SMD LED LTST-008UWVSWT Datasheet - Dual Color White & Yellow - 30mA - 102mW - English Technical Document

1. Product Overview

This document provides the technical specifications for a surface-mount device (SMD) Light Emitting Diode (LED) identified as LTST-008UWVSWT. This component is a dual-color LED, integrating both a white light source and a yellow light source within a single, compact package. SMD LEDs are designed for automated printed circuit board (PCB) assembly processes, offering advantages in manufacturing efficiency and enabling use in space-constrained applications.

1.1 Features

• Compliant with RoHS (Restriction of Hazardous Substances) directives.
• Packaged in industry-standard 12mm tape on 7-inch diameter reels for automated handling.
• EIA standard package footprint.
• Integrated Circuit (IC) compatible drive characteristics.
• Fully compatible with automatic pick-and-place assembly equipment.
• Suitable for use with infrared (IR) reflow soldering processes.
• Preconditioned to accelerate to JEDEC Moisture Sensitivity Level 3.

1.2 Applications

This LED is suitable for a broad range of electronic equipment where status indication, backlighting, or decorative lighting is required. Typical application areas include:

• Telecommunication equipment (e.g., cordless phones, cellular phones).
• Office automation devices (e.g., notebook computers, network systems).
• Home appliances.
• Industrial equipment.
• Signage and indoor display applications.

2. Package Dimensions and Pin Assignment

The LED is housed in a standard SMD package. All dimensions are provided in millimeters (mm) with a general tolerance of ±0.2 mm unless otherwise specified. The component features multiple pins for independent control of the two light sources.

Pin Assignment for LTST-008UWVSWT:

• White LED (InGaN Blue source): Connected to pins (0,1) and 2.
• Yellow LED (AlInGaP source): Connected to pins 3 and 4.
• Pins 5, 6, and 7 are noted as null (no connection).

Detailed mechanical drawings specifying length, width, height, and pad spacing are included in the datasheet. The recommended PCB attachment pad layout is also provided to ensure proper soldering and thermal management.

3. Ratings and Characteristics

3.1 Absolute Maximum Ratings

Stresses beyond these limits may cause permanent damage to the device. All ratings are specified at an ambient temperature (Ta) of 25°C.

3.2 Electrical and Optical Characteristics

Typical performance parameters measured at Ta=25°C and a forward current (I_F) of 20mA.

Notes:

1. Luminous flux is measured with a sensor/filter approximating the CIE photopic eye-response curve.
2. Luminous intensity (in millicandelas) is provided for reference.
3. Viewing angle is the full angle where intensity drops to half its axial value.
4. Dominant wavelength defines the perceived color on the CIE chromaticity diagram.
5. Forward voltage tolerance is ±0.1V.
6. The device is not designed for reverse bias operation; this test is for IR qualification only.

4. Binning System

The LEDs are sorted (binned) according to key optical parameters to ensure consistency within a production lot. The binning information is critical for design and procurement.

4.1 Luminous Intensity (I_V) Binning

Both white and yellow LEDs are grouped into bins based on their luminous flux and corresponding luminous intensity at 20mA. Each bin has a tolerance of ±11%.

White LED Bins:

• W1: 4.15 - 5.80 lm (1500 - 2100 mcd)
• W2: 5.80 - 8.10 lm (2100 - 2900 mcd)
• W3: 8.10 - 11.40 lm (2900 - 4100 mcd)

Yellow LED Bins:

• Y1: 1.25 - 1.80 lm (450 - 650 mcd)
• Y2: 1.80 - 2.60 lm (650 - 930 mcd)
• Y3: 2.60 - 3.75 lm (930 - 1350 mcd)

4.2 Combined Bin Code

A single alphanumeric code (A1 through A9) on the product tag combines the white and yellow intensity bins (e.g., A1 = W1 & Y1, A4 = W2 & Y1).

4.3 Color Binning

Yellow Dominant Wavelength: Binned into two ranges: AU (585-590 nm) and AV (590-595 nm), with a tolerance of ±1 nm.

