Dual Color SMD LED LTST-C235TBJRKT Datasheet - Package Dimensions - Blue 3.3V / Red 2.0V - English Technical Document

1. Product Overview

This document provides the complete technical specifications for a dual-color, surface-mount device (SMD) LED. The component integrates two distinct semiconductor chips within a single package: one emitting blue light using InGaN (Indium Gallium Nitride) technology and the other emitting red light using AlInGaP (Aluminium Indium Gallium Phosphide) technology. This design allows for compact, multi-color indication or lighting solutions in a standard EIA-compatible footprint.

The LED is packaged on 8mm tape wound onto 7-inch diameter reels, making it fully compatible with high-speed automated pick-and-place assembly equipment used in modern electronics manufacturing. It is classified as a green product and complies with RoHS (Restriction of Hazardous Substances) directives. The device is also designed to be compatible with infrared (IR) reflow soldering processes, which is the standard for assembling surface-mount components onto printed circuit boards (PCBs).

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 should not be exceeded under any operating conditions.

• Power Dissipation: Blue Chip: 76 mW, Red Chip: 75 mW.
• Peak Forward Current: Measured at a 1/10 duty cycle with a 0.1ms pulse width. Blue Chip: 100 mA, Red Chip: 80 mA.
• DC Forward Current: The maximum continuous forward current. Blue Chip: 20 mA, Red Chip: 30 mA.
• Operating Temperature Range: -20°C to +80°C.
• Storage Temperature Range: -30°C to +100°C.
• Infrared Soldering Condition: The device can withstand a peak temperature of 260°C for a maximum of 10 seconds during reflow soldering.

Operating the LED near or beyond these limits can significantly reduce its lifespan and reliability. Designers must ensure the driving circuitry maintains conditions within these specified ranges.

3. Electrical and Optical Characteristics

These characteristics are measured at Ta=25°C under standard test conditions and represent the typical performance of the device.

3.1 Luminous Intensity and Viewing Angle

Luminous intensity (Iv) is a measure of the perceived power of light emitted in a particular direction. It is measured in millicandelas (mcd).

• Blue Chip (InGaN): Typical luminous intensity is 45.0 mcd at a forward current (IF) of 20 mA, with a minimum specified value of 28.0 mcd.
• Red Chip (AlInGaP): Typical luminous intensity is 45.0 mcd at IF=20 mA, with a minimum specified value of 18.0 mcd.

The viewing angle (2θ1/2) is 130 degrees for both colors. This is the full angle at which the luminous intensity drops to half of its value at the central axis (0 degrees). A 130-degree angle indicates a wide viewing pattern, suitable for applications requiring broad visibility.

3.2 Spectral Characteristics

Spectral properties define the color quality of the emitted light.

• Peak Wavelength (λP): The wavelength at which the emission spectrum is strongest. Blue: 468 nm (Typical), Red: 639 nm (Typical).
• Dominant Wavelength (λd): The single wavelength perceived by the human eye that best represents the color. This is derived from the CIE chromaticity diagram. Blue: 470 nm (Typical), Red: 631 nm (Typical).
• Spectral Line Half-Width (Δλ): The width of the emission spectrum at half its maximum intensity. Blue: 25 nm (Typical), Red: 20 nm (Typical). A narrower half-width indicates a more saturated, pure color.

3.3 Electrical Parameters

• Forward Voltage (VF): The voltage drop across the LED when operating at the specified current.
  • Blue Chip: Typical 3.3V, Maximum 3.8V at IF=20 mA.
  • Red Chip: Typical 2.0V, Maximum 2.4V at IF=20 mA.
• Reverse Current (IR): The maximum leakage current when a reverse voltage (VR) of 5V is applied. Both chips have a maximum reverse current of 10 μA. Important Note: This parameter is for test purposes only; the LED is not designed for operation under reverse bias.

ESD Caution: LEDs are sensitive to electrostatic discharge (ESD). Proper ESD precautions, such as using grounded wrist straps, anti-static mats, and handling equipment, are mandatory to prevent damage during assembly and handling.

4. Binning System

To account for natural variations in the manufacturing process, LEDs are sorted into performance bins. This ensures consistency within a production lot.

4.1 Luminous Intensity Binning

The luminous intensity for each color is binned according to the following codes. Tolerance within each bin is +/-15%.

Blue Chip Binning (mcd @20mA):

• Code N: 28.0 – 45.0 mcd
• Code P: 45.0 – 71.0 mcd
• Code Q: 71.0 – 112.0 mcd
• Code R: 112.0 – 180.0 mcd

Red Chip Binning (mcd @20mA):

• Code M: 18.0 – 28.0 mcd
• Code N: 28.0 – 45.0 mcd
• Code P: 45.0 – 71.0 mcd
• Code Q: 71.0 – 112.0 mcd

Specifying the bin code during ordering allows designers to select LEDs with the desired brightness level for their application, ensuring visual consistency across multiple units.

