SMD LED LTSA-E67RVEWTU Datasheet - Diffused Red AlInGaP - 70mA - 185.5mW - English Technical Document

1. Product Overview

This document provides the complete technical specifications for a surface-mount device (SMD) Light Emitting Diode (LED). The component is designed for automated printed circuit board (PCB) assembly and is suitable for space-constrained applications. Its primary characteristics include a diffused lens and a red light source based on Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor technology.

1.1 Core Features and Target Market

The LED is engineered with several key features that enhance its reliability and ease of integration. It is compliant with the Restriction of Hazardous Substances (RoHS) directive. The component is supplied in industry-standard packaging: on 8mm tape wound onto 7-inch diameter reels, facilitating high-speed automated pick-and-place assembly. It has undergone preconditioning to JEDEC Moisture Sensitivity Level 2a, ensuring robustness against moisture-induced damage during reflow soldering. Furthermore, the product is qualified according to the AEC-Q101 Rev. D standard, a critical benchmark for components used in automotive electronics. Its design is compatible with infrared (IR) reflow soldering processes. The primary target application is automotive accessory systems, where reliability and performance under varying environmental conditions are paramount.

2. Technical Parameters: In-Depth Objective Interpretation

This section details the absolute limits and operational characteristics of the LED. Understanding these parameters is essential for reliable circuit design and ensuring the component operates within its safe operating area (SOA).

2.1 Absolute Maximum Ratings

The absolute maximum ratings define the stress limits beyond which permanent damage to the device may occur. These ratings are specified at an ambient temperature (Ta) of 25°C. The maximum continuous DC forward current (IF) is 70 mA. Under pulsed conditions with a 1/10 duty cycle and a 0.1ms pulse width, the device can handle a peak forward current of 100 mA. The maximum power dissipation (Pd) is 185.5 mW. The device is rated for an operating and storage temperature range of -40°C to +100°C. For lead-free soldering processes, it can withstand an infrared reflow profile with a peak temperature of 260°C for a maximum of 10 seconds.

2.2 Thermal Characteristics

Thermal management is crucial for LED performance and longevity. The thermal resistance from the semiconductor junction to the ambient air (RθJA) is typically 280 °C/W, measured on a standard FR4 PCB with a 1.6mm thickness and a copper pad area of 16mm². The thermal resistance from the junction to the solder point (RθJS) is typically 130 °C/W, providing a more direct path for heat sinking. The maximum allowable junction temperature (Tj) is 125°C. Exceeding this temperature will accelerate lumen depreciation and can lead to catastrophic failure.

2.3 Electro-Optical Characteristics

The electro-optical characteristics are measured at Ta=25°C and a test current (IF) of 50 mA, which is a common operating point below the absolute maximum. The luminous intensity (Iv) ranges from a minimum of 1800 millicandelas (mcd) to a maximum of 3550 mcd. The viewing angle (2θ½), defined as the full angle at which the luminous intensity drops to half of its axial value, is 120 degrees, indicating a wide, diffuse emission pattern. The peak emission wavelength (λP) is 632 nm. The dominant wavelength (λd), which defines the perceived color, has a specified range of 618 nm to 630 nm. The spectral bandwidth (Δλ) is approximately 20 nm. The forward voltage (VF) at 50 mA ranges from 1.9V to 2.65V. The reverse current (IR) is limited to a maximum of 10 μA when a reverse voltage (VR) of 12V is applied; it is important to note that the device is not designed for operation in reverse bias.

3. Bin Ranking System Explanation

To ensure consistency in color and brightness for production applications, LEDs are sorted into performance bins. The batch is labeled with a code representing its forward voltage (Vf), luminous intensity (Iv), and dominant wavelength (Wd) ranks.

3.1 Forward Voltage (Vf) Binning

Forward voltage is binned in steps of approximately 0.15V. Bin codes range from C (1.90V - 2.05V) to G (2.50V - 2.65V). A tolerance of ±0.1V is applied to each bin. Selecting LEDs from the same Vf bin helps maintain uniform current distribution when multiple devices are connected in parallel.

3.2 Luminous Intensity (Iv) Binning

Luminous intensity is categorized into three bins: X1 (1800-2240 mcd), X2 (2240-2800 mcd), and Y1 (2800-3550 mcd). A tolerance of ±11% applies to each bin. This allows designers to select the appropriate brightness level for their application.

3.3 Dominant Wavelength (Wd) Binning

The dominant wavelength, which determines the precise shade of red, is binned in 3nm steps. Bin codes are 5 (618-621 nm), 6 (621-624 nm), 7 (624-627 nm), and 8 (627-630 nm). The tolerance for each bin is ±1 nm. This tight control is essential for applications requiring specific color points.