White Chromaticity: The white LED's color point on the CIE 1931 chromaticity diagram is binned into several zones (Z1, Y1, Y2, X1, W1, W2), defined by specific (x, y) coordinate boundaries. The tolerance for each hue bin is ±0.01 in both x and y coordinates. A chromaticity diagram is provided in the datasheet for visual reference.

5. Typical Performance Curves

The datasheet includes graphical representations of key characteristics to aid in circuit design and understanding device behavior under various conditions. These curves typically include:

• Relative Luminous Intensity vs. Forward Current: Shows how light output increases with current for both colors.
• Forward Voltage vs. Forward Current: Illustrates the IV relationship.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the thermal derating of light output.
• Spectral Distribution: Likely shown for the yellow LED, indicating the peak emission wavelength and spectral width.

These curves are essential for predicting performance in real-world applications where current or temperature may vary.

6. User Guide and Assembly Information

6.1 Cleaning

Unspecified chemical cleaners may damage the LED package. If cleaning after soldering is necessary, immerse the LED in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute.

6.2 Soldering Process

The LED is compatible with infrared (IR) reflow soldering processes. A suggested reflow profile for lead-free (Pb-free) solder, compliant with J-STD-020B, is provided. This profile defines the critical temperature zones (preheat, soak, reflow peak, cooling) and their time/temperature limits to ensure reliable solder joints without damaging the LED.

6.3 Packaging: Tape and Reel

The components are supplied in embossed carrier tape with a protective cover tape, wound onto 7-inch (178mm) diameter reels. Key packaging specifications include:

• Pocket pitch and dimensions for automated feeding.
• Reel hub diameter, flange diameter, and width.
• Standard quantity: 4000 pieces per reel.
• Minimum order quantity for remnants: 500 pieces.
• Compliance with ANSI/EIA-481 specifications.

7. Cautions and Application Notes

7.1 Intended Use and Reliability

These LEDs are designed for use in standard electronic equipment. For applications requiring exceptional reliability where failure could jeopardize life or health (e.g., aviation, medical devices, safety systems), specific consultation and qualification are necessary prior to design-in.

7.2 Storage and Handling

• Sealed Package: Store at ≤30°C and ≤70% Relative Humidity (RH). The components have a recommended use-within period of one year when the moisture-proof bag with desiccant remains sealed.
• Opened Package: If the moisture barrier bag is opened, the storage environment must not exceed 30°C and 60% RH. Components exposed to ambient conditions should undergo IR reflow soldering within 168 hours (7 days) to prevent moisture-induced damage (\"popcorning\") during reflow.

8. Design Considerations and Technical Analysis

8.1 Driving the LED

To ensure stable light output and long lifetime, drive the LED with a constant current source, not a constant voltage. The recommended operating current is 20mA, with an absolute maximum DC current of 30mA. The different forward voltages (V_F) of the white (~3.2V typ.) and yellow (~2.3V typ.) LEDs must be considered when designing the driving circuit, especially if they are to be powered from the same voltage rail. A series current-limiting resistor or a dedicated LED driver IC is typically required.

8.2 Thermal Management

While SMD LEDs are efficient, a portion of the input power is dissipated as heat. The maximum power dissipation is 102mW for the white LED and 84mW for the yellow LED. Proper PCB thermal design, including adequate copper pad area and possible thermal vias, is important to maintain the junction temperature within safe limits, especially at high ambient temperatures or drive currents. The derating curve (Relative Luminous Intensity vs. Temperature) shows that light output decreases as temperature rises.

8.3 Optical Design

The wide viewing angle (130° for white) makes this LED suitable for applications requiring broad illumination or wide-angle visibility. For applications needing a more focused beam, secondary optics (e.g., lenses) would be required. The dual-color nature allows for creating bi-color status indicators (e.g., white for \"on,\" yellow for \"standby/charge\") in a single component footprint, saving board space.

8.4 Binning in System Design

The provided binning information is crucial for achieving consistent color and brightness in a final product, especially when multiple LEDs are used in an array or for backlighting. Designers should specify the required bin codes to their supplier to ensure the LEDs meet the aesthetic and functional requirements of the application. Mixing bins from different lots may result in visible color or brightness variations.