5. Soldering and Assembly Guidelines

5.1 Reflow Soldering Profile

The device is designed for lead-free (Pb-free) soldering processes. A suggested infrared (IR) reflow profile is provided, compliant with JEDEC standards. Key parameters include:

• Pre-heat: 150°C to 200°C.
• Pre-heat Time: Maximum 120 seconds.
• Peak Temperature: Maximum 260°C.
• Time Above Liquidus: 10 seconds maximum (recommended for a maximum of two reflow cycles).

The exact profile must be characterized for the specific PCB design, solder paste, and oven used. The profile on page 3 of the datasheet serves as a generic target.

5.2 Hand Soldering

If hand soldering is necessary, extreme care must be taken:

• Soldering Iron Temperature: Maximum 300°C.
• Soldering Time: Maximum 3 seconds per joint.
• Hand soldering should be limited to one-time repair only, not for mass production.

5.3 Cleaning

Only specified cleaning agents should be used. Unspecified chemicals may damage the LED package.

• Recommended Solvents: Ethyl alcohol or isopropyl alcohol.
• Procedure: Immerse the LED at normal temperature for less than one minute if cleaning is necessary.

6. Mechanical and Packaging Information

6.1 Package Dimensions and Pin Assignment

The LED comes in a standard SMD package. The lens is water clear. The pin assignment is as follows:

• Pins 1, 2: Anode and Cathode for the Blue (InGaN) chip.
• Pins 3, 4: Anode and Cathode for the Red (AlInGaP) chip.

Detailed mechanical drawings are provided in the datasheet, showing all critical dimensions in millimeters. The tolerance for most dimensions is ±0.10 mm unless otherwise noted. A suggested soldering pad layout for the PCB is also included to ensure reliable solder joint formation and proper alignment during reflow.

6.2 Tape and Reel Packaging

The LEDs are supplied in industry-standard embossed carrier tape.

• Reel Size: 7 inches in diameter.
• Quantity per Reel: 3000 pieces.
• Minimum Packing Quantity: 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 lamps in the tape is two.

This packaging conforms to ANSI/EIA 481-1-A-1994 specifications, ensuring compatibility with automated assembly equipment.

7. Storage and Handling

7.1 Storage Conditions

• Sealed Package (with desiccant): Store at ≤30°C and ≤90% Relative Humidity (RH). Use within one year.
• Opened Package: Storage ambient must not exceed 30°C and 60% RH. For extended storage outside the original bag, store in a sealed container with desiccant or in a nitrogen desiccator.

7.2 Baking Requirements

If LEDs have been stored out of their original moisture-proof packaging for more than one week, they must be baked before soldering to remove absorbed moisture and prevent "popcorning" during reflow.

• Baking Condition: Approximately 60°C for at least 20 hours.
• Reflow After Opening: It is recommended to complete IR reflow soldering within one week of opening the original packaging.

8. Application Notes and Cautions

8.1 Intended Use

This LED is designed for ordinary electronic equipment applications, including office equipment, communication devices, and household appliances. It is not intended for safety-critical applications where failure could jeopardize life or health (e.g., aviation, medical life-support, transportation safety systems) without prior consultation and specific qualification.

8.2 Design Considerations

• Current Limiting: Always use a series current-limiting resistor or a constant-current driver to ensure the forward current (IF) does not exceed the maximum DC rating (20mA for Blue, 30mA for Red).
• Thermal Management: While power dissipation is low, ensuring adequate PCB copper area or thermal vias can help maintain lower junction temperatures, especially in high ambient temperature environments, thereby preserving luminous output and longevity.
• Reverse Voltage Protection: As the device is not designed for reverse operation, circuit designs should prevent the application of any reverse bias across the LED terminals.
• Driving Dual Colors: The two chips are electrically independent. They can be driven separately or together using appropriate circuitry. When driving both simultaneously, ensure the total power dissipation for the package is considered.

9. Typical Application Scenarios

The dual-color capability of this LED makes it versatile for various indication and status display functions.

• Status Indicators: Used in consumer electronics, network equipment, and industrial controls to show different operational states (e.g., power on/standby, network activity, fault conditions).
• Bi-color Displays: Can be used in simple segmented displays or as backlighting for buttons where two colors are needed.
• Automotive Interior Lighting: For non-critical interior ambiance lighting, though specific automotive-grade qualification would be required.
• Appliance User Interfaces: Providing clear, multi-state feedback on washing machines, ovens, or audio equipment.

10. Performance Analysis and Curves

The datasheet includes typical performance curves which are essential for in-depth design analysis. While the specific graphs are not reproduced in text, they typically illustrate the following relationships:

• Forward Current vs. Forward Voltage (I-V Curve): Shows the non-linear relationship, crucial for calculating the required driving voltage and series resistor value.
• Luminous Intensity vs. Forward Current: Demonstrates how light output increases with current, helping to optimize for brightness versus power consumption.
• Luminous Intensity vs. Ambient Temperature: Shows the derating of light output as temperature increases, which is critical for designs operating in elevated temperature environments.
• Spectral Distribution: Graphs depicting the relative intensity across wavelengths, confirming the peak and dominant wavelength values and the spectral purity.

Designers should refer to these curves to predict device behavior under non-standard conditions (different currents or temperatures) and to ensure robust performance across the intended operating range.