4. Performance Curve Analysis

Graphical data provides insight into how the LED behaves under varying conditions, which is critical for robust system design.

4.1 Current vs. Voltage (I-V) Characteristic

The forward voltage exhibits a logarithmic relationship with forward current. At low currents, the voltage is close to the diode's built-in potential. As current increases, the voltage rises due to the series resistance of the semiconductor material and contacts. Designers must use this curve to select appropriate current-limiting resistors or driver circuits to ensure the LED operates at the desired brightness without exceeding its maximum ratings.

4.2 Luminous Intensity vs. Forward Current

The luminous intensity is generally proportional to the forward current in the normal operating range. However, efficiency may drop at very high currents due to increased heat generation and other non-radiative recombination processes. Operating the LED significantly above its recommended current will reduce its lifespan.

4.3 Temperature Dependence

The performance of an LED is highly temperature-dependent. As the junction temperature increases, the forward voltage typically decreases slightly for a given current. More significantly, the luminous output decreases. The dominant wavelength may also shift slightly with temperature. Effective heat sinking is therefore essential to maintain consistent optical performance, especially in high-power or high-ambient-temperature applications like automotive environments.

5. Mechanical and Packaging Information

5.1 Physical Dimensions and Polarity Identification

The LED conforms to a standard EIA package outline. All critical dimensions are provided in millimeters, with a general tolerance of ±0.2 mm unless otherwise specified. A key design note is that the anode lead frame also serves as the primary heat sink for the LED. Proper identification of the anode and cathode is crucial during PCB layout and assembly to ensure correct polarity connection.

5.2 Recommended PCB Pad Layout

A recommended land pattern (footprint) for the PCB is provided to ensure reliable soldering and optimal thermal performance. This pattern is designed for compatibility with infrared reflow soldering processes. Adhering to this recommended layout helps achieve proper solder fillets, ensures mechanical stability, and maximizes heat transfer from the LED's thermal pad (anode) to the PCB.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A detailed infrared reflow soldering profile is specified for lead-free processes, in accordance with the J-STD-020 standard. The profile includes pre-heat, thermal soak, reflow, and cooling stages. The critical parameter is a peak package body temperature not exceeding 260°C, sustained for a maximum of 10 seconds. Following this profile is essential to prevent thermal damage to the LED's epoxy lens and internal semiconductor structure.

6.2 Storage and Handling Precautions

The product is classified as Moisture Sensitivity Level (MSL) 2a per JEDEC J-STD-020. While in its original, sealed moisture-barrier bag with desiccant, it should be stored at ≤30°C and ≤70% RH and used within one year. Once the bag is opened, the components should be stored at ≤30°C and ≤60% RH. It is recommended to complete the IR reflow process within 4 weeks of opening the bag. For storage beyond 4 weeks outside the original packaging, components should be stored in a sealed container with desiccant or baked at approximately 60°C for at least 48 hours prior to soldering to remove absorbed moisture and prevent "popcorning" during reflow.

6.3 Cleaning

If cleaning after soldering is necessary, only specified solvents should be used. Immersing the LED in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute is acceptable. The use of unspecified or aggressive chemical cleaners can damage the LED's plastic package and optical lens.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The LEDs are supplied on embossed carrier tape with a width of 8mm. 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. Detailed dimensions for the tape pockets, cover tape, and reel are provided to ensure compatibility with automated assembly equipment.

8. Application Notes and Design Considerations

8.1 Typical Application Scenarios

The primary intended application is for automotive accessory functions. This can include interior ambient lighting, dashboard indicator lights, center console illumination, or external marker lights where a diffuse, wide-angle red emission is required. Its AEC-Q101 qualification makes it suitable for the harsh environmental conditions (temperature, humidity, vibration) found in vehicles.

8.2 Critical Design Considerations

Current Limiting: An LED is a current-driven device. A series resistor or constant-current driver circuit is mandatory to limit the forward current to a safe value, typically at or below the recommended 50-70 mA range, accounting for power supply variations.
Thermal Management: The maximum junction temperature must not be exceeded. Design the PCB layout to provide an adequate thermal path from the anode pad. For high-current or high-ambient-temperature applications, consider using a larger copper area on the PCB or additional thermal vias to dissipate heat.
ESD Protection: While not explicitly stated for this device, AlInGaP LEDs can be sensitive to electrostatic discharge (ESD). Implementing standard ESD handling precautions during assembly is recommended.
Optical Design: The 120° viewing angle and diffused lens provide a soft, wide beam. For applications requiring a more focused beam, secondary optics (e.g., lenses, light guides) would be necessary.

