LTLMR4EVX3DA LED Lamp Datasheet - Size 4.2x4.2x6.9mm - Voltage 1.8-2.4V - Power 120mW - Red 626nm - English Technical Document

1. Product Overview

The LTLMR4EVX3DA is a high-brightness surface mount LED lamp designed for demanding illumination applications. It utilizes a red AllnGaP chip with a peak emission wavelength of 626nm, housed in a red diffused package. This device is engineered to deliver superior luminous intensity output while maintaining low power consumption and high efficiency.

The core advantage of this LED lies in its integrated optical design. The package features a specific lens geometry that provides a controlled, narrow viewing angle (typically 35°), eliminating the need for additional external optics in many sign board applications. This results in a smooth radiation pattern ideal for message displays. Furthermore, the component is constructed using advanced epoxy technology, which offers excellent moisture resistance and UV protection, enhancing its reliability for both indoor and outdoor use. The product is fully compliant with RoHS directives, being lead-free and halogen-free.

The target market primarily includes manufacturers of electronic signage, such as video message signs, traffic signs, and various information display boards where consistent, bright, and focused red illumination is required.

2. Technical Parameter Analysis

2.1 Absolute Maximum Ratings

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

• Power Dissipation (Pd): 120 mW maximum. This is the total power the package can dissipate as heat at an ambient temperature (TA) of 25°C.
• DC Forward Current (IF): 50 mA maximum under continuous operation.
• Peak Forward Current: 120 mA maximum, but only under pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 10µs).
• Derating: The maximum DC forward current must be linearly reduced by 0.75 mA for every degree Celsius the ambient temperature rises above 45°C.
• Operating Temperature Range: -40°C to +85°C. The device is rated to function within this environmental temperature range.
• Storage Temperature Range: -40°C to +100°C.
• Reflow Soldering Condition: Withstands a peak temperature of 260°C for a maximum of 10 seconds, compatible with standard lead-free reflow processes.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters measured at TA=25°C and IF=20mA, unless otherwise specified.

• Luminous Intensity (Iv): Ranges from a minimum of 5500 mcd to a typical maximum of 12000 mcd. The Iv value is measured using a sensor filtered to match the CIE photopic eye-response curve. A ±15% testing tolerance is applied to guaranteed values.
• Viewing Angle (2θ1/2): 35° typical (30° min, 40° max). This is the full angle at which the luminous intensity drops to half of its axial (center) value. Measurement tolerance is ±2°.
• Peak Emission Wavelength (λP): 634 nm typical. This is the wavelength at the highest point of the emission spectrum.
• Dominant Wavelength (λd): Between 618 nm and 630 nm. This is the single wavelength perceived by the human eye, calculated from the CIE chromaticity coordinates, defining the color as red.
• Spectral Line Half-Width (Δλ): 15 nm typical. This indicates the spectral purity or bandwidth of the emitted light.
• Forward Voltage (VF): Between 1.8 V and 2.4 V at IF=20mA. This is the voltage drop across the LED when operating.
• Reverse Current (IR): 10 µA maximum when a reverse voltage (VR) of 5V is applied. Important: This device is not designed for reverse bias operation; this test is for characterization only.

3. Binning System Specification

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

3.1 Luminous Intensity (Iv) Binning

LEDs are classified into three intensity bins at IF=20mA. The bin code is marked on the packaging.

• Bin W: 5500 mcd (Min) to 7200 mcd (Max)
• Bin X: 7200 mcd (Min) to 9300 mcd (Max)
• Bin Y: 9300 mcd (Min) to 12000 mcd (Max)

Tolerance on each bin limit is ±15%.

3.2 Forward Voltage (VF) Binning

LEDs are also binned according to their forward voltage drop at IF=20mA.

• Bin 1A: 1.8 V (Min) to 2.0 V (Max)
• Bin 2A: 2.0 V (Min) to 2.2 V (Max)
• Bin 3A: 2.2 V (Min) to 2.4 V (Max)

Tolerance on each bin limit is ±0.1V.

