SMD LED LTST-008UWQEET Datasheet - White & Red Colors - 30mA Forward Current - 102mW Power Dissipation - English Technical Document

1. Product Overview

This document details the specifications for a surface-mount device (SMD) LED component. This LED is designed for automated printed circuit board (PCB) assembly and is suitable for applications where space is a critical constraint. The component integrates two distinct light sources within a single package.

1.1 Features

• Compliant with RoHS environmental standards.
• Packaged on 12mm tape wound onto 7-inch diameter reels for automated handling.
• Standard EIA package footprint for compatibility.
• Input compatible with integrated circuit (IC) logic levels.
• Designed for compatibility with automated pick-and-place assembly equipment.
• Withstands standard infrared (IR) reflow soldering processes.
• Preconditioned to JEDEC Moisture Sensitivity Level 3.

1.2 Applications

The LED is intended for use in a broad range of electronic equipment and systems, including but not limited to:

• Telecommunication devices (e.g., cordless and cellular phones).
• Office automation equipment and notebook computers.
• Home appliances and consumer electronics.
• Network systems and industrial control equipment.
• Indoor signage and display applications.

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): 102 mW (White), 72 mW (Red). This is the maximum power the LED can dissipate as heat at an ambient temperature (Ta) of 25°C.
• Peak Forward Current (I_F(PEAK)): 100 mA (White), 80 mA (Red). This is the maximum allowable instantaneous current under pulsed conditions (1/10 duty cycle, 0.1ms pulse width).
• DC Forward Current (I_F): 30 mA for both colors. This is the maximum continuous forward current recommended for reliable operation.
• Operating Temperature Range: -40°C to +85°C. The device is designed to function within this ambient temperature range.
• Storage Temperature Range: -40°C to +100°C. The device can be stored without applied power within this range.

2.2 Electrical and Optical Characteristics

These parameters are measured at Ta=25°C and I_F=20mA, representing typical operating conditions.

• Luminous Flux (Φ_v): White: 4.15-11.4 lm (min-max). Red: 1.07-2.71 lm (min-max). This is the total visible light output of the LED.
• Luminous Intensity (I_v): White: 1500-4100 mcd (min-max). Red: 355-900 mcd (min-max). This is the light output in a specific direction, measured in millicandelas.
• Viewing Angle (2θ_1/2): Typically 120 degrees. This is the full angle at which the luminous intensity is half of its peak axial value.
• Dominant Wavelength (λ_d): For the Red LED: 617-630 nm (typical range). For the White LED, chromaticity coordinates are provided instead.
• Chromaticity Coordinates (x, y): For the White LED: x=0.31, y=0.31 (typical). This places the white point near the Planckian locus.
• Forward Voltage (V_F): White: 2.8-3.4V (min-max). Red: 1.8-2.4V (min-max). Tolerance is +/- 0.1V. This is the voltage drop across the LED when operating at the specified current.
• Reverse Current (I_R): Maximum 10 μA for both colors at V_R=5V. The device is not designed for reverse bias operation; this parameter is for test purposes only.

3. Binning System Explanation

The LEDs are sorted into performance bins to ensure consistency. The bin code is marked on the product packaging.

3.1 Luminous Intensity (I_v) Binning

LEDs are grouped based on their measured light output at 20mA.

White LED Bins:

• W1: Luminous Flux: 4.15-5.80 lm, Intensity: 1500-2100 mcd.
• W2: Luminous Flux: 5.80-8.10 lm, Intensity: 2100-2900 mcd.
• W3: Luminous Flux: 8.10-11.40 lm, Intensity: 2900-4100 mcd.

Red LED Bins:

• R1: Luminous Flux: 1.07-1.68 lm, Intensity: 355-600 mcd.
• R2: Luminous Flux: 1.68-2.71 lm, Intensity: 600-900 mcd.

Tolerance on each luminous bin is +/- 11%.

3.2 Color (Chromaticity) Binning for White LED

White LEDs are further sorted based on their chromaticity coordinates (x, y) on the CIE 1931 diagram to control color variation.

• Bin codes include Z1, Y1, Y2, X1, W1, W2.
• Each bin is defined by a quadrilateral area on the chromaticity diagram with four specific (x,y) coordinate points.
• Tolerance on each hue bin is +/- 0.01 in both x and y coordinates.

3.3 Combined Bin Code on Tag

A single alphanumeric code (A1 through A6) on the packaging tag combines the intensity bins for both the white and red LEDs within the same package, as shown in the cross-reference table.

4. Performance Curve Analysis

The datasheet includes typical characteristic curves measured at 25°C ambient temperature unless otherwise noted. These curves are essential for design analysis.

