Surface Mount LED Lamp LTLMH4ERADA Specification - Dimensions 4.2x4.2x6.2mm - Voltage 1.8-2.4V - Red 626nm - English Technical Document

1. Product Overview

This document details the specifications for a high-brightness surface mount LED lamp. Designed for compatibility with standard SMT assembly processes, this device offers a robust solution for applications requiring precise light output and reliable performance. The LED features a specialized package designed to deliver a controlled radiation pattern suitable for signage without the need for additional secondary optics.

1.1 Core Advantages and Target Market

The primary advantages of this LED include its high luminous intensity output combined with low power consumption, resulting in high efficiency. The package is constructed using advanced epoxy technology, providing superior moisture resistance and UV protection, enhancing its durability for demanding environments. It is compliant with lead-free, halogen-free, and RoHS standards. The device is specifically targeted at applications such as video message signs, traffic signs, and other informational display boards where visibility and reliability are critical.

2. In-Depth Technical Parameter Analysis

A comprehensive analysis of the device's operational limits and performance characteristics under standard conditions (TA=25°C).

2.1 Absolute Maximum Ratings

• Power Dissipation: 120 mW maximum.
• Forward Current: 50 mA DC maximum. A peak forward current of 120 mA is permissible under pulsed conditions (duty cycle ≤1/10, pulse width ≤10ms).
• Thermal Derating: The DC forward current must be linearly derated by 0.75 mA/°C for ambient temperatures above 45°C.
• Temperature Range: Operational from -40°C to +85°C; storage from -40°C to +100°C.
• Reflow Soldering: Withstands a maximum profile of 260°C peak temperature for 10 seconds.

2.2 Electrical and Optical Characteristics

Key performance parameters measured at a standard test current of IF=20mA.

• Luminous Intensity (Iv): Ranges from a minimum of 1500 mcd to a maximum of 4200 mcd, with a typical value subject to binning. Measurement follows the CIE eye-response curve.
• Viewing Angle (2θ1/2): The typical viewing angle is specified as 100/40°, indicating an oval radiation pattern. Measurement tolerance is ±2 degrees.
• Wavelength: Peak emission wavelength (λP) is typically 634 nm. The dominant wavelength (λd) ranges from 618 nm to 630 nm, defining the perceived red color, centered around 626nm.
• Spectral Line Half-Width (Δλ): Typically 15 nm.
• Forward Voltage (VF): Ranges from 1.8 V to 2.4 V at 20mA.
• Reverse Current (IR): Maximum of 10 μA at a reverse voltage (VR) of 5V. The device is not designed for reverse bias operation.

3. Binning System Specification

To ensure consistency in applications, the LEDs are sorted into bins based on key parameters.

3.1 Luminous Intensity Binning

LEDs are classified into four bins (R, S, T, U) based on their minimum and maximum luminous intensity at IF=20mA. The bin limits have a ±15% testing tolerance.

• Bin R: 1500 - 1900 mcd
• Bin S: 1900 - 2500 mcd
• Bin T: 2500 - 3200 mcd
• Bin U: 3200 - 4200 mcd

The specific bin code is marked on each packing bag for traceability.

3.2 Forward Voltage Binning

LEDs are also binned by forward voltage into three categories (1A, 2A, 3A) at IF=20mA, with a ±0.1V tolerance on each limit.

• Bin 1A: 1.8 - 2.0 V
• Bin 2A: 2.0 - 2.2 V
• Bin 3A: 2.2 - 2.4 V

4. Performance Curve Analysis

Typical performance curves illustrate the relationship between key parameters. These curves are essential for design engineers to predict behavior under non-standard conditions.

4.1 Luminous Intensity vs. Forward Current

The curve shows the non-linear relationship between forward current (IF) and luminous intensity (Iv). Intensity increases with current but designers must remain within the absolute maximum current ratings to ensure longevity.

4.2 Forward Voltage vs. Forward Current

This characteristic curve demonstrates the diode's exponential V-I relationship. Understanding this is crucial for designing appropriate current-limiting circuitry.

4.3 Spectral Distribution

The spectral power distribution curve centers around the peak wavelength of 634 nm with a typical half-width of 15 nm, confirming the narrow-band red emission.

5. Mechanical and Package Information

5.1 Outline Dimensions

The device has a compact surface-mount footprint. Key dimensions include a body size of 4.2mm ±0.2mm in length and width, and a total height of 6.2mm ±0.5mm including the lens. The leads have a spacing of 2.0mm ±0.5mm where they emerge from the package. All dimensions are in millimeters, with a general tolerance of ±0.25mm unless otherwise specified.

5.2 Polarity Identification and Pad Design

The device has three pins: P1 (Anode), P2 (Cathode), and P3 (Anode). Pin P3 is recommended to be connected to a heat sink or cooling mechanism on the PCB to aid in thermal management during operation. A recommended solder pad pattern is provided to ensure proper soldering and thermal performance.

