LTSA-S089ZWETU SMD LED Datasheet - Yellow Lens White Light - 50mA - 170mW - English Technical Documentation

1. Product Overview

The LTSA-S089ZWETU is a surface-mount device (SMD) light-emitting diode (LED) designed for automated printed circuit board (PCB) assembly and applications where space is a critical constraint. This component utilizes an InGaN (Indium Gallium Nitride) semiconductor to produce white light, which is then filtered through a yellow lens. It is engineered for reliability and performance in a variety of electronic equipment.

1.1 Core Features and Advantages

• Environmental Compliance: The product is compliant with the Restriction of Hazardous Substances (RoHS) directive.
• Packaging for Automation: Supplied in 8mm tape on 7-inch diameter reels, facilitating high-speed pick-and-place assembly processes.
• Moisture Sensitivity: Preconditioned to meet JEDEC Moisture Sensitivity Level 2a, ensuring reliability during the reflow soldering process.
• Automotive Qualification: The qualification process references the AEC-Q102 standard, which is the stress test qualification for discrete optoelectronic semiconductors in automotive applications.
• Standardized Package: Features an EIA (Electronic Industries Alliance) standard package outline.
• Compatibility: The device is I.C. (Integrated Circuit) compatible and suitable for use with automatic placement equipment.
• Soldering Process: Compatible with infrared (IR) reflow soldering processes, which is standard for lead-free assembly.

1.2 Target Market and Applications

The primary target market for this LED is the automotive industry, specifically for accessory applications. Its robust design and qualification make it suitable for the demanding environmental conditions found in vehicles. Potential use cases include interior lighting, dashboard indicators, switch backlighting, and other non-critical illumination functions within the vehicle cabin.

2. Technical Parameters: In-Depth Objective Interpretation

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed.

• Power Dissipation (Pd): 170 mW. This is the maximum amount of power the LED package can dissipate as heat without exceeding its thermal limits.
• Peak Forward Current (I_FP): 100 mA. This is the maximum allowable instantaneous current, typically specified under pulsed conditions (1/10 duty cycle, 0.1ms pulse width) to prevent overheating.
• DC Forward Current (I_F): 50 mA. This is the maximum continuous forward current recommended for reliable long-term operation.
• Operating & Storage Temperature Range: -40°C to +100°C. This wide range ensures functionality in harsh environments, from cold starts to hot engine compartments.

2.2 Thermal Characteristics

Thermal management is crucial for LED performance and lifespan. Excessive junction temperature leads to light output degradation and accelerated failure.

• Thermal Resistance, Junction-to-Ambient (R_θJA): 400 °C/W (Typical). Measured on an FR4 substrate with a 16mm² copper pad, this value indicates how effectively heat travels from the semiconductor junction to the surrounding air. A lower value is better.
• Thermal Resistance, Junction-to-Solder Point (R_θJS): 220 °C/W (Typical). This is often a more useful metric for design, as it measures the resistance from the junction to the PCB pads, where the heat is primarily conducted away. This value is critical for calculating the actual junction temperature during operation.
• Maximum Junction Temperature (T_J): 125 °C. The absolute upper limit for the temperature at the semiconductor junction.

2.3 Electro-Optical Characteristics at 25°C

These parameters are measured under standard test conditions (T_a=25°C, I_F=20mA) and define the device's performance.

• Luminous Flux (Φ_v): 7 lm (Typical), with a range of 6 to 8 lm. This is the total perceived power of light emitted.
• Luminous Intensity (I_v): 2450 mcd (Typical), with a range of 2100 to 2800 mcd. This is the amount of light power per solid angle (candela) measured along the central axis. The high value indicates a bright, focused output.
• Viewing Angle (2θ_1/2): 120 degrees (Typical). This is the full angle at which the luminous intensity drops to half of its axial value. A 120-degree angle provides a very wide beam, suitable for area illumination.
• Chromaticity Coordinates (x, y): (0.32, 0.31) Typical. These CIE 1931 coordinates define the white point color of the LED. A tolerance of ±0.01 is applied to these coordinates in the binning process.
• Forward Voltage (V_F): 2.8V to 3.4V at 20mA, with a typical value around the middle of this range. A tolerance of ±0.1V is applied within bins.
• ESD Withstand Voltage: 2 kV (Human Body Model, HBM). This rating indicates a moderate level of protection against electrostatic discharge, suitable for controlled manufacturing environments.

3. Binning System Explanation

To ensure consistent performance in production, LEDs are sorted into bins based on key parameters. The LTSA-S089ZWETU uses a three-code system: Vf / Iv / Color (e.g., D7/Y5/W30).

3.1 Forward Voltage (Vf) Binning

LEDs are grouped by their forward voltage drop at 20mA to ensure uniform brightness and current draw in parallel circuits or when driven by a constant voltage source.

