LTLMH4TGX7DA LED Lamp Datasheet - Dimensions 4.2x4.2x6.2mm - Voltage 2.9V - Power 0.105W - Green 525nm - English Technical Document

1. Product Overview

This document details the specifications for a high-brightness surface mount LED lamp. The device is designed as a surface mount device (SMD) compatible with standard SMT assembly and industrial reflow soldering processes. It is offered in a package suitable for applications requiring a controlled radiation pattern without additional optics.

1.1 Core Advantages

• High Luminous Intensity: Delivers high brightness output for its package size.
• Energy Efficiency: Features low power consumption and high luminous efficacy.
• Robust Construction: Utilizes advanced epoxy technology providing superior moisture resistance and UV protection.
• Environmental Compliance: The product is lead-free, halogen-free, and compliant with RoHS directives.
• Narrow Viewing Angle: The package lens is designed to provide a controlled, narrow viewing angle (70/45° typical), making it suitable for directional lighting applications like signs without requiring secondary optics.

1.2 Target Market & Applications

This LED is primarily targeted at signage and display applications where reliability, brightness, and controlled light distribution are critical. Typical applications include:

• Video message signs and displays.
• Traffic information and guidance signs.
• General message and information boards.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed.

• Power Dissipation (Pd): 105 mW maximum. This is the total power the package can dissipate as heat.
• Forward Current: DC forward current is rated at 30 mA. A higher peak forward current of 100 mA is permissible under pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 10ms).
• Thermal Derating: The maximum DC forward current must be linearly derated by 0.5 mA/°C for ambient temperatures (TA) above 45°C.
• Temperature Range: Operating: -40°C to +85°C. Storage: -40°C to +100°C.
• Reflow Soldering: Withstands a maximum peak temperature of 260°C for 10 seconds, compatible with standard lead-free reflow profiles.

2.2 Electrical & Optical Characteristics

These parameters are measured at an ambient temperature (TA) of 25°C and define the device's performance under normal operating conditions.

• Luminous Intensity (Iv): Ranges from 5000 mcd (min) to 14500 mcd (max) at a test current (IF) of 20 mA, with a typical value of 9200 mcd. A ±15% testing tolerance is applied to bin limits.
• Forward Voltage (VF): Typically 2.9V, with a range from 2.5V to 3.5V at IF=20mA. This parameter is crucial for driver design and thermal management.
• Viewing Angle (2θ1/2): 70/45 degrees (typical). This asymmetric pattern indicates a narrower beam in one axis, ideal for certain sign applications.
• Dominant Wavelength (λd): 525 nm (typical), specifying the perceived green color of the LED. The range is 520 nm to 530 nm.
• Peak Emission Wavelength (λP): Typically 517 nm, representing the peak in the spectral power distribution.
• Spectral Half-Width (Δλ): Approximately 35 nm, indicating the spectral purity of the green light.
• Reverse Current (IR): Maximum 10 μA at a reverse voltage (VR) of 5V. The device is not designed for reverse bias operation; this test is for leakage characterization only.

2.3 Thermal Characteristics

Effective thermal management is essential for maintaining LED performance and longevity. Key considerations include:

• The power dissipation limit of 105 mW and the derating curve starting at 45°C highlight the need for adequate PCB thermal design.
• The recommended solder pad pattern includes a thermal pad (P3) intended to be connected to a heat sink or cooling mechanism to distribute operational heat.
• Avoiding rapid cooling after the reflow soldering peak temperature is advised to prevent thermal shock to the package.

3. Binning System Specification

To ensure color and brightness consistency in production applications, LEDs are sorted into bins.

3.1 Luminous Intensity Binning

LEDs are classified based on their measured luminous intensity at 20mA. The bin codes and ranges are:

• GV: 5000 – 6500 mcd
• GW: 6500 – 8500 mcd
• GX: 8500 – 11100 mcd
• GY: 11100 – 14500 mcd

Note: A tolerance of ±15% applies to each bin limit.

3.2 Dominant Wavelength Binning

LEDs are also sorted by their dominant wavelength to control color consistency:

• G1: 520 – 525 nm
• G2: 525 – 530 nm

Note: A tolerance of ±1 nm applies to each bin limit.