• Forward Current vs. Forward Voltage (I_F-V_F Curve): Shows the exponential relationship between current and voltage for both the white and red LEDs. This is critical for designing the current-limiting driver circuit.
• Luminous Intensity vs. Forward Current (I_v-I_F Curve): Illustrates how light output increases with drive current, typically in a sub-linear fashion at higher currents due to efficiency droop and heating.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the thermal dependence of light output. Luminous intensity generally decreases as the junction temperature rises.
• Spectral Distribution: For the red LED, this curve shows the relative radiant power as a function of wavelength, indicating the peak emission wavelength (λ_P) and spectral half-width (Δλ).
• Viewing Angle Pattern: A polar plot showing the angular distribution of luminous intensity, confirming the 120-degree viewing angle.

5. Mechanical and Package Information

5.1 Package Dimensions

The LED comes in a standard surface-mount package. All dimensions are in millimeters with a general tolerance of ±0.2 mm unless otherwise specified. The drawing shows the top view, side view, and footprint.

5.2 Pin Assignment and Polarity Identification

The component has multiple pins. The assignment is as follows:

• Pins (0,1) and 2: Connected to the Blue/White LED die (InGaN).
• Pins 3 and 4: Connected to the Red LED die (AlInGaP).
• Pins 5 and (6,7): Not connected (null).

The lens color is yellow. Proper polarity must be observed when connecting to the driver circuit; applying reverse voltage can damage the device.

5.3 Recommended PCB Attachment Pad Layout

A suggested land pattern (copper pad layout) for the PCB is provided to ensure reliable soldering, proper thermal management, and mechanical stability. Adhering to this recommendation helps prevent tombstoning and ensures good solder fillets.

6. Soldering and Assembly Guidelines

6.1 IR Reflow Soldering Profile

A detailed reflow soldering temperature profile is specified for lead-free (Pb-free) solder processes, compliant with J-STD-020B. The profile graph shows:

• Preheat/Ramp-up: A controlled rise to activate flux.
• Soak Zone: A plateau to evenly heat the board and component.
• Reflow Zone: Peak temperature must not exceed the maximum allowable for the component (linked to the storage temperature).
• Cooling Rate: A controlled descent to solidify the solder joints properly.

Following this profile is critical to prevent thermal shock and ensure reliable solder connections without damaging the LED package or internal die.

6.2 Cleaning

If cleaning after soldering is necessary:

• Use only ethyl alcohol or isopropyl alcohol.
• Immerse the LED at normal room temperature.
• Limit immersion time to less than one minute.
• Avoid using unspecified chemical cleaners as they may damage the package material (e.g., causing discoloration or cracking).

6.3 Storage and Handling Conditions

• Sealed Package: Store at ≤30°C and ≤70% Relative Humidity (RH). The shelf life is one year when stored in the original moisture-proof bag with desiccant.
• Opened Package: Storage ambient should not exceed 30°C and 60% RH. Components removed from their original packaging should undergo IR reflow soldering within 168 hours (7 days).
• Extended Storage (Out of Bag): For periods longer than 168 hours, store LEDs in a sealed container with desiccant or in a nitrogen-purged desiccator to prevent moisture absorption, which can cause "popcorning" during reflow.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The LEDs are supplied in embossed carrier tape for automated assembly.

• Tape Width: 12 mm.
• Reel Diameter: 7 inches.
• Quantity per Reel: 4000 pieces.
• Minimum Packing Quantity: 500 pieces for remainder quantities.
• Empty pockets in the tape are sealed with a top cover tape.
• A maximum of two consecutive missing components is allowed.
• Packaging conforms to ANSI/EIA-481 specifications.

Detailed dimensions for the tape pocket and the reel are provided in the datasheet.

8. Application Suggestions and Design Considerations

8.1 Typical Application Circuits

LEDs are current-driven devices. A series current-limiting resistor is the simplest drive method. The resistor value (R_s) can be calculated using Ohm's Law: R_s = (V_supply - V_F) / I_F. Use the maximum V_F from the datasheet to ensure the current does not exceed the limit even with component variation. For more stable performance, especially with varying supply voltage or temperature, constant current drivers (linear or switching) are recommended.

8.2 Thermal Management

While the power dissipation is relatively low, proper thermal design extends LED life and maintains stable light output.

• Use the recommended PCB pad layout to aid heat dissipation.
• In high-current or high-ambient-temperature applications, consider using thermal vias under the pad to transfer heat to inner or bottom copper layers.
• Ensure the maximum junction temperature is not exceeded by considering the thermal resistance from junction to ambient (θ_JA).

8.3 Optical Design Considerations

• The 120-degree viewing angle provides a wide, diffuse light pattern suitable for backlighting and status indicators.
• For more focused beams, secondary optics (lenses) can be placed over the LED.
• The yellow lens acts as a color filter/diffuser for the white light, potentially affecting the exact Correlated Color Temperature (CCT).