6. Soldering and Assembly Guidelines

6.1 Storage and Moisture Sensitivity

This component is classified as Moisture Sensitivity Level 3 (MSL3) per JEDEC J-STD-020. LEDs in an unopened moisture barrier bag can be stored for up to 12 months at <30°C and 90% RH. After opening, the devices must be kept at <30°C and 60% RH and must be soldered within 168 hours (7 days). Baking at 60°C ±5°C for 20 hours is required if the humidity indicator card shows >10% RH, the floor life exceeds 168 hours, or if exposed to >30°C/60% RH. Baking should be performed only once.

6.2 Reflow Soldering Profile

A lead-free reflow soldering 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 above Classification Temperature (Tc=255°C): Maximum 30 seconds.
• Total Time from 25°C to Peak: Maximum 5 minutes.

Reflow soldering must not be performed more than twice. The device is designed for reflow soldering and is not suitable for dip soldering.

6.3 Cleaning and Handling

If cleaning is necessary, use alcohol-based solvents like isopropyl alcohol. Avoid applying mechanical stress to the LED during soldering while it is at high temperature, and avoid rapid cooling from peak temperature.

7. Packaging and Ordering Information

7.1 Packing Specification

The LEDs are supplied on embossed carrier tape within a reel. The reel contains a total of 1,000 pieces. Detailed carrier tape dimensions are provided, including pocket size, pitch, and reel dimensions (e.g., 330mm reel diameter). The packaging is marked with an \"Electrostatic Sensitive Devices\" warning.

8. Application Recommendations

8.1 Typical Application Scenarios

This LED is well-suited for both indoor and outdoor signage applications, including video message signs, traffic signs, and general message displays. Its high brightness and controlled viewing angle make it ideal for applications requiring good visibility.

8.2 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness when connecting multiple LEDs in parallel, it is strongly recommended to use a current-limiting resistor in series with each individual LED. Driving LEDs in parallel without individual resistors can lead to current hogging and uneven brightness due to minor variations in forward voltage (Vf) between devices.

8.3 Thermal Management Considerations

While the device has a specified power dissipation, effective thermal management via the PCB is crucial for maintaining performance and longevity, especially at higher ambient temperatures or drive currents. Utilizing the recommended pad for pin P3 to connect to a thermal plane or heat sink is a key design practice.

9. Technical Comparison and Differentiation

Compared to standard SMD or PLCC (Plastic Leaded Chip Carrier) packages, this surface mount lamp offers a significant advantage in optical control. Its integrated lens package provides a smooth radiation pattern and narrow viewing angle control without requiring an additional external optical lens. This simplifies the end-product design, reduces part count, and can lower overall assembly costs while providing targeted illumination.

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 What is the difference between peak wavelength and dominant wavelength?

Peak wavelength (λP) is the wavelength at which the emitted optical power is maximum (typically 634nm here). Dominant wavelength (λd) is derived from the CIE chromaticity diagram and represents the single wavelength that defines the perceived color of the light (618-630nm here, centered on 626nm). Dominant wavelength is more relevant for color specification.

10.2 Can I drive this LED without a current-limiting resistor?

No. Operating an LED directly from a voltage source is not recommended and will likely destroy the device due to excessive current. A series resistor or constant current driver is mandatory for reliable operation.

10.3 Why is there a ±15% tolerance on the luminous intensity bin limits?

This tolerance accounts for measurement variability in the production test environment. It ensures that all devices labeled within a specific bin will perform within the declared intensity range when measured under the defined standard conditions.

11. Practical Design and Usage Case

Scenario: Designing a High-Visibility Exit Sign. An engineer selects this LED for a new exit sign design requiring high brightness and long life. They choose LEDs from bin \"T\" for consistent high output. In the circuit design, they use a constant current driver set to 20mA per LED string. They place multiple LEDs in series within each string to meet voltage requirements, avoiding parallel connections without individual resistors. On the PCB layout, they follow the recommended pad pattern, connecting the P3 pad of each LED to a large copper pour for heat dissipation. They specify a PCBA assembly house that follows the provided reflow profile and ensure the components are used within the 168-hour floor life after the moisture barrier bag is opened.

12. Operating Principle Introduction

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 recombine with holes, releasing energy in the form of photons (light). The specific semiconductor material used (AllnGaP - Aluminum Indium Gallium Phosphide) determines the color of the emitted light, in this case, red with a dominant wavelength around 626nm. The epoxy package encapsulates the semiconductor die, provides mechanical protection, and incorporates a lens to shape the light output.

13. Technology Trends

The surface mount LED technology represented by this device continues to evolve. General industry trends include ongoing improvements in luminous efficacy (more light output per watt of electrical input), which enhances energy efficiency. There is also a focus on improving color consistency and stability over the device's lifetime. Packaging technology advances aim to provide better thermal management, allowing for higher drive currents and power densities from increasingly smaller footprints. Furthermore, standardization of footprints and optical characteristics simplifies design-in for engineers across various lighting and display applications.