Luminous Intensity (I_V): 18 to 52 mcd (minimum to maximum) at a test current (I_F) of 2mA. This wide range is managed through a binning system (see Section 3). The intensity is measured using a sensor filtered to match the human eye's photopic response (CIE curve).
• Forward Voltage (V_F): 2.1V to 2.4V (typical) at I_F = 2mA. This parameter is crucial for designing the current-limiting resistor in the drive circuit.
• Viewing Angle (2θ_1/2): 45 degrees. This is the full angle at which the luminous intensity drops to half of its value measured on-axis. A 45° angle provides a reasonably wide viewing cone.
• Peak Emission Wavelength (λ_P): 575 nm. The wavelength at which the spectral power output is highest.
• Dominant Wavelength (λ_d): 572 nm. This is derived from the CIE chromaticity diagram and represents the perceived color of the light, which is a pure green.
• Spectral Line Half-Width (Δλ): 11 nm. This indicates the spectral purity; a narrower width means a more saturated, pure color.
• Reverse Current (I_R): 100 µA maximum at V_R = 5V.
• Capacitance (C): 40 pF typical at zero bias and 1MHz frequency, relevant for high-frequency switching applications.

3. Binning System Explanation

To ensure consistency in brightness and color for end-users, LEDs are sorted into bins based on measured performance.

3.1 Luminous Intensity Binning

Units are in millicandelas (mcd) measured at 2 mA. The tolerance for each bin limit is ±15%.

• Bin 3Y: 18 mcd (Min) to 23 mcd (Max)
• Bin 3Z: 23 mcd to 30 mcd
• Bin A: 30 mcd to 38 mcd
• Bin B: 38 mcd to 52 mcd

The bin code is marked on the packing bag, allowing designers to select LEDs with a specific brightness range for their application.

3.2 Dominant Wavelength Binning

Units are in nanometers (nm) measured at 2 mA. The tolerance for each bin limit is ±1 nm. This ensures a very tight control over the perceived green color.

• 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

The datasheet references typical characteristic curves which are essential for understanding device behavior under non-standard conditions. While the specific graphs are not reproduced in text, their implications are analyzed below.

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

The I-V characteristic is non-linear. For an AlInGaP LED like this one, the forward voltage exhibits a negative temperature coefficient. This means as the junction temperature increases, the forward voltage required to achieve the same current decreases slightly. This characteristic is important for constant-current drive design to ensure stable light output.

4.2 Luminous Intensity vs. Forward Current

The light output (luminous intensity) is approximately proportional to the forward current in the typical operating range. However, efficiency may drop at very high currents due to increased heat generation (droop effect). Operating at or below the recommended DC current ensures optimal efficiency and longevity.

4.3 Luminous Intensity vs. Ambient Temperature

The light output of LEDs decreases as the junction temperature rises. For AlInGaP materials, this thermal quenching effect is significant. Designers must consider thermal management, especially in high-ambient-temperature environments or when driving the LED at high currents, to maintain consistent brightness.

4.4 Spectral Distribution

The referenced spectral graph would show a peak at approximately 575 nm with a typical half-width of 11 nm. The dominant wavelength of 572 nm defines the perceived green color point on the CIE chart.

5. Mechanical and Packaging Information

5.1 Package Dimensions

The device is housed in a standard 3.1mm diameter round through-hole package. Key dimensional notes include:

• All dimensions are in millimeters (inches provided in parentheses).
• Standard tolerance is ±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 emerge from the package body, which is critical for PCB layout.

5.2 Polarity Identification

For through-hole LEDs, the cathode is typically identified by a flat edge on the lens rim or by the shorter lead. The datasheet implies standard industry practice; the longer lead is the anode (+), and the shorter lead is the cathode (-). Correct polarity must be observed during assembly.

6. Soldering and Assembly Guidelines

Proper handling is critical to prevent damage and ensure reliability.

6.1 Storage Conditions

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 outside the original packaging, use a sealed container with desiccant or a nitrogen ambient.