9. Technical Comparison and Differentiation

This component's primary differentiation lies in its dual-color (white and red) configuration within a single SMD package. This saves PCB space and simplifies assembly compared to using two separate LEDs. Key points include:

• Space Efficiency: Integrates two functions into one footprint.
• Assembly Simplicity: One placement cycle instead of two.
• Performance: Offers distinct, independently addressable white and red light sources with specified performance bins for each.
• Compatibility: Standard EIA footprint and compatibility with IR reflow make it a drop-in solution for modern SMT lines.

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 Can I drive the LED with a 5V supply directly?

No. Connecting a 5V supply directly across the LED would cause excessive current flow, likely destroying it. You must use a current-limiting mechanism, such as a series resistor or a constant-current driver, set for a maximum of 30mA DC.

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 viewing direction. The mcd value in the datasheet is typically the axial (on-axis) intensity. A wide-viewing-angle LED may have high lumens but lower mcd compared to a narrow-beam LED with the same lumens.

10.3 How do I interpret the bin codes when ordering?

Specify the combined bin code (e.g., A3) from the cross-table to ensure you receive LEDs with the desired performance range for both the white (e.g., W2) and red (e.g., R1) components. This is crucial for applications requiring consistent brightness and color across multiple units.

10.4 Is this LED suitable for outdoor use?

The operating temperature range extends to -40°C, but the maximum is +85°C. While it could function in some outdoor environments, the datasheet primarily lists indoor applications (signage, displays). For outdoor use, consider potential exposure to UV radiation, moisture ingress, and higher ambient temperatures, which may require additional protective measures not covered in this document.

11. Practical Design and Usage Case

Scenario: Dual-Status Indicator for a Network Router

A designer needs power (steady white) and network activity (blinking red) indicators on a compact router PCB.

Implementation:

1. Component Selection: The LTST-008UWQEET is chosen because it provides both required colors in one 3.2mm x 2.8mm footprint, saving space.
2. Circuit Design: Two independent driver circuits are designed:
   • A simple resistor from a 3.3V rail to drive the white LED at ~15mA for a constant "power on" indicator.
   • A GPIO pin from the main processor, also with a series resistor, drives the red LED. The firmware blinks this pin to indicate data activity.
3. PCB Layout: The recommended pad layout is used. Thermal relief connections are added to the pads to facilitate soldering while maintaining a thermal path to a ground plane for slight heat dissipation.
4. Binning: For consistency across production units, bin code A3 (White: W2, Red: R1) is specified in the Bill of Materials (BOM), ensuring all routers have similarly bright indicators.
5. Assembly: The parts are supplied on 7" reels compatible with the assembly line's pick-and-place machine. The specified IR reflow profile is programmed into the oven.

This case highlights the component's utility in space-constrained, multi-function indicator applications common in consumer electronics.

12. Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light when an electric current passes through them. This phenomenon is called electroluminescence.

• White LED: Typically, a blue LED chip made of Indium Gallium Nitride (InGaN) is coated with a phosphor layer. The blue light from the chip excites the phosphor, which then emits yellow light. The combination of blue and yellow light is perceived as white by the human eye. The yellow lens may further modify this output.
• Red LED: The red light is generated directly by a semiconductor chip made of Aluminum Indium Gallium Phosphide (AlInGaP). When electrons recombine with holes in the semiconductor material, energy is released in the form of photons (light). The specific composition of the material determines the wavelength (color) of the emitted light, in this case, red (~630 nm).

The forward voltage (V_F) is characteristic of the semiconductor material's bandgap energy; a higher bandgap (blue/white) results in a higher V_F than a lower bandgap (red).

13. Development Trends

The field of SMD LEDs continues to evolve with several clear trends:

• Increased Efficiency (lm/W): Ongoing material science and chip design improvements yield more light output per unit of electrical power, reducing energy consumption and thermal load.
• Higher Reliability and Lifetime: Advancements in packaging materials, die attach techniques, and phosphor stability are extending operational lifetimes, making LEDs suitable for more critical applications.
• Miniaturization: Packages continue to shrink (e.g., from 3528 to 2016 to 1010 sizes) while maintaining or improving optical performance, enabling denser and more compact electronic designs.
• Improved Color Quality and Consistency: Tighter binning tolerances and new phosphor formulations lead to better color rendering index (CRI) for white LEDs and more saturated, consistent colors for monochromatic LEDs.
• Integrated Solutions: Beyond multi-color packages, trends include LEDs with integrated drivers (ICs), built-in Zener diodes for ESD protection, and packages designed for specific optical patterns, reducing the need for external components.

Components like the one described in this datasheet represent an intermediate step in integration, combining multiple discrete functions into a single, reliable, and manufacturable package.