LTW-K140SXR85 LED Datasheet - EIA Package - 3.2V - 0.28W - 8500K White - English Technical Document

1. Product Overview

The product is a wide beam angle, standard-dimension surface-mount device (SMD) LED package. It is designed to combine the long lifetime and high reliability inherent to Light Emitting Diodes with a brightness level suitable for displacing conventional lighting technologies in various applications. The package offers design flexibility and is intended for integration into automated assembly processes.

1.1 Key Features

• Packaged in 8mm tape on 7-inch diameter reels for automated handling.
• Fully compatible with standard automatic pick-and-place equipment.
• Suitable for both infrared (IR) and vapor phase reflow soldering processes.
• Conforms to EIA (Electronic Industries Alliance) standard package dimensions.
• Designed to be compatible with integrated circuit (IC) drive levels.
• Manufactured as a green product and is lead-free, complying with RoHS (Restriction of Hazardous Substances) directives.

1.2 Available Part Number

The specific part number covered in this document is LTW-K140SXR85, which corresponds to a white LED with a correlated color temperature (CCT) of 8500 Kelvin (K).

2. Mechanical and Package Information

The device utilizes a standard EIA package outline. The lens color is yellow, and the light source is based on InGaN (Indium Gallium Nitride) technology emitting blue light, which is converted to white light by the phosphor coating in the yellow lens.

Notes:

• All dimensional drawings and tolerances are provided in millimeters.
• The standard tolerance for dimensions is ±0.1 mm unless explicitly stated otherwise on the drawing.

3. Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. All values are specified at an ambient temperature (Ta) of 25°C.

Important Notes:

• The device must not be operated under reverse voltage conditions for extended periods.
• The pulse forward current rating (105 mA) applies under specific conditions: a 1/10 duty cycle and a pulse width not exceeding 100 microseconds (μs).

4. Electro-Optical Characteristics

This section details the key performance parameters of the LED under typical operating conditions, primarily at a forward current (I_F) of 60 mA.

4.1 Typical Performance Data

Critical Application Notes:

• Luminous Flux (Φ_v): Represents the total visible light output measured with an integrating sphere. A classification code is marked on each packing bag.
• Chromaticity (x, y): Derived from the 1931 CIE chromaticity diagram. A tolerance of ±0.01 should be applied to the typical coordinates.
• Electrostatic Discharge (ESD): LEDs are sensitive to ESD. Proper handling procedures using wrist straps, anti-static gloves, and grounded equipment are mandatory to prevent damage.
• Measurement Tolerances: Luminous flux measurement has an allowance of ±10%. Forward voltage measurement has an allowance of ±0.1 V.
• Thermal Management: The junction-to-solder pad thermal resistance (R_jt) is a critical parameter. A reference value of 30°C/W is given when mounted on a specified 2.5x2.5x0.17 cm Aluminum Metal Core PCB (MCPCB). Proper heatsinking is essential to maintain junction temperature within limits and ensure performance and longevity.

4.2 Performance Curve Analysis

The datasheet provides several graphical representations of device performance:

• Relative Spectral Power Distribution: Shows the intensity of light emitted at each wavelength, defining the color characteristics of the 8500K white light.
• Radiation Pattern / Viewing Angle Characteristic: Illustrates the angular distribution of light intensity, confirming the wide 120-degree viewing angle.
• Forward Current vs. Forward Voltage (I-V Curve): Essential for circuit design, showing the relationship between drive current and the voltage drop across the LED. The curve is non-linear, typical of diode behavior.
• Relative Luminous Flux vs. Junction Temperature: Demonstrates how light output decreases as the LED's junction temperature increases. This highlights the importance of thermal management.
• Forward Voltage vs. Junction Temperature: Shows the slight variation in forward voltage with changes in junction temperature.

5. Binning and Classification System

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

5.1 Color Binning

LEDs are classified into specific chromaticity regions (ranks) on the CIE 1931 diagram. The datasheet defines coordinates for ranks L1 and L5. A tolerance of ±0.01 applies to the (x, y) coordinates within each defined bin.

5.2 Luminous Flux Binning

LEDs are sorted based on their total light output at 60 mA.

Tolerance on luminous flux is ±10%.