4. Performance Curve Analysis

While specific graphical curves are not detailed in the provided text, typical performance trends for such LEDs can be inferred from the electrical/optical characteristics section. Key relationships include:

• IV Curve (Current vs. Voltage): The forward voltage (VF) exhibits a logarithmic relationship with forward current (IF). Operating at the recommended 20mA ensures the device stays within its specified VF range and power dissipation limits.
• Luminous Intensity vs. Current (Iv-IF): Luminous intensity generally increases with forward current but may become sub-linear at very high currents due to efficiency droop and thermal effects. Operating at or below the specified DC current is crucial for maintaining performance and longevity.
• Temperature Dependence: Luminous intensity typically decreases as the junction temperature increases. The derating specification for forward current above 45°C is a direct measure to manage this thermal effect and prevent overheating.
• Spectral Distribution: The emission spectrum is centered around 634nm (peak) with a typical half-width of 15nm, indicating a relatively narrowband red light source. The dominant wavelength (618-630nm) determines the perceived color point.

5. Mechanical & Package Information

5.1 Outline Dimensions

The LTLMR4EVX3DA is a surface mount device with the following key dimensions (in millimeters, with inches in brackets):

• Package Body Size: 4.2 ±0.2 [0.17±0.01] (Length) x 4.2 ±0.2 [0.17±0.01] (Width).
• Total Height: 6.9 ±0.5 [0.27±0.02].
• Lead (Terminal) Width: 0.45 [0.02].
• Lead Spacing (Pitch): Measured where leads emerge from the package. Protruded resin under the flange is a maximum of 1.0mm [0.04\"].

General tolerance is ±0.25mm [.010\"] unless otherwise specified.

5.2 Polarity Identification & Pad Design

The device has three terminals: P1 (Anode), P2 (Cathode), and P3 (Anode). The dual-anode configuration is common for thermal and electrical design flexibility. A recommended solder pad pattern is provided to ensure proper soldering and thermal management. Pad P3 is specifically recommended to be connected to a heat sink or cooling mechanism to aid in heat dissipation during operation, which is critical for maintaining performance and reliability.

6. Soldering & Assembly Guidelines

6.1 Storage & Handling (MSL3)

This component is classified as Moisture Sensitivity Level 3 (MSL3) per JEDEC J-STD-020.

• Storage in Sealed Bag: Can be stored for up to 12 months at <30°C and 90% RH.
• Floor Life: After opening the moisture barrier bag, components must be soldered within 168 hours (7 days) when kept under <30°C / 60% RH conditions.
• Baking: Required if the humidity indicator card shows >10% RH, floor life exceeds 168 hours, or parts are exposed to >30°C / 60% RH. Recommended bake condition: 60°C ±5°C for 20 hours. Baking should be performed only once.
• Unused LEDs should be stored with desiccant in a resealed moisture barrier bag to prevent oxidation of the silver-plated leads.

6.2 Soldering Parameters

Reflow Soldering (Recommended):

• Pre-heat: 150–200°C
• Pre-heat Time: 120 seconds maximum.
• Peak Temperature: 260°C maximum.
• Time at Peak: 10 seconds maximum.
• Maximum Number of Reflows: 2.

Hand Soldering (Iron):

• Iron Temperature: 315°C maximum.
• Soldering Time: 3 seconds maximum per joint.
• Maximum Number of Hand Soldering Cycles: 1.

Important Notes: This LED is designed for reflow soldering, not dip soldering. Avoid applying external stress during soldering while the LED is hot, and avoid rapid cooling from peak temperature.

6.3 Cleaning

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

7. Packaging & Ordering Information

The LTLMR4EVX3DA is supplied in embossed carrier tape for automated pick-and-place assembly. The tape dimensions are specified to be compatible with standard SMT equipment. Each reel contains a total of 1,000 pieces. The packing specification ensures components are protected and oriented correctly during shipping and handling.

8. Application Notes & Design Considerations

8.1 Typical Applications

• Video message signs and large-format displays.
• Traffic signals and road signage.
• Information and advertising message boards.
• Other electronic equipment requiring high-brightness, focused red indicators.