4. Performance Curve Analysis

While specific graphical curves are referenced in the document (e.g., Fig.1, Fig.6), typical characteristics for this class of device can be inferred from the tabular data:

• IV Curve Relationship: The forward voltage (VF) is directly related to the forward current (IF). Operating at the typical 20mA yields a VF of ~2.9V. Exceeding the maximum current will increase voltage drop and power dissipation.
• Temperature Dependence: Luminous intensity typically decreases as junction temperature increases. The derating requirement for forward current above 45°C is a direct indicator of this relationship, necessitating thermal management for consistent light output.
• Spectral Distribution: With a dominant wavelength of 525nm and a spectral half-width of ~35nm, the LED emits a relatively pure green light centered in the green spectrum.

5. Mechanical & Package Information

5.1 Outline Dimensions

The package has a rectangular footprint with a lens. Key dimensions (in mm) include:

• Body Size: 4.2 ±0.2 (L) x 4.2 ±0.2 (W).
• Total Height: 6.2 ±0.5.
• Lead spacing (where leads emerge from package): 2.0 ±0.5.
• A maximum resin protrusion of 1.0mm under the flange is permitted.
• General tolerance is ±0.25mm unless otherwise specified.

5.2 Polarity Identification & Pad Design

• Polarity: The device has three pads: P1 (Anode), P2 (Cathode), and P3 (Anode). P3 also serves as the primary thermal pad.
• Recommended Pad Pattern: The footprint includes a larger pad for P3 to facilitate heat transfer to the PCB. A fillet radius (R0.5) is suggested on the pad design. This LED is designed for reflow soldering and is not suitable for dip soldering.

6. Soldering & Assembly Guidelines

6.1 Storage & Moisture Sensitivity

The device is rated Moisture Sensitive Level 3 (MSL3) per JEDEC J-STD-020.

• Unopened bags can be stored at <30°C / 90% RH for up to 12 months.
• After opening, components must be soldered within 168 hours (7 days) when stored at <30°C / 60% RH.
• Baking at 60°C ±5°C for 20 hours is required if the humidity indicator card shows >10% RH, floor life exceeds 168 hours, or exposure to >30°C / 60% RH occurs. Baking should be performed only once.
• Unused LEDs should be stored with desiccant in a resealed moisture barrier bag.

6.2 Reflow Soldering Profile

A lead-free reflow profile is recommended:

• Preheat/Soak: 150°C to 200°C for a maximum of 120 seconds.
• Liquidous Time (tL): Time above 217°C should be 60-150 seconds.
• Peak Temperature (Tp): Maximum 260°C.
• Time within 5°C of Peak: Maximum 30 seconds.
• Total Ramp Time: Time from 25°C to peak should not exceed 5 minutes.

Critical Soldering Notes:

• Reflow soldering must not be performed more than twice.
• Hand soldering with an iron (max 315°C for 3 seconds) must not be done more than once.
• Avoid applying external stress to the LED during soldering while it is at high temperature.
• Avoid rapid cooling after the peak temperature.

6.3 Cleaning

If cleaning is necessary, use alcohol-based solvents such as isopropyl alcohol.

7. Packaging & Ordering Information

7.1 Packing Specification

The LEDs are supplied on embossed carrier tape wound onto reels.

• Carrier Tape Dimensions: Pocket pitch is 8.0 mm, tape width is 16.0 mm.
• Reel Specifications: Standard reel contains 1,000 pieces. Reel diameter is 330 mm ±2 mm.
• ESD Warning: The packaging is marked as containing Electrostatic Sensitive Devices (ESD), requiring safe handling procedures.

8. Application & Design Recommendations

8.1 Drive Circuit Design

LEDs are current-operated devices. For reliable operation and intensity uniformity, especially when connecting multiple LEDs in parallel, it is strongly recommended to use a current-limiting resistor in series with each LED. This compensates for the natural variation in forward voltage (VF) between individual devices, preventing current hogging and ensuring consistent brightness.

8.2 Thermal Management in Design

Given the power dissipation limit and thermal derating:

• Incorporate the recommended thermal pad (P3) into the PCB layout, connecting it to a copper pour or dedicated thermal via structure to dissipate heat.
• For high-density arrays or high ambient temperature applications, consider additional cooling mechanisms.
• Monitor the operating junction temperature to ensure it remains within safe limits for long-term reliability.

