LTLMR4TCY2DA Cyan LED Datasheet - 505nm - 25° Viewing Angle - 30mA - 105mW - English Technical Document

1. Product Overview

The LTLMR4TCY2DA is a high-brightness, cyan-emitting surface mount LED designed for demanding lighting applications. It utilizes advanced InGaN technology to produce light at a peak wavelength of 505nm, housed in a diffused package that provides a smooth radiation pattern. A key feature of this device is its inherent narrow viewing angle of typically 25 degrees, achieved through its package lens design without the need for additional secondary optics. This makes it particularly suitable for applications requiring precise light direction and control. The device is constructed using lead-free and halogen-free materials, is fully RoHS compliant, and is rated for Moisture Sensitivity Level 3 (MSL3) handling.

1.1 Core Advantages and Target Market

The primary advantages of this LED include its high luminous intensity output, ranging from 12,000 to 27,000 mcd at a standard 20mA drive current, coupled with low power consumption for high efficiency. The package offers superior moisture resistance and UV protection due to advanced epoxy technology. Its design is compatible with standard Surface Mount Technology (SMT) assembly lines and industrial reflow soldering processes. The target applications are primarily in signage where high visibility and controlled light distribution are critical, such as video message signs, traffic signs, and various other message display boards.

2. In-Depth Technical Parameter Analysis

This section provides a detailed breakdown of the operational limits and performance characteristics of the LED under standard test conditions (TA=25°C).

2.1 Absolute Maximum Ratings

The device must not be operated beyond these limits to prevent permanent damage. The maximum continuous DC forward current is 30 mA. For pulsed operation, a peak forward current of 100 mA is permissible under specific conditions (duty cycle ≤1/10, pulse width ≤10ms). The maximum power dissipation is 105 mW. The forward current rating derates linearly at 0.5 mA per degree Celsius above an ambient temperature of 45°C. The operating temperature range is from -40°C to +85°C, while the storage temperature range extends to +100°C. The device can withstand reflow soldering with a peak temperature of 260°C for a maximum of 10 seconds.

2.2 Electro-Optical Characteristics

Under a test condition of IF=20mA, the luminous intensity (Iv) has a typical range of 12,000 to 27,000 millicandelas (mcd). The viewing angle (2θ1/2), defined as the full angle at which intensity drops to half its axial value, is typically 25 degrees, with a minimum of 20 degrees. The peak emission wavelength (λP) is 505 nm. The dominant wavelength (λd), which defines the perceived color, ranges from 498 nm to 507 nm. The spectral line half-width (Δλ) is typically 28 nm, indicating the spectral purity of the cyan emission. The forward voltage (VF) at 20mA ranges from a minimum of 2.7V to a maximum of 3.6V. The reverse current (IR) is limited to a maximum of 10 μA at a reverse voltage (VR) of 5V; note that the device is not designed for operation under reverse bias.

3. Binning System Specification

To ensure color and brightness consistency in production, the LEDs are sorted into bins based on key parameters.

3.1 Luminous Intensity Binning

LEDs are classified into three intensity bins (Z, 1, 2) based on their luminous output at 20mA. Bin Z covers 12,000 to 16,000 mcd, Bin 1 covers 16,000 to 21,000 mcd, and Bin 2 covers 21,000 to 27,000 mcd. A tolerance of ±15% is applied to each bin limit during testing and guarantee.

3.2 Dominant Wavelength Binning

For color consistency, dominant wavelength is binned into two codes: C1 (498 nm to 503 nm) and C2 (503 nm to 507 nm). The tolerance for each bin limit is ±1 nm. This binning allows designers to select LEDs that match specific color point requirements for their application.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (Fig.1, Fig.6), their typical behavior can be described. The forward current vs. forward voltage (I-V) curve will exhibit the standard exponential diode characteristic. The luminous intensity is generally proportional to the forward current within the recommended operating range. The peak emission wavelength (λP) and dominant wavelength (λd) may exhibit minor shifts with changes in junction temperature and drive current, which is typical for semiconductor light sources. The narrow 25-degree viewing angle profile indicates a highly directional beam with rapid fall-off outside the central cone, which is advantageous for applications requiring high on-axis brightness and minimal light spill.

