LTST-S327TBJRKT SMD LED Datasheet - Dual Color (Blue/Red) - 20mA/25mA - English Technical Document

1. Product Overview

This document details the specifications for a compact, surface-mount dual-color LED component. The device integrates two distinct light-emitting chips within a single package: one producing blue light using InGaN technology, and the other producing red light using AlInGaP technology. This configuration is designed for space-constrained applications requiring multiple indication colors from a single component footprint.

1.1 Features

• Compliant with RoHS environmental directives.
• Side-viewing package design with tin-plated terminations for enhanced solderability.
• Utilizes high-efficiency InGaN (Blue) and AlInGaP (Red) semiconductor chips.
• Supplied on 8mm tape mounted on 7-inch diameter reels for automated assembly.
• Package conforms to EIA (Electronic Industries Alliance) standard outlines.
• Designed for compatibility with integrated circuits (I.C. compatible).
• Suitable for use with automated pick-and-place assembly equipment.
• Withstands standard infrared (IR) reflow soldering processes.

1.2 Applications

This component is suitable for a broad range of electronic equipment where compact, reliable status indication or backlighting is required. Typical application areas include:

• Telecommunication devices (e.g., cordless/cellular phones).
• Office automation equipment and network systems.
• Home appliances and consumer electronics.
• Industrial control and instrumentation panels.
• Keypad or keyboard backlighting.
• Status and power indicators.
• Micro-displays and icon illumination.
• Signal and symbolic luminaries.

2. Package Dimensions and Configuration

The component is housed in a standard surface-mount device (SMD) package. The lens is water clear to allow the true chip color to be visible. The pin assignment is as follows: Pin A1 is the anode for the Blue (InGaN) chip, and Pin A2 is the anode for the Red (AlInGaP) chip. The cathodes are common. All dimensional tolerances are \u00b10.1 mm unless otherwise specified on the detailed mechanical drawing (referenced in the original datasheet).

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\u00b0C.

• Power Dissipation: Blue: 76 mW, Red: 62.5 mW.
• Peak Forward Current (1/10 duty cycle, 0.1ms pulse): Blue: 100 mA, Red: 60 mA.
• Continuous DC Forward Current (IF): Blue: 20 mA, Red: 25 mA.
• Operating Temperature Range: -30\u00b0C to +85\u00b0C.
• Storage Temperature Range: -40\u00b0C to +85\u00b0C.
• Infrared Reflow Soldering: Withstand 260\u00b0C peak temperature for 10 seconds.

3.2 Electrical and Optical Characteristics

Typical performance parameters measured at Ta=25\u00b0C and IF=20mA, unless noted.

• Luminous Intensity (IV):
  • Blue: Minimum 28.0 mcd, Typical -, Maximum 180.0 mcd.
  • Red: Minimum 18.0 mcd, Typical -, Maximum 112.0 mcd.
  • Measured with a filter approximating the CIE photopic eye response.
• Viewing Angle (2\u03b8\u00bd): Approximately 130 degrees for both colors. This is the full angle where intensity drops to half its axial value.
• Peak Wavelength (\u03bbP): Blue: 468 nm (Typical), Red: 639 nm (Typical).
• Dominant Wavelength (\u03bbd):
  • Blue: Min 465 nm, Max 475 nm.
  • Red: Min 624 nm, Max 638 nm.
• Spectral Bandwidth (\u0394\u03bb): Blue: 15 nm (Typical), Red: 20 nm (Typical).
• Forward Voltage (VF) @ IF=20mA:
  • Blue: Minimum 2.8V, Maximum 3.8V.
  • Red: Minimum 1.6V, Maximum 2.4V.
• Reverse Current (IR) @ VR=5V: Maximum 10 \u00b5A for both colors. Note: The device is not designed for operation under reverse bias; this parameter is for test purposes only.

3.3 Important Notes on Characteristics

• Luminous intensity and dominant wavelength are key parameters for color consistency and brightness.
• The device is sensitive to Electrostatic Discharge (ESD). Proper ESD controls (wrist straps, grounded equipment) must be used during handling.
• Applying reverse voltage is not a normal operating condition and should be avoided in circuit design.

4. Binning System

To ensure consistency in brightness, the LEDs are sorted (binned) based on their luminous intensity at 20mA. Each bin has a defined minimum and maximum value with a tolerance of \u00b115% within the bin.

4.1 Luminous Intensity Bins

Blue Chip (mcd @ 20mA):

• Bin N: 28.0 \u2013 45.0
• Bin P: 45.0 \u2013 71.0
• Bin Q: 71.0 \u2013 112.0
• Bin R: 112.0 \u2013 180.0

Red Chip (mcd @ 20mA):

• Bin M: 18.0 \u2013 28.0
• Bin N: 28.0 \u2013 45.0
• Bin P: 45.0 \u2013 71.0
• Bin Q: 71.0 \u2013 112.0

This binning allows designers to select components that meet specific brightness requirements for their application, ensuring visual consistency in production.