8.2 Drive Circuit Design

LEDs are current-operated devices. To ensure uniform brightness when driving multiple LEDs, especially in parallel configurations, it is strongly recommended to use a current-limiting resistor in series with each LED (Circuit Model A). Driving LEDs in parallel without individual current regulation (Circuit Model B) is not recommended, as small variations in the forward voltage (VF) characteristic between individual LEDs can lead to significant differences in current sharing and, consequently, uneven brightness.

8.3 Thermal Management

Proper thermal design is essential. Exceeding the maximum junction temperature will reduce light output and shorten lifespan. Utilize the recommended pad pattern, connecting the thermal pad (P3) to a copper pour or dedicated heat sink on the PCB to effectively dissipate the 120mW maximum power.

9. Technical Comparison & Differentiation

The LTLMR4EVX3DA differentiates itself from standard SMD or PLCC-type LEDs through its integrated optical design. The package itself provides a controlled, narrow viewing angle (35°), which is a key advantage for sign board applications. This eliminates the cost, complexity, and alignment issues associated with adding secondary external lenses to achieve a focused beam. The combination of high luminous intensity, a pre-defined radiation pattern, and robust moisture-resistant packaging makes it a specialized solution optimized for signage, compared to general-purpose LEDs with wider viewing angles.

10. Frequently Asked Questions (FAQ)

Q1: Can I drive this LED without a current-limiting resistor?
A1: No. An LED must be driven with a controlled current. Connecting it directly to a voltage source will cause excessive current to flow, potentially destroying the device instantly. Always use a series resistor or a constant-current driver.

Q2: Why is the viewing angle important for sign applications?
A2: A narrow, controlled viewing angle ensures that light is directed towards the viewer and not wasted illuminating areas outside the intended viewing zone. This increases the perceived brightness and efficiency of the sign, especially for directed viewing.

Q3: What does MSL3 mean, and why is baking necessary?
A3: MSL3 indicates the component can absorb moisture from the air. During reflow soldering, this trapped moisture can rapidly turn to steam, causing internal delamination or \"popcorning,\" which damages the package. Baking removes this absorbed moisture before the high-temperature soldering process.

Q4: Can I use this LED for reverse-voltage indication?
A4: No. The device is not designed for reverse operation. The reverse current (IR) specification is for test purposes only. Applying a continuous reverse voltage will likely damage the LED.

11. Practical Design Case Study

Consider designing a compact \"EXIT\" sign. The design requires bright, uniform red illumination across the letters. Using the LTLMR4EVX3DA, an array of LEDs can be placed behind a diffuser panel. Due to its 35° viewing angle, the light from each LED will be focused forward, minimizing spillage and ensuring high efficiency. Each LED in the array would be driven in a series-parallel configuration, with each series string having a common current-limiting resistor, powered by a stable DC supply. The narrow beam helps maintain uniform brightness across the sign face without hotspots. The MSL3 rating necessitates planning the assembly process to complete soldering within the 168-hour floor life after opening the reel.

12. Operational Principle

Light Emitting Diodes (LEDs) are semiconductor devices that emit light through electroluminescence. When a forward voltage is applied across the p-n junction, electrons and holes recombine in the active region (composed of AllnGaP for red light). This recombination releases energy in the form of photons (light particles). The specific wavelength (color) of the light is determined by the bandgap energy of the semiconductor material. The diffused package contains phosphors or scattering particles within the encapsulant to widen the light extraction and create a more uniform appearance from the emitting surface.

13. Technology Trends

The general trend in LED technology for signage and illumination continues towards higher efficacy (more lumens per watt), improved color consistency, and greater reliability. Packaging technology is evolving to better manage heat extraction, allowing for higher drive currents and greater light output from smaller footprints. There is also a focus on developing materials and structures that maintain performance over wider temperature ranges and longer lifetimes. For colored LEDs like the red AllnGaP type, research aims at improving the efficiency at higher current densities and enhancing the stability of the color point over time and operating conditions.