5. Mechanical and Package Information

5.1 Outline Dimensions and Tolerances

The LED comes in a surface-mount package. All dimensions are provided in millimeters, with a general tolerance of ±0.25mm unless otherwise specified. Key notes include: a maximum protrusion of resin under the flange of 1.0mm, and lead spacing measured at the point where leads emerge from the package body. Designers must refer to the detailed dimensional drawing for accurate footprint planning.

5.2 Recommended Solder Pad Pattern

A specific pad layout (P1, P2, P3) is recommended for PCB design. A critical design note is that one of the pads (P3) is intended to be connected to a heat sink or other cooling mechanism. This pad is designed to effectively distribute heat generated during operation, which is essential for maintaining performance and longevity, especially when operating at or near maximum ratings. The device is designed for reflow soldering and is not suitable for dip soldering processes.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A lead-free reflow profile is recommended. Key parameters include: a preheat/soak stage with temperature between 150°C and 200°C for a maximum of 120 seconds, a time above liquidus (T_L=217°C) between 60 and 150 seconds, and a peak temperature (T_P) of 260°C. The time within 5°C of the specified classification temperature (T_C=255°C) should not exceed 30 seconds. The total time from 25°C to peak temperature should be kept under 5 minutes. For manual rework with a soldering iron, the maximum temperature is 315°C for no more than 3 seconds, and this should be performed only once.

6.2 Storage and Moisture Sensitivity

This is an MSL3 device. LEDs in an unopened moisture barrier bag can be stored for up to 12 months at conditions below 30°C and 90% Relative Humidity (RH). After opening the bag, the components must be kept in an environment below 30°C and 60% RH, and all soldering must be completed 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 the devices have been exposed to >30°C and 60% RH. Baking should be performed only once. Prolonged exposure can oxidize the silver-plated leads, affecting solderability. Unused LEDs should be re-sealed with desiccant.

6.3 Cleaning

If cleaning is necessary after soldering, only alcohol-based solvents such as isopropyl alcohol (IPA) should be used. Harsh or aggressive chemical cleaners should be avoided as they may damage the epoxy lens or package markings.

7. Packaging and Ordering Information

7.1 Packaging Specification

The LEDs are supplied on embossed carrier tape and reel. The tape dimensions are specified, with pockets designed to hold the components securely. Each standard reel contains 1,000 pieces. For bulk packaging, 1 reel is placed in a moisture barrier bag along with a desiccant and humidity indicator card. Three such bags are packed into an inner carton (total 3,000 pcs). Ten inner cartons are then packed into an outer shipping carton, resulting in a total of 30,000 pieces per outer carton. The packaging is clearly marked as containing Electrostatic Sensitive Devices (ESD), requiring safe handling procedures.

8. Application Recommendations and Design Considerations

8.1 Typical Application Scenarios

The primary application for this LED is in various signage types, both indoor and outdoor. Its high brightness makes it suitable for video message signs and large-format information displays where sunlight readability may be a factor. The narrow, controlled viewing angle is ideal for traffic signs and directional message signs, ensuring the light is directed toward the viewer with high efficiency and minimal waste. It can also be used in ordinary electronic equipment requiring a bright cyan indicator or backlight.

8.2 Design Considerations

Current Driving: A constant current driver is strongly recommended over a constant voltage source to ensure stable light output and prevent thermal runaway. The design should operate the LED at or below the recommended 20mA for optimal lifetime, using the maximum 30mA only if absolutely necessary and with adequate thermal management.
Thermal Management: Despite its low power consumption, effective heat sinking is crucial for maintaining performance and reliability, especially in high ambient temperatures or densely packed arrays. The recommended connection of pad P3 to a thermal plane should be implemented.
Optical Design: The inherent 25-degree viewing angle often eliminates the need for additional lenses in many signage applications, simplifying the mechanical design. However, for applications requiring even narrower beams or specific distribution patterns, secondary optics can be used.
ESD Protection: As an ESD-sensitive device, proper handling procedures should be followed during assembly, including the use of grounded workstations and wrist straps.

