SMD LED LTSA-E67RUWETU Datasheet - White InGaN, Yellow Lens - 50mA, 170mW - English Technical Document

1. Product Overview

The LTSA-E67RUWETU is a high-brightness, surface-mount LED designed for automated assembly processes and space-constrained applications. It features a white light source utilizing InGaN (Indium Gallium Nitride) technology, housed within a yellow-tinted lens package. This combination is engineered to meet the demands of modern electronic equipment requiring reliable, compact illumination solutions.

1.1 Core Advantages and Target Market

This LED is characterized by its compatibility with automated pick-and-place equipment and standard infrared (IR) reflow soldering processes, making it ideal for high-volume manufacturing. Its primary target markets include consumer electronics, network systems, and notably, automotive accessory applications. The device is qualified according to the AEC-Q101 standard (Revision D), underscoring its suitability for automotive environments where component reliability is paramount. Additional features include RoHS compliance, packaging on 8mm tape within 7-inch reels, and preconditioning to JEDEC Moisture Sensitivity Level 2a, ensuring stability during storage and assembly.

2. In-Depth Technical Parameter Analysis

A detailed examination of the electrical, optical, and thermal specifications is crucial for proper circuit design and thermal management.

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. They are specified at an ambient temperature (Ta) of 25°C. The maximum continuous forward current (DC) is 50 mA. Under pulsed conditions (1/10 duty cycle, 0.1ms pulse width), a peak forward current of 100 mA is permissible. The maximum power dissipation is 170 mW. The device is rated for an operating and storage temperature range of -40°C to +100°C. Exceeding these limits, especially the junction temperature, can lead to catastrophic failure or significant degradation in light output and lifespan.

2.2 Electrical and Optical Characteristics

Measured at Ta=25°C and a standard test current (IF) of 30mA, the device exhibits a typical luminous intensity ranging from a minimum of 1800 mcd to a maximum of 3550 mcd. The forward voltage (VF) typically falls between 2.8V and 3.4V, with a stated tolerance of ±0.1V per voltage bin. The viewing angle (2θ1/2), defined as the angle where intensity is half the axial value, is 120 degrees, indicating a wide, diffuse light emission pattern. The chromaticity coordinates are specified as x=0.3197, y=0.3131 on the CIE 1931 diagram, defining its white point. The reverse current (IR) is a maximum of 10 µA at VR=5V, and the Electrostatic Discharge (ESD) withstand voltage is 2000V using the Human Body Model (HBM). It is critical to note that the device is not designed for operation under reverse bias; the reverse voltage test condition is for informational purposes only.

2.3 Thermal Characteristics

Effective thermal management is essential for LED performance and longevity. The thermal resistance from the junction to ambient (RθJA) is typically 280 °C/W, measured on an FR4 substrate with a 1.6mm thickness and a 16mm² copper pad. More importantly, the thermal resistance from the junction to the solder point (RθJS) is 130 °C/W. This lower value is more relevant for design as it represents the primary heat conduction path from the LED chip to the printed circuit board (PCB). The absolute maximum junction temperature (TJ) is 125°C. Designers must ensure that the operating junction temperature, calculated using the power dissipation and thermal resistances, remains well below this limit to ensure reliability.

3. Binning System Explanation

The LTSA-E67RUWETU employs a comprehensive binning system to categorize units based on forward voltage (VF), luminous intensity (IV), and color coordinates. This allows designers to select LEDs with consistent performance for their application.

3.1 Forward Voltage (VF) Binning

Units are sorted into three voltage bins: H (2.8V - 3.0V), J (3.0V - 3.2V), and K (3.2V - 3.4V). A tolerance of ±0.1V is applied to each bin. Selecting LEDs from the same VF bin helps ensure uniform current distribution when multiple LEDs are connected in parallel.

3.2 Luminous Intensity (IV) Binning

Intensity bins ensure consistent brightness levels. The bins are: X1 (1800 - 2240 mcd), X2 (2240 - 2800 mcd), and Y1 (2800 - 3550 mcd). A tolerance of ±11% is applied within each bin. This allows for grading based on output requirements, potentially affecting cost and selection for different product tiers.

3.3 Color Coordinate Binning

The most complex aspect is color binning. The datasheet provides a detailed table of chromaticity coordinates defining multiple quadrilateral regions (bins) on the CIE 1931 chart, such as LL, LK, ML, MK, NL, NK, etc. Each bin is defined by four (x, y) coordinate points. The typical color point (x=0.3197, y=0.3131) falls within several of these bins (e.g., LL, LK, ML). A tolerance of ±0.01 is specified for the hue coordinates within a bin. This tight control is vital for applications where color consistency is critical, such as in indicator clusters or backlighting where multiple LEDs are viewed simultaneously.

4. Mechanical and Packaging Information

4.1 Package Dimensions and Polarity

The LED conforms to an EIA standard SMD package outline. All dimensions are provided in millimeters with a general tolerance of ±0.2 mm unless otherwise specified. A critical design note is that the anode lead frame also functions as the primary heat sink for the LED. This means the anode pad on the PCB must be designed with adequate thermal mass and possibly connected to thermal vias or planes to effectively dissipate heat. Proper identification of the anode and cathode during layout is essential for correct operation and optimal thermal performance.

