LTST-S326TGKRKT Dual Color SMD LED Datasheet - Side Looking - Green/Red - 20mA/30mA - English Technical Document

1. Product Overview

This document provides the complete technical specifications for a dual-color, side-looking Surface Mount Device (SMD) LED. The component integrates two distinct semiconductor chips within a single package: an InGaN (Indium Gallium Nitride) chip for green emission and an AlInGaP (Aluminum Indium Gallium Phosphide) chip for red emission. This design allows for the generation of two colors from a single compact device, making it suitable for applications requiring status indication, backlighting, or decorative lighting in space-constrained environments. The side-emitting lens configuration directs light parallel to the mounting plane, which is ideal for edge-lit panels or indicators viewed from the side.

The LED is designed for high-volume automated assembly processes. It is supplied on standard 8mm tape mounted on 7-inch diameter reels, compatible with pick-and-place equipment. The device is also compliant with infrared (IR) reflow soldering processes, adhering to industry-standard profiles for lead-free (Pb-free) assembly. The package features a water-clear lens, which does not diffuse the light, resulting in high-intensity, focused output from the side of the component.

2. Absolute Maximum Ratings

The absolute maximum ratings define the limits beyond which permanent damage to the device may occur. These values are specified at an ambient temperature (Ta) of 25°C and must not be exceeded under any operating conditions.

• Power Dissipation (Pd): 76 mW for the Green chip, 75 mW for the Red chip. This is the maximum amount of power the LED can dissipate as heat.
• Peak Forward Current (I_FP): 100 mA for Green, 80 mA for Red. This is the maximum allowable current under pulsed conditions, specified at a 1/10 duty cycle and a 0.1ms pulse width. Exceeding this can cause immediate chip degradation.
• DC Forward Current (I_F): 20 mA for Green, 30 mA for Red. This is the maximum continuous forward current recommended for reliable long-term operation.
• Operating Temperature Range: -20°C to +80°C. The device is guaranteed to function within this ambient temperature range.
• Storage Temperature Range: -30°C to +100°C. The device can be stored without applied power within these limits.
• Infrared Soldering Condition: The package can withstand a peak temperature of 260°C for a maximum of 10 seconds during reflow soldering.

3. Electrical and Optical Characteristics

The following parameters are measured at Ta=25°C under the specified test conditions and represent the typical performance of the device.

3.1 Luminous Intensity and Viewing Angle

• Luminous Intensity (I_V): Measured at I_F = 20 mA.
  • Green (InGaN): Minimum 45.0 mcd, Typical 150.0 mcd.
  • Red (AlInGaP): Minimum 18.0 mcd, Typical 100.0 mcd.
  Luminous intensity is measured using a sensor and filter combination that approximates the photopic (human eye) response curve (CIE).
• Viewing Angle (2θ_1/2): Typically 130 degrees for both colors. This is the full angle at which the luminous intensity drops to half of its value measured directly on-axis (0 degrees). A wide viewing angle of 130° indicates a broad, diffuse emission pattern suitable for side illumination.

3.2 Spectral Characteristics

• Peak Emission Wavelength (λ_P): The wavelength at which the optical output power is greatest.
  • Green: Typically 520 nm.
  • Red: Typically 639 nm.
• Dominant Wavelength (λ_d): The single wavelength perceived by the human eye that defines the color. It is derived from the CIE chromaticity coordinates.
  • Green: Typically 525 nm.
  • Red: Typically 631 nm.
• Spectral Line Half-Width (Δλ): The bandwidth of the emitted light measured at half the maximum intensity (Full Width at Half Maximum - FWHM).
  • Green: Typically 15 nm.
  • Red: Typically 20 nm.
  A narrower half-width indicates a more spectrally pure color.

3.3 Electrical Parameters

• Forward Voltage (V_F): Measured at I_F = 20 mA.
  • Green: Typical 3.5 V, Maximum 3.8 V.
  • Red: Typical 2.0 V, Maximum 2.4 V.
  The significant difference in V_F between the two chips is due to their different semiconductor material bandgaps (InGaN has a wider bandgap than AlInGaP). This must be considered in circuit design, especially when driving both colors from a common voltage source.
• Reverse Current (I_R): Maximum 10 μA for both colors at a Reverse Voltage (V_R) of 5V. Important Note: This parameter is for test purposes only. The LED is not designed for operation under reverse bias. Applying a reverse voltage in a circuit can damage the device.