8.3 Optical Integration

The integrated lens provides a 70/45° viewing angle. Designers should verify this beam pattern meets the application's requirements for light distribution and viewing cone. For very narrow or specific patterns, secondary optics may still be required.

9. Technical Comparison & Differentiation

Compared to standard SMD or PLCC (Plastic Leaded Chip Carrier) packages, this surface mount lamp offers distinct advantages:

• Integrated Optical Control: The package includes a lens designed for a specific, controlled radiation pattern (narrow viewing angle), reducing or eliminating the need for additional external optics in many sign applications, which simplifies assembly and lowers cost.
• High Brightness in SMD Format: It delivers luminous intensity levels associated with larger or discrete LEDs in a compact, automated SMT-compatible package.
• Robustness: The use of advanced epoxy materials enhances moisture and UV resistance compared to some standard SMD packages, improving suitability for outdoor or harsh environment applications.

10. Frequently Asked Questions (Based on Technical Parameters)

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

Peak Wavelength (λP ~517nm) is the single wavelength at which the emission spectrum is strongest. Dominant Wavelength (λd ~525nm) is a calculated value derived from the color coordinates on the CIE chromaticity diagram; it represents the single wavelength that best describes the perceived color of the light to the human eye. For green LEDs, λd is often longer than λP.

10.2 Can I drive this LED at 30mA continuously?

While the Absolute Maximum Rating for DC forward current is 30mA, continuous operation at this limit requires excellent thermal management to keep the junction temperature within safe limits, as power dissipation will be near the 105mW maximum. For reliable long-term operation, driving at or below the test condition of 20mA is advisable unless the thermal design has been thoroughly validated.

10.3 Why is a current-limiting resistor needed for each LED in parallel?

The forward voltage (VF) has a range (2.5V to 3.5V). If multiple LEDs are connected directly in parallel to a voltage source, the LED with the lowest VF will draw disproportionately more current, potentially exceeding its ratings and failing, causing a chain reaction. A series resistor for each LED helps balance the current by adding a linear impedance, ensuring more uniform current sharing and brightness.

11. Practical Design & Usage Case Study

Scenario: Designing a compact traffic information sign.

1. Component Selection: This LED is chosen for its high brightness (to ensure visibility in daylight), green color (for \"proceed\" or information messages), and narrow viewing angle (to concentrate light toward drivers). The GY bin might be selected for maximum brightness.
2. Circuit Design: A constant current driver circuit is designed. Each LED in a string has a series resistor calculated based on the supply voltage and the typical VF (2.9V) at the desired operating current (e.g., 18mA for a margin below the 20mA test condition).
3. PCB Layout: The PCB footprint follows the recommended pad pattern. The thermal pad (P3) is connected to a large copper area on the board with thermal vias to an internal ground plane to act as a heat spreader.
4. Assembly: The MSL3 rating is noted. Boards are assembled using a controlled reflow process adhering to the 260°C peak profile. Opened reels are used within the 168-hour floor life.
5. Result: The sign achieves bright, uniform illumination with consistent color across all message elements, reliable operation over a wide temperature range, and long service life due to proper thermal and electrical design.

12. Operating Principle

This device is a light-emitting diode (LED). It operates on the principle of electroluminescence in a semiconductor material. When a forward voltage is applied across the P-N junction, electrons and holes recombine in the active region (composed of InGaN for green light). This recombination process releases energy in the form of photons (light). The specific composition of the semiconductor layers determines the wavelength (color) of the emitted light. The integrated epoxy lens then shapes and directs this emitted light into the desired beam pattern.

13. Technology Trends

The surface mount lamp format represents an ongoing trend in LED packaging:

• Increased Integration: Moving beyond simple emitters to packages that integrate optical control (lenses), as seen here, reducing system complexity.
• Higher Efficiency & Luminance: Continuous improvements in semiconductor epitaxy and phosphor technology (for white LEDs) drive higher lumens per watt and higher luminance (brightness per unit area) from smaller packages.
• Enhanced Reliability: Development of more robust encapsulant materials (like the advanced epoxy mentioned) improves resistance to thermal cycling, moisture, and UV radiation, expanding application environments.
• Standardization for Automation: The SMT format is dominant, favoring high-speed, automated pick-and-place assembly, which lowers manufacturing costs and improves consistency.