• Bin D7: Vf = 2.8V to 3.0V
• Bin D8: Vf = 3.0V to 3.2V
• Bin D9: Vf = 3.2V to 3.4V

3.2 Luminous Intensity/Flux (Iv) Binning

This binning ensures a consistent light output level. Both luminous flux (lm) and axial luminous intensity (mcd) are specified for each bin.

• Bin Y5: 6.0-6.5 lm / 2100-2275 mcd
• Bin Y6: 6.5-7.0 lm / 2275-2450 mcd
• Bin Y7: 7.0-7.5 lm / 2450-2625 mcd
• Bin Y8: 7.5-8.0 lm / 2625-2800 mcd

A tolerance of ±10% is applied to the intensity/flux within each bin.

3.3 Color (Chromaticity) Binning

Color consistency is critical in applications where multiple LEDs are used together. Binning is done based on the CIE 1931 (x, y) chromaticity coordinates.

• Bin W30: This bin is defined by a quadrilateral on the CIE chart with corner points at (x,y): Point1 (0.312, 0.283), Point2 (0.306, 0.316), Point3 (0.331, 0.340), Point4 (0.331, 0.307). All LEDs within a production lot will have color coordinates falling within this region, with a tolerance of ±0.01.

4. Performance Curve Analysis

The datasheet provides a spatial distribution diagram (Fig. 2). This polar plot visually represents the 120-degree viewing angle, showing how the luminous intensity decreases as the observation angle moves away from the central axis (0°). The pattern is typically Lambertian or batwing for wide-angle LEDs, ensuring even illumination over a broad area rather than a narrow spotlight.

5. Mechanical and Package Information

5.1 Package Dimensions

The LED comes in an industry-standard SMD package. All dimensions are in millimeters with a standard tolerance of ±0.2mm unless otherwise specified. The package features a gold-plated version for enhanced solderability and corrosion resistance. The specific dimensional drawing is included in the original datasheet, detailing the length, width, height, and lead/pad spacing.

5.2 Recommended PCB Attachment Pad Layout

A land pattern design is provided for infrared or vapor phase reflow soldering. This recommended footprint ensures proper solder joint formation, thermal relief, and mechanical stability. Adhering to this design is critical for achieving the specified thermal performance (R_θJS).

5.3 Polarity Identification

The cathode is typically marked on the device body, often with a green tint, a notch, or a cut corner on the lens or package. The PCB silkscreen should clearly indicate the cathode pad to prevent reverse mounting during assembly.

6. Soldering and Assembly Guidelines

6.1 IR Reflow Soldering Profile

A detailed reflow profile is provided, compliant with J-STD-020 for lead-free processes. Key parameters include:

• Preheat: Ramp-up to 150-200°C.
• Soak/Preheat Time: Maximum of 120 seconds to allow for temperature equalization and flux activation.
• Peak Temperature: Maximum of 260°C. The time above liquidus (e.g., 217°C) should be controlled to minimize thermal stress on the LED package and epoxy lens.
• Cooling Rate: Controlled to prevent thermal shock.

6.2 Storage and Handling

As a Moisture Sensitivity Level (MSL) 2a device:

• Sealed Bag: Store at ≤30°C and ≤70% RH. Use within one year of the bag seal date.
• After Opening: Store at ≤30°C and ≤60% RH. It is recommended to complete IR reflow within 4 weeks of exposure.
• Extended Storage (Opened): Store in a sealed container with desiccant or in a nitrogen desiccator.
• Rebaking: If exposed for more than 4 weeks, bake at 60°C for at least 48 hours before soldering to remove absorbed moisture and prevent \"popcorning\" during reflow.

6.3 Cleaning

If cleaning is necessary after soldering, use only specified solvents. Immersing the LED in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute is acceptable. Avoid aggressive or unspecified chemicals that could damage the epoxy lens or package markings.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The LEDs are packaged in 8mm wide embossed carrier tape. The tape is wound onto a standard 7-inch (178mm) diameter reel. Each reel contains 2000 pieces. The packaging conforms to ANSI/EIA-481 specifications. Key dimensional details for the pocket size, tape pitch, and reel hub are provided in the datasheet drawings.

7.2 Label Information

The reel label includes the part number (LTSA-S089ZWETU) and the specific bin codes for Voltage (Vf), Intensity (Iv), and Color (e.g., D7/Y5/W30). This allows for precise traceability and selection for application requirements.

8. Application Suggestions and Design Considerations

8.1 Typical Application Scenarios

• Automotive Interior Lighting: Map lights, reading lights, footwell illumination, and general cabin ambient lighting.
• Indicator and Backlighting: Backlighting for buttons, switches, and instrument panel graphics. Status indicators for infotainment or climate control systems.
• Consumer Electronics: Suitable for devices requiring bright, wide-angle white illumination where automated assembly is used.