4. Binning System Explanation

The luminous intensity of LEDs can vary from batch to batch. A binning system is used to sort devices into groups (bins) based on their measured performance, ensuring consistency for the end-user. The tolerance for each intensity bin is +/-15%.

4.1 Green Chip Intensity Bins

Luminous Intensity measured at 20 mA, unit: millicandela (mcd).

• Bin P: 45.0 mcd (Min) to 71.0 mcd (Max)
• Bin Q: 71.0 mcd to 112.0 mcd
• Bin R: 112.0 mcd to 180.0 mcd
• Bin S: 180.0 mcd to 280.0 mcd
• Bin T: 280.0 mcd to 450.0 mcd

4.2 Red Chip Intensity Bins

Luminous Intensity measured at 20 mA, unit: millicandela (mcd).

• Bin M: 18.0 mcd (Min) to 28.0 mcd (Max)
• Bin N: 28.0 mcd to 45.0 mcd
• Bin P: 45.0 mcd to 71.0 mcd
• Bin Q: 71.0 mcd to 112.0 mcd
• Bin R: 112.0 mcd to 180.0 mcd

When specifying or ordering this component, the specific bin codes for intensity (and potentially wavelength/color) may be part of the full part number to guarantee a certain performance level.

5. Mechanical and Package Information

The device conforms to EIA (Electronic Industries Alliance) standard package dimensions for SMD components. Detailed mechanical drawings are provided in the datasheet, including:

• Package Outline Drawing: Shows the top, side, and bottom views with all critical dimensions in millimeters. Tolerances are typically ±0.10 mm unless otherwise noted.
• Pin Assignment:
  • Cathode 1 (C1): Connected to the Red AlInGaP chip.
  • Cathode 2 (C2): Connected to the Green InGaN chip.
  • The device likely has a common anode configuration, though the exact pinout should be verified from the package diagram.
• Suggested Soldering Pad Layout: A recommended footprint for the Printed Circuit Board (PCB) is provided to ensure proper solder joint formation and mechanical stability.
• Polarity Identification: Markings on the package body (such as a notch, dot, or beveled edge) indicate pin 1 or cathode orientation. Correct placement is crucial for proper operation.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A suggested infrared (IR) reflow profile is provided for lead-free (Pb-free) solder processes. Key parameters include:

• Pre-heat Zone: Temperature range of 150–200°C.
• Pre-heat Time: Maximum of 120 seconds to gradually heat the board and components, activating the flux and minimizing thermal shock.
• Peak Temperature: Maximum of 260°C. The component body must not exceed this temperature.
• Time Above Liquidus: The time within which the solder is molten must be controlled; a typical target is 10 seconds maximum at peak temperature.
• Maximum Reflow Cycles: The device can withstand a maximum of two reflow cycles under these conditions.

The profile is based on JEDEC standards to ensure reliability. However, the optimal profile depends on the specific PCB design, solder paste, and oven, so characterization is recommended.

6.2 Hand Soldering

If hand soldering is necessary:

• Soldering Iron Temperature: Maximum 300°C.
• Soldering Time: Maximum 3 seconds per joint.
• Limit: Hand soldering should be performed only once to avoid thermal damage to the plastic package and the wire bonds inside.

6.3 Cleaning

If cleaning after soldering is required:

• Recommended Solvents: Use only alcohol-based cleaners such as ethyl alcohol or isopropyl alcohol (IPA).
• Process: Immerse the LED at normal room temperature for less than one minute. Agitation should be gentle.
• Warning: Do not use unspecified chemical liquids, as they may damage the plastic lens or package material, causing cracking or clouding.

7. Storage and Handling

7.1 Storage Conditions

• Sealed Moisture Barrier Bag (Original Packaging): Store at ≤30°C and ≤90% Relative Humidity (RH). The shelf life is one year when stored in the original bag with desiccant.
• After Bag is Opened: The components are moisture-sensitive (MSL). Store at ≤30°C and ≤60% RH. It is recommended to complete IR reflow soldering within one week of opening the bag.
• Extended Storage (Out of Bag): For storage longer than one week outside the original packaging, store in a sealed container with desiccant or in a nitrogen desiccator.
• Baking: If components have been exposed to ambient humidity for more than a week, they must be baked at approximately 60°C for at least 20 hours before soldering to remove absorbed moisture and prevent \"popcorning\" (package cracking) during reflow.