5. Performance Curves Analysis

The datasheet includes typical characteristic curves which are essential for design analysis. These curves graphically represent the relationship between key parameters, providing insight beyond the tabulated minimum/typical/maximum values.

• Forward Current vs. Forward Voltage (I-V Curve): This curve shows the exponential relationship for both the blue and red chips. It is crucial for designing the current-limiting circuitry. The different turn-on voltages (lower for Red, higher for Blue) must be considered if driving the chips from a common voltage source with separate current-limiting resistors.
• Luminous Intensity vs. Forward Current: Shows how light output increases with current. It is generally linear within the recommended operating range but will saturate at higher currents. Operating near the absolute maximum current is not advised for efficiency and longevity.
• Luminous Intensity vs. Ambient Temperature: Demonstrates the thermal derating of light output. Both LED types will see a reduction in luminous intensity as ambient temperature rises. This is particularly important for designs where the LED may be subjected to high ambient temperatures or where it is driven at high currents generating significant internal heat.
• Spectral Distribution: Illustrates the relative radiant power versus wavelength for each chip, showing the peak wavelength and spectral bandwidth.

6. Mechanical, Assembly, and Handling

6.1 Package and PCB Layout

The datasheet provides detailed mechanical drawings of the component, including top, side, and bottom views with critical dimensions. A recommended printed circuit board (PCB) land pattern (pad layout) is also provided to ensure proper solder joint formation and mechanical stability during and after the reflow process. Adhering to this recommended footprint is critical for reliable assembly.

6.2 Soldering Guidelines

The component is compatible with infrared (IR) reflow soldering processes, which is the standard for SMD assembly. A suggested reflow temperature profile is provided, conforming to JEDEC standards for Pb-free (lead-free) soldering. Key parameters of this profile include:

• Preheat: 150\u00b0C to 200\u00b0C.
• Time Above Liquidus (TAL): Recommended to be within standard process windows.
• Peak Temperature: Maximum of 260\u00b0C.
• Time at Peak: Maximum of 10 seconds.
• The device should not be subjected to more than two reflow cycles.
• For manual rework with a soldering iron, the tip temperature should not exceed 300\u00b0C, and contact time should be limited to 3 seconds per joint.

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. Unspecified or aggressive chemicals may damage the package material or lens.

6.4 Storage and Moisture Sensitivity

The LEDs are packaged in a moisture-barrier bag with desiccant to prevent moisture absorption, which can cause "popcorning" (package cracking) during reflow. The Moisture Sensitivity Level (MSL) is rated at Level 3.

• Sealed Bag: Store at \u2264 30\u00b0C and \u2264 90% Relative Humidity (RH). Shelf life is one year from the bag seal date.
• After Opening: The storage environment should not exceed 30\u00b0C / 60% RH. Components should be used within one week. If stored longer out of the original bag, they must be baked at approximately 60\u00b0C for at least 20 hours before soldering to remove absorbed moisture.

7. Packaging for Production

The components are supplied on embossed carrier tape for automated assembly. The tape width is 8mm. The tape is wound onto a standard 7-inch (178mm) diameter reel. Each reel contains 3000 pieces. Detailed dimensions for the tape pockets, cover tape, and reel are provided to ensure compatibility with automated placement equipment feeders. The packing specification follows ANSI/EIA-481 standards.

8. Application Considerations and Cautions

8.1 Design Considerations

• Current Limiting: LEDs are current-driven devices. An external current-limiting resistor must be used in series with each chip (Blue and Red) when connected to a voltage source. The resistor value is calculated using Ohm's Law: R = (V_supply - V_F) / I_F, where V_F is the forward voltage of the LED at the desired current I_F. Use the maximum V_F from the datasheet to ensure the current does not exceed the limit under all conditions.
• Thermal Management: While power dissipation is low, ensuring adequate PCB copper area around the thermal pads (if any) or general trace width helps dissipate heat, maintaining LED performance and longevity, especially at higher ambient temperatures.
• ESD Protection: Incorporate ESD protection diodes on sensitive signal lines connected to the LED anodes if they are routed to connectors or user-accessible areas.

8.2 Typical Circuit Configuration

A common cathode configuration is used. To independently control the Blue and Red LEDs:

• Connect the common cathode (C) to ground.
• Connect the Blue anode (A1) to the positive supply through a current-limiting resistor (R_Blue).
• Connect the Red anode (A2) to the positive supply through a separate current-limiting resistor (R_Red).
• R_Blue and R_Red will have different values due to the different V_F of the chips for the same desired current.
• Each anode can then be driven by a microcontroller GPIO pin or a switching transistor.

8.3 Reliability and Usage Scope

The component is designed for use in standard commercial and industrial electronic equipment. For applications requiring exceptional reliability where failure could risk safety (e.g., aviation, medical life-support, transportation control), additional qualification and consultation with the component manufacturer are mandatory. The specifications in this datasheet are guaranteed under the stated test conditions. Performance in the final application depends on proper circuit design, PCB layout, and adherence to handling and assembly guidelines.