9. Technical Comparison and Differentiation

Compared to standard SMD LEDs (like 3528 or 5050 packages) or PLCC (Plastic Leaded Chip Carrier) packages, the LTLMR4TCY2DA offers a significantly narrower native viewing angle. Standard SMD LEDs often have viewing angles of 120 degrees or more, requiring external lenses or reflectors to achieve a narrow beam. This integrated narrow-angle design simplifies the final product assembly, reduces component count, and can improve optical efficiency by minimizing light loss in secondary optics. Its high luminous intensity in a compact package also offers a competitive advantage in space-constrained, high-brightness applications.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the difference between peak wavelength (505nm) and dominant wavelength (498-507nm)?
A: Peak wavelength is the single wavelength at which the emitted optical power is highest. Dominant wavelength is derived from the color coordinates on the CIE diagram and represents the perceived color; it is the single wavelength that would match the LED's color if it were a pure monochromatic source. They are often close but not identical for LEDs with a spectral width.

Q: Can I drive this LED with a 3.3V supply?
A: Possibly, but not directly. The forward voltage ranges from 2.7V to 3.6V. Some LEDs may light dimly at 3.3V, while others with a higher Vf may not turn on at all. A constant current driver circuit is required for reliable and consistent operation.

Q: Why is the MSL3 rating and baking process important?
A: Moisture absorbed into the plastic package can vaporize rapidly during the high-temperature reflow soldering process, causing internal delamination, cracking, or "popcorning," which destroys the device. The MSL rating and associated handling procedures are critical for ensuring high assembly yield and long-term reliability.

Q: How do I interpret the bin codes (e.g., 2, C1)?
A: The bin code specifies the performance group. For example, "2, C1" indicates an LED from luminous intensity Bin 2 (21,000-27,000 mcd) and dominant wavelength Bin C1 (498-503 nm). Specifying bins allows designers to maintain brightness and color uniformity across their products.

11. Design and Usage Case Study

Scenario: Designing a High-Visibility Pedestrian Traffic Signal.
A design engineer is creating a "Walk/Don't Walk" signal that must be clearly visible in direct sunlight. They select the LTLMR4TCY2DA LED for the cyan "Walk" indicator. Due to the narrow 25-degree viewing angle, the LEDs can be arranged in a compact array behind a diffuser, ensuring bright, uniform illumination within the intended viewing zone for pedestrians, with minimal light pollution outside that zone. The high luminous intensity (selecting Bin 2 LEDs) guarantees sunlight readability. The designer implements a constant current driver set to 18mA to maximize lifetime and uses the recommended PCB pad layout, connecting the thermal pad to a large copper pour on the board for heat dissipation. They ensure the assembly house follows the MSL3 handling and the specified reflow profile to prevent moisture-related failures.

12. Operating Principle

The LTLMR4TCY2DA is a semiconductor light source based on Indium Gallium Nitride (InGaN) technology. When a forward voltage exceeding the diode's threshold is applied, electrons and holes are injected into the active region of the semiconductor chip. These charge carriers recombine, releasing energy in the form of photons (light). The specific composition of the InGaN material determines the bandgap energy, which in turn defines the wavelength of the emitted light—in this case, in the cyan region of the spectrum around 505 nm. The epoxy package encapsulates the chip, provides mechanical protection, incorporates a phosphor-less diffuser to shape the beam, and includes features for UV and moisture resistance.

13. Technology Trends

The surface-mount LED market continues to evolve toward higher efficiency (more lumens per watt), increased power density, and greater reliability. Trends relevant to this type of device include the ongoing refinement of InGaN materials for improved efficacy and color stability over temperature and lifetime. Packaging technology is advancing to provide better thermal management from the chip to the PCB, allowing for higher drive currents and brightness from smaller footprints. There is also a focus on enhancing moisture resistance to achieve higher MSL ratings, simplifying supply chain logistics. Furthermore, tighter binning tolerances for both color and flux are becoming standard to meet the demands of applications requiring precise color rendering and uniformity, such as full-color video displays.