7.2 Electrostatic Discharge (ESD) Precautions

LEDs are sensitive to electrostatic discharge and voltage surges, which can degrade or destroy the semiconductor junction.

• Always handle components in an ESD-protected area.
• Use a grounded wrist strap or anti-static gloves.
• Ensure all equipment, tools, and work surfaces are properly grounded.

8. Packaging and Reel Specifications

The component is supplied in a tape-and-reel format suitable for automated assembly machines.

• Tape Width: 8 mm.
• Reel Diameter: 7 inches (178 mm).
• Quantity per Reel: 3000 pieces.
• Minimum Order Quantity (MOQ): 500 pieces for remainder quantities.
• Cover Tape: Empty component pockets are sealed with a top cover tape.
• Missing Lamps: The maximum number of consecutive missing components in the tape is two, as per standard quality specifications.
• The packaging conforms to ANSI/EIA-481 specifications.

9. Application Notes and Design Considerations

9.1 Typical Application Scenarios

• Status Indicators: Dual-color capability allows for multiple statuses (e.g., Green=OK/On, Red=Error/Alert) from a single component footprint.
• Side-Illumination/Edge-Lighting: The side-looking emission is perfect for lighting the edge of panels, light guides, or displays where front-facing LEDs are not suitable.
• Consumer Electronics: Used in appliances, audio equipment, and gadgets for power, mode, or connectivity indicators.
• Automotive Interior Lighting: For dashboard or console backlighting (subject to qualification for specific automotive grades).
• Decorative Lighting: In compact fixtures where mixed or selectable color output is desired.

9.2 Circuit Design Considerations

• Current Limiting: LEDs are current-driven devices. Always use a series current-limiting resistor or a constant-current driver for each color channel. Calculate the resistor value using Ohm's Law: R = (V_supply - V_F) / I_F. Remember that V_F is different for Green (~3.5V) and Red (~2.0V).
• Independent Control: To control the two colors independently, they must be driven by separate circuits (e.g., two microcontroller GPIO pins with their own current-limiting resistors).
• Power Dissipation: Ensure the calculated power (P = V_F * I_F) for each chip does not exceed the absolute maximum rating, considering the ambient temperature. Adequate PCB copper area may be needed for heat dissipation if operating near maximum ratings.
• Reverse Voltage Protection: As the device is not designed for reverse bias, ensure the circuit prevents any reverse voltage from being applied across the LED, especially in AC or poorly regulated DC environments. A diode in parallel (reverse polarity) can provide protection.

10. Reliability and Cautions

• Application Scope: This LED is intended for standard commercial and industrial electronic equipment. It is not specifically qualified for applications where failure could directly jeopardize life or health (e.g., aviation control, medical life-support, critical safety systems) without prior consultation and additional qualification.
• Thermal Management: Operating at high ambient temperatures or at high forward currents will reduce luminous output and shorten the device's lifetime. Derating curves (not provided in this excerpt) should be consulted for high-temperature operation.
• Long-Term Lumen Maintenance: Like all LEDs, the luminous output will gradually decrease over thousands of hours of operation. The rate of degradation depends on operating current and junction temperature.

11. Technical Comparison and Trends

11.1 Material Technology

The use of InGaN for green and AlInGaP for red represents standard, mature semiconductor technologies for these colors. InGaN-based LEDs generally offer higher efficiency and better performance at higher currents and temperatures compared to older technologies. The side-looking package style is a well-established form factor for specific lighting tasks where PCB real estate is limited on the top surface.

11.2 Industry Trends

The push for miniaturization continues to drive demand for multi-chip SMD packages like this one. Furthermore, there is a constant trend towards higher luminous efficacy (more light output per watt of electrical input) across all LED colors. While this datasheet represents a specific product, newer generations may offer higher typical intensities or improved color consistency within bins. The compatibility with automated, lead-free assembly processes remains a critical requirement for global electronics manufacturing.