9. Technical Comparison and Differentiation

This AlInGaP-based red LED offers specific advantages. Compared to older technologies like Gallium Arsenide Phosphide (GaAsP), AlInGaP provides higher luminous efficiency, resulting in greater brightness for the same input current. The diffused lens creates a uniform, wide emission pattern ideal for area illumination rather than focused spot lighting. The AEC-Q101 qualification and MSL 2a rating are key differentiators for automotive and other demanding applications, indicating enhanced reliability testing and moisture resistance compared to standard commercial-grade LEDs.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED directly from a 5V or 12V supply?
A: No. You must use a current-limiting mechanism. For a 5V supply, a series resistor is commonly used (R = (Vsupply - Vf) / If). For a 12V supply, a resistor would dissipate excessive heat; a constant-current driver or a switching regulator is recommended.

Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λP) is the wavelength at which the spectral power distribution is maximum (632 nm). Dominant wavelength (λd) is the single wavelength of monochromatic light that would match the perceived color of the LED (618-630 nm). λd is more relevant for color specification.

Q: Why is the thermal resistance important?
A: It quantifies how effectively heat can escape from the LED junction. A lower thermal resistance means better heat dissipation, which allows you to drive the LED at higher currents or in hotter environments while keeping the junction temperature within safe limits, thereby ensuring long-term reliability and stable light output.

Q: The datasheet mentions a reverse voltage test. Can I use this LED in an AC circuit or with reverse polarity protection?
A: The 12V reverse voltage rating is for test purposes only. The device is not designed for continuous reverse bias operation. In an AC circuit or for polarity protection, an external series diode must be used to block reverse voltage across the LED.

11. Practical Design and Usage Example

Scenario: Designing a red status indicator for an automotive control module. The module operates from the vehicle's 12V battery system (nominal 14V when running). The indicator needs to be clearly visible in daylight.
Design Steps:
1. Current Selection: Choose an operating point of 50 mA for a good balance of brightness and longevity.
2. Driver Selection: Due to the high supply voltage, a simple resistor would waste over 0.5W of power. A better solution is a low-dropout (LDO) constant-current LED driver IC set to 50 mA.
3. Thermal Design: The module may be located in the engine bay. Estimate the maximum ambient temperature (e.g., 85°C). Calculate the expected junction temperature rise: ΔTj = Pd * RθJA = (VF * IF) * RθJA. Using typical VF=2.2V and RθJA=280°C/W, Pd=0.11W, so ΔTj ≈ 31°C. Tj = Ta + ΔTj = 85°C + 31°C = 116°C, which is below the 125°C maximum. This is acceptable but marginal. To improve reliability, increase the copper area on the PCB pad connected to the anode to lower the effective RθJA.
4. Bin Selection: For consistent appearance across multiple units in a dashboard, specify tight bins for dominant wavelength (e.g., Bin 7) and luminous intensity (e.g., Bin X2 or Y1).

12. Operating Principle Introduction

Light Emitting Diodes are semiconductor p-n junction devices. When a forward voltage is applied, electrons from the n-type region and holes from the p-type region are injected across the junction. These charge carriers recombine in the active region of the semiconductor. In a direct bandgap semiconductor like AlInGaP, a significant portion of this recombination event releases energy in the form of photons (light). The specific wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor material. AlInGaP alloys are engineered to produce light in the red, orange, and yellow parts of the visible spectrum. The diffused lens is made of an epoxy or silicone material that contains scattering particles. These particles randomly redirect the light emitted from the semiconductor chip, broadening the beam angle and creating a more uniform, softer appearance by eliminating the bright central "hot spot" typical of a clear-lens LED.

13. Technology Trends and Developments

The field of LED technology is continuously evolving. For indicator and signaling applications like this component, trends focus on several key areas. Increased Efficiency: Ongoing material science research aims to improve the internal quantum efficiency (IQE) of AlInGaP and other semiconductor materials, yielding higher luminous output per unit of electrical input power (lm/W). Enhanced Reliability: Demands from automotive and industrial markets drive improvements in package materials (e.g., high-temperature silicones) and die-attach technologies to withstand higher junction temperatures and more extreme thermal cycling. Miniaturization: There is a constant push for smaller package footprints while maintaining or increasing optical power, enabling denser integration in modern electronic devices. Color Consistency and Binning: Advances in epitaxial growth and manufacturing process control allow for tighter distributions of wavelength and luminous intensity, reducing the need for extensive binning and simplifying inventory management for manufacturers. Integrated Solutions: A growing trend is the integration of the LED die with driver ICs, protection components (like ESD diodes), and even control logic into single, smart package modules.