8.2 Critical Design Considerations

• Current Driving: Always drive the LED with a constant current source, not a constant voltage. The recommended operating current is 20mA for the specified optical characteristics. Exceeding 50mA DC will violate absolute maximum ratings.
• Thermal Design: Calculate the expected junction temperature (T_J) using the formula: T_J = T_A + (R_θJA × P_D), where P_D = V_F × I_F. Ensure T_J remains well below 125°C for reliability. Use the recommended PCB pad layout and adequate copper area for heat sinking.
• Optical Design: The 120-degree viewing angle provides very wide dispersion. For more focused light, secondary optics (lenses or reflectors) would be required.
• ESD Protection: While rated for 2kV HBM, implementing standard ESD protection measures on the PCB (e.g., transient voltage suppression diodes) is good practice, especially in automotive environments.

9. Technical Comparison and Differentiation

The LTSA-S089ZWETU differentiates itself through its combination of attributes tailored for automotive accessory markets:

• Automotive-Grade Qualification: Reference to AEC-Q102 is a key differentiator from commercial-grade LEDs, implying testing under more stringent environmental stress conditions (temperature cycling, humidity, etc.).
• Wide Operating Temperature: The -40°C to +100°C range exceeds typical commercial LED specifications, which often top out at +85°C.
• Specific Color Binning (W30): Provides a defined white point, which is crucial for applications requiring color consistency across multiple units.
• High Luminous Intensity: A typical 2450 mcd at 20mA is a relatively high output for a wide-angle SMD LED, offering good brightness efficiency.

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 Can I drive this LED at 50mA continuously?

While the Absolute Maximum Rating for DC forward current is 50mA, the Electro-Optical Characteristics are specified at 20mA. Operating at 50mA will produce more light but will also generate significantly more heat (Power Dissipation ~ Vf * 50mA). This will raise the junction temperature, potentially reducing lifespan and causing light output to degrade faster. It is essential to perform a thorough thermal analysis if intending to operate near the maximum current.

10.2 What is the difference between Luminous Flux (lm) and Luminous Intensity (mcd)?

Luminous Flux (lumens) measures the total amount of visible light emitted by the LED in all directions. Luminous Intensity (candelas) measures how bright the LED appears from a specific direction, typically along its central axis. This LED has high axial intensity (mcd) but also a wide beam (120°), resulting in a moderate total flux (lm). For area lighting, flux is more relevant; for a directed indicator, intensity is more relevant.

10.3 Why is the storage and baking procedure so important?

The epoxy-based package can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can vaporize rapidly, creating internal pressure. This can cause delamination between the epoxy and the lead frame or even crack the package (\"popcorning\"), leading to immediate or latent failure. Following the MSL 2a handling procedures prevents this failure mode.

11. Practical Application Case Study

Scenario: Designing an Automotive Center Console Backlight. A designer needs to illuminate several buttons and a small graphic display. They choose the LTSA-S089ZWETU for its automotive qualification, white light, and wide viewing angle. They design a PCB with the recommended pad layout, using a 20mA constant current driver IC for each LED. They select LEDs from the same intensity bin (e.g., Y6) and color bin (W30) to ensure uniform brightness and color across all buttons. The PCB is designed with a ground plane connected to the LED pads to aid heat dissipation. During assembly, the sealed reel is used within its floor life, and the IR reflow profile is strictly followed. The final product offers consistent, reliable illumination that meets the automotive temperature and longevity requirements.

12. Technology Principle Introduction

The LTSA-S089ZWETU is based on InGaN (Indium Gallium Nitride) semiconductor technology. In a white LED, a blue-emitting InGaN chip is coated with a phosphor layer. When the chip emits blue light, the phosphor absorbs a portion of it and re-emits light at longer wavelengths (yellow, red). The combination of the remaining blue light and the phosphor-converted light appears white to the human eye. The yellow lens then acts as a final filter, potentially tuning the color temperature or providing a specific aesthetic. This phosphor-converted white LED technology is efficient and allows for the creation of various white points.

13. Industry Trends and Developments

The trend in SMD LEDs for automotive and general lighting continues toward higher efficacy (more lumens per watt), improved color rendering index (CRI), and greater reliability at higher junction temperatures. There is also a move toward miniaturization of packages while maintaining or increasing light output. Furthermore, smart lighting systems integrating control electronics directly with LEDs are becoming more prevalent. For automotive interiors, dynamic ambient lighting with multi-color and dimming capabilities is a growing trend, though this specific component is a single-color, static solution suited for cost-effective, functional lighting applications.