6.2 Lead Forming

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

6.3 Soldering Process

• Maintain a minimum clearance of 2mm from the base of the lens to the solder point. Never immerse the lens in solder.
• Avoid applying external stress to the leads while the LED is hot from soldering.
• Recommended Soldering Conditions:
  • Hand Soldering (Iron): Maximum temperature 300°C, maximum time 3 seconds per lead (one time only).
  • Wave Soldering: Maximum preheat temperature 100°C for up to 60 seconds. Solder wave temperature maximum 260°C for a maximum of 5 seconds.
• Excessive temperature or time can deform the lens or cause catastrophic failure.

6.4 Cleaning

If cleaning is necessary, use only alcohol-based solvents such as isopropyl alcohol. Harsh chemicals may damage the lens material.

7. Packaging and Ordering Information

7.1 Packing Specifications

The standard packaging flow is as follows:

• LEDs are packed in bags containing 1000, 500, or 250 pieces.
• Ten (10) packing bags are placed into an inner carton (total 10,000 pieces).
• Eight (8) inner cartons are packed into an outer shipping carton (total 80,000 pieces).
• Within a shipping lot, only the final pack may contain a non-full quantity.

8. Application Recommendations

8.1 Typical Application Scenarios

This LED is suitable for a wide range of indicator applications, including but not limited to:

• Power status indicators on consumer electronics (TVs, audio equipment, chargers).
• Signal and status lights on network routers, modems, and communication devices.
• Panel indicators on industrial control systems, test equipment, and instrumentation.
• Backlighting for switches, buttons, and legends in household appliances.

Important Note: The datasheet explicitly states this LED is for ordinary electronic equipment. Applications requiring exceptional reliability, especially where failure could jeopardize life or health (aviation, medical, transportation safety), require prior consultation with the manufacturer.

8.2 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness when using multiple LEDs, a series current-limiting resistor for each LED is strongly recommended (Circuit Model A).

• Circuit Model A (Recommended): Each LED has its own series resistor connected to the voltage supply. This compensates for the natural variation in forward voltage (V_F) from one LED to another, ensuring each receives the same current and thus has similar brightness.
• Circuit Model B (Not Recommended): Multiple LEDs connected in parallel with a single shared resistor. Due to V_F variance, current will not divide equally, leading to noticeable differences in brightness between LEDs.

The resistor value (R) is calculated using Ohm's Law: R = (V_supply - V_F) / I_F. Use the maximum V_F from the datasheet (2.4V) for a conservative design that guarantees the current does not exceed the desired I_F.

8.3 Electrostatic Discharge (ESD) Protection

LEDs are sensitive to electrostatic discharge. ESD damage can manifest as high reverse leakage current, low forward voltage, or failure to illuminate at low currents.

Prevention Measures:

• Operators should wear conductive wrist straps or anti-static gloves.
• All equipment, workstations, and storage racks must be properly grounded.
• Use an ionizer to neutralize static charge that may accumulate on the plastic lens.

ESD Verification Test: To check a suspect LED, measure its forward voltage at a very low current (e.g., 0.1mA). A \"good\" AlInGaP LED should have a V_F greater than 1.4V at this test condition.

9. Technical Comparison and Differentiation

This AlInGaP-based green LED offers specific advantages:

• vs. Traditional GaP Green LEDs: AlInGaP technology provides significantly higher luminous efficiency and a more saturated, pure green color (dominant wavelength ~572nm) compared to the yellowish-green of older GaP LEDs.
• vs. InGaN Green LEDs: While InGaN LEDs can achieve very high brightness, AlInGaP LEDs often have superior performance in the amber to red spectrum and specific green wavelengths, with potentially lower forward voltage and excellent stability.
• Key Differentiators: The combination of a 3.1mm package, a well-defined 45° viewing angle, a comprehensive binning system for both intensity and wavelength, and clear application cautions makes this a reliable and predictable choice for standard indicator use.