4.2 Recommended PCB Attachment Pad

The datasheet includes a diagram for the recommended solder pad layout on the PCB for infrared reflow soldering. Adhering to these dimensions ensures a reliable solder joint, proper alignment, and effective heat transfer from the LED's thermal pad (anode) to the PCB.

4.3 Tape and Reel Packaging

For automated assembly, the LEDs are supplied on 8mm wide embossed carrier tape wound onto 7-inch (178mm) diameter reels. Each reel contains 2000 pieces. The packaging conforms to ANSI/EIA-481 specifications. Key notes include: empty component pockets are sealed with cover tape, and a maximum of two consecutive missing components (lamps) is allowed per reel. Understanding the tape pitch and reel dimensions is necessary for programming automated assembly equipment.

5. Soldering, Assembly, and Handling Guide

5.1 IR Reflow Soldering Profile

A suggested reflow profile for lead-free solder processes is provided, aligned with the J-STD-020 standard. This profile typically includes preheat, thermal soak, reflow (with a peak temperature limit), and cooling stages. Following the manufacturer's recommended profile is critical to prevent thermal shock, solder joint defects, or damage to the LED's internal structure and epoxy lens.

5.2 Cleaning

If post-solder cleaning is required, only specified chemicals should be used. The datasheet recommends immersion in ethyl alcohol or isopropyl alcohol at normal room temperature for less than one minute. The use of unspecified or aggressive chemicals can damage the LED's package material, leading to discoloration, cracking, or delamination.

5.3 Storage and Moisture Sensitivity

The product is classified as Moisture Sensitivity Level (MSL) 2a per JEDEC J-STD-020. This means the sealed moisture-proof bag (with desiccant inside) has a floor life of 4 weeks after opening when stored at conditions ≤ 30°C / 60% RH. For long-term storage before use, the sealed bags should be kept at 30°C or less and 70% relative humidity or less. The LEDs have a recommended use-within period of one year while in the sealed moisture-proof package. Failure to observe these precautions can lead to \"popcorning\" during reflow, where absorbed moisture vaporizes and cracks the package.

6. Application Notes and Design Considerations

6.1 Typical Application Scenarios

This LED is suitable for a wide range of electronic equipment, including but not limited to: cordless and cellular phones, notebook computers, networking systems, and various automotive accessory applications (e.g., interior lighting, switch backlighting, status indicators). Its AEC-Q101 qualification makes it a candidate for non-safety-critical automotive electronics.

6.2 Design Considerations

• Current Limiting: Always use a series current-limiting resistor or a constant-current driver. The forward voltage has a range (2.8-3.4V), so designing for the maximum VF ensures the LED does not exceed its current rating when connected to a fixed voltage source.
• Thermal Management: The anode is the thermal path. Design the PCB anode pad with sufficient copper area. Use thermal vias to connect to internal or bottom-side ground/power planes for heat spreading. Calculate the expected junction temperature using P_Dissipated = VF * IF and ΔT = RθJS * P_Dissipated.
• ESD Protection: While rated for 2kV HBM, implementing standard ESD protection measures on PCB inputs and during handling is considered good practice, especially in non-controlled environments.

6.3 Important Cautions

The datasheet explicitly states that these LEDs are intended for ordinary electronic equipment. For applications requiring exceptional reliability where failure could jeopardize life or health (e.g., aviation, medical devices, transportation safety systems), consultation with the manufacturer is required prior to design-in. This is a standard disclaimer highlighting the component's intended use case.

7. Technical Deep Dive and Analysis

7.1 Principle of Operation

The LTSA-E67RUWETU utilizes an InGaN (Indium Gallium Nitride) semiconductor chip to produce white light. Typically, this is achieved by using a blue-emitting InGaN die coated with a yellow phosphor. Some of the blue light is converted by the phosphor to yellow light; the mixture of blue and yellow light is perceived by the human eye as white. The yellow-tinted external lens may serve to further modify the color temperature or diffuse the light output, creating the final perceived color specified by the chromaticity coordinates.

7.2 Performance Curve Analysis

The datasheet includes a spatial distribution (radiation pattern) curve (Fig. 2). This curve graphically represents the luminous intensity as a function of viewing angle, confirming the 120-degree viewing angle specification. It shows a Lambertian-like distribution, common for LEDs with a diffuse lens, where intensity is highest at 0 degrees (on-axis) and decreases smoothly towards the edges.

7.3 Answering Common Technical Questions

Q: Can I drive this LED with 3.3V directly?
A: Not reliably without a current-limiting mechanism. Since VF can be as high as 3.4V, a 3.3V source may not turn on some units in the higher voltage bins (K bin). For units with a lower VF (e.g., 2.9V), applying 3.3V directly would cause excessive current flow, potentially exceeding the 50mA maximum and damaging the LED. Always use a series resistor or constant-current driver.

Q: How do I interpret the color bin codes like \"LL\" or \"MK\"?
A> These are arbitrary labels for specific quadrilaterals on the CIE chromaticity diagram defined in the color bin table. They represent tight groupings of color points. For consistent appearance in an assembly, specify and use LEDs from the same color bin code.

Q: What is the significance of the RθJS value being lower than RθJA?
A> RθJA includes the resistance from the junction to the solder point PLUS the resistance from the PCB to the ambient air. RθJS isolates the performance of the LED package and its attachment to the board. A lower RθJS means the LED itself is relatively efficient at getting heat into the PCB. The ultimate cooling performance depends heavily on the PCB design (copper area, layers, airflow).