5.3 Forward Voltage Binning

LEDs are also sorted by their forward voltage drop at 60 mA.

Tolerance on forward voltage is ±0.1 V.

5.4 Bin Code and Labeling

A complete bin code is formed by combining the ranks from each category: Voltage / Flux / Color (e.g., V1/S0/L1). This full code is indicated on the product label for traceability and selection.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

The device is compatible with lead-free reflow soldering processes. The recommended profile is crucial to prevent thermal damage.

6.2 Critical Assembly Notes

• Soldering Methods: Reflow soldering is primary. Hand soldering is possible but limited to 350°C for a maximum of 2 seconds, for one time only. Reflow can be performed up to three times maximum at the specified peak conditions.
• Temperature Reference: All profile temperatures refer to the top side of the package body.
• Moisture Sensitivity: LEDs are moisture-sensitive. If removed from their original dry-packaging for more than 168 hours (1 week), they must be baked at 60°C for 60 minutes before soldering to prevent \"popcorning\" or delamination during reflow.
• Storage: For extended storage outside the original bag, use a sealed container with desiccant or a nitrogen environment.
• Cooling: Avoid rapid cooling (quenching) from peak temperature.
• General Rule: Always use the lowest possible soldering temperature that achieves a reliable joint.
• Wave/Dip Soldering: This method is not recommended or guaranteed for this SMD package.

7. Reliability Test Data

The product has undergone a series of standardized reliability tests. The results demonstrate robustness under various environmental and operational stresses. All tests listed were conducted with a sample size of 20 pieces, and zero failures were reported.

8. Application Suggestions and Design Considerations

8.1 Typical Application Scenarios

• General Indicator Lighting: Status indicators, power-on lights, backlighting for panels or switches.
• Decorative and Architectural Lighting: Accent lighting, contour lighting, and other applications where a wide, even beam is desirable.
• Consumer Electronics: Backlighting for small displays, keyboard illumination, or decorative elements in devices.
• Automotive Interior Lighting: Map lights, footwell illumination, or other non-exterior applications (subject to further qualification for automotive standards).

8.2 Critical Design Considerations

• Current Driving: Always drive the LED with a constant current source, not a constant voltage. The typical drive current is 60 mA, but the circuit must limit the maximum current to 80 mA continuous. A series current-limiting resistor used with a voltage source is a simple method, but for stability over temperature and voltage variations, a dedicated LED driver IC is recommended.
• Thermal Management: This is the most critical aspect of LED design for performance and lifetime. The 280 mW power dissipation (at 60 mA, 3.2V = 192 mW typical) must be effectively conducted away from the LED junction. Use the provided thermal resistance data (R_jt=30°C/W) to calculate the necessary heatsinking to keep T_j below 100°C. For example, on the reference MCPCB, with an ambient of 50°C and 192 mW dissipation, T_j would be approximately 50°C + (0.192W * 30°C/W) = 55.8°C, which is safe.
• Optical Design: The 120-degree viewing angle provides a very wide, diffuse beam. For applications requiring a more focused beam, secondary optics (lenses or reflectors) would be necessary.
• ESD Protection: Incorporate ESD protection diodes on PCB traces connected to the LED, especially in environments prone to static discharge.
• Binning for Consistency: For applications requiring uniform color or brightness across multiple LEDs, specify tight bins (e.g., a single color rank and flux bin) when ordering.

9. Technical Comparison and Trends

9.1 Product Positioning

The LTW-K140SXR85 represents a mature, standardized SMD LED package. Its key advantages are its compatibility with automated assembly, proven reliability, and wide availability. Compared to newer, smaller packages (e.g., 0402, 0201), it offers higher light output and potentially better thermal performance due to its larger size. Compared to larger, high-power LED packages, it is easier to integrate and requires less complex drive and thermal management circuitry.

9.2 Industry Context

The move towards lead-free (RoHS compliant) and green manufacturing is fully embraced in this product. The specified reflow profile aligns with modern lead-free assembly processes used across the electronics industry. The trend in solid-state lighting continues towards higher efficacy (more lumens per watt), but this standard package remains relevant for applications where ultra-high efficiency is less critical than cost, reliability, and ease of use.