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 Can I drive this LED directly from a 5V supply without a resistor?

No, this will destroy the LED. An LED has very low dynamic resistance when forward biased. Connecting it directly to a voltage source like 5V will cause excessive current to flow, far exceeding the absolute maximum rating of 30mA DC, leading to immediate overheating and failure. A series current-limiting resistor is always required when using a voltage source.

10.2 Why is there such a wide range in luminous intensity (18-52 mcd)?

This range represents the total spread across the entire production distribution. Individual LEDs are sorted into specific \"bins\" (3Y, 3Z, A, B) with much tighter ranges. By specifying a required bin code when ordering, designers can ensure consistency in brightness across all units in their production run.

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

Peak Wavelength (λ_P): The physical wavelength at which the LED emits the most optical power. It's the highest point on the spectral output graph.
Dominant Wavelength (λ_d): A calculated value based on human color perception (CIE chart). It is the wavelength of a pure monochromatic light that would appear to have the same color as the LED's output. λ_d is more relevant for describing the perceived color, which is why it is used for binning.

10.4 How do I choose the right current for my application?

The test condition is 2mA, which is a common low-current rating for indicator LEDs. For standard indicator brightness, operating between 2mA and 10mA is typical. For higher brightness, you can approach the maximum DC rating of 20mA, but you must consider the increased power dissipation (P_d = V_F * I_F) to ensure it stays below 75mW, especially at higher ambient temperatures. Always refer to the derating curve (linear from 50°C at 0.4mA/°C).

11. Practical Design and Usage Case

Scenario: Designing a power \"ON\" indicator for a device powered by a 12V DC wall adapter. A single green LED is required.

1. Parameter Selection: Target a clearly visible but not glaring indicator. Choose an operating current (I_F) of 5mA.
2. Resistor Calculation: Use the maximum V_F of 2.4V for a safe design.
   R = (V_supply - V_F) / I_F = (12V - 2.4V) / 0.005A = 9.6V / 0.005A = 1920 Ω.
   The nearest standard E24 resistor value is 1.8kΩ or 2.2kΩ. Choosing 2.2kΩ will yield a slightly lower current (~4.36mA), which is acceptable and increases longevity.
3. Power Dissipation Check: P_resistor = I_F² * R = (0.00436)² * 2200 ≈ 0.042W. A standard 1/8W (0.125W) or 1/4W resistor is more than sufficient.
   P_LED = V_F * I_F ≈ 2.4V * 0.00436A ≈ 0.0105W (10.5mW), well below the 75mW maximum.
4. PCB Layout: Place the resistor in series with the anode of the LED. Ensure the hole spacing matches the LED's lead spacing where they emerge from the body. Provide a keep-out area of at least 2mm around the LED base for soldering clearance.

12. Principle Introduction

This LED is based on Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor material. When a forward voltage is applied, electrons from the n-type region and holes from the p-type region are injected into the active region. When these charge carriers recombine, they release energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy of the semiconductor, which directly dictates the wavelength (color) of the emitted light. In this case, the alloy is engineered to produce photons in the green spectrum with a dominant wavelength of approximately 572 nanometers. The transparent epoxy lens serves to protect the semiconductor chip, shape the light output beam (resulting in the 45° viewing angle), and enhance light extraction from the package.

13. Development Trends

While through-hole LEDs remain vital for prototyping, repair, and certain applications, the overall industry trend is strongly towards surface-mount device (SMD) packages like 0603, 0805, and 0402 for mainstream production. SMD LEDs offer advantages in automated assembly, board space savings, and lower profile. For through-hole components, the focus continues to be on improving efficiency (more light output per mA), enhancing reliability under harsh conditions, and providing more precise and consistent binning. The underlying AlInGaP material technology is mature but continues to see incremental improvements in internal quantum efficiency and thermal performance. The principles of proper drive, thermal management, and ESD protection outlined in this datasheet remain universally critical for LED application design, regardless of package type.