Dual Color SMD LED LTST-C295KGKSKT Datasheet - Package Dimensions - Green/Yellow - 20mA - English Technical Document

1. Product Overview

This document details the specifications for a dual-color, surface-mount LED. The device integrates two distinct AlInGaP semiconductor chips within a single, ultra-thin package, enabling the emission of green and yellow light. It is designed for compatibility with automated assembly processes and modern lead-free soldering techniques, making it suitable for high-volume manufacturing.

The core advantages of this component include its compact form factor, high luminous intensity output from advanced AlInGaP technology, and compliance with environmental regulations. It is targeted at applications in consumer electronics, industrial indicators, automotive interior lighting, and general-purpose signaling where reliable, dual-color indication in a minimal footprint is required.

2. Technical Specifications Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed. For both the green and yellow chips:

• Power Dissipation (Pd): 75 mW. This is the maximum power the LED can dissipate as heat.
• Peak Forward Current (I_FP): 80 mA. This is permissible only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width) to prevent overheating.
• Continuous Forward Current (I_F): 30 mA DC. This is the recommended maximum current for continuous operation.
• Reverse Voltage (V_R): 5 V. Exceeding this voltage in reverse bias can break down the semiconductor junction.
• Operating Temperature (T_opr): -30°C to +85°C. The ambient temperature range for reliable operation.
• Storage Temperature (T_stg): -40°C to +85°C.

2.2 Electro-Optical Characteristics

Measured at Ta=25°C and I_F=20mA, these parameters define the device's performance under normal operating conditions.

• Luminous Intensity (I_V): The green chip has a minimum of 18.0 mcd and a maximum of 112.0 mcd. The yellow chip has a minimum of 28.0 mcd and a maximum of 180.0 mcd. The typical values are not specified, indicating performance is defined by the binning system.
• Viewing Angle (2θ_1/2): 130 degrees (typical). This wide viewing angle makes the LED suitable for applications requiring visibility from a broad range of perspectives.
• Peak Wavelength (λ_P): 574 nm (green, typical) and 591 nm (yellow, typical). This is the wavelength at which the emitted optical power is greatest.
• Dominant Wavelength (λ_d): 571 nm (green, typical) and 589 nm (yellow, typical). This is the single wavelength perceived by the human eye, defining the color point on the CIE chromaticity diagram.
• Spectral Bandwidth (Δλ): 15 nm (typical) for both colors, indicating relatively pure color emission.
• Forward Voltage (V_F): 2.0 V (typical), 2.4 V (maximum) at 20mA. This low voltage is compatible with common logic-level power supplies.
• Reverse Current (I_R): 10 μA (maximum) at V_R=5V.

3. Binning System Explanation

To ensure color and brightness consistency in production, LEDs are sorted into bins. This device uses a luminous intensity binning system.

3.1 Green Chip Binning

Bins: M (18.0-28.0 mcd), N (28.0-45.0 mcd), P (45.0-71.0 mcd), Q (71.0-112.0 mcd). Each bin has a tolerance of +/-15%.

3.2 Yellow Chip Binning

Bins: N (28.0-45.0 mcd), P (45.0-71.0 mcd), Q (71.0-112.0 mcd), R (112.0-180.0 mcd). Each bin has a tolerance of +/-15%.

Designers must specify the required bin codes when ordering to guarantee the desired brightness levels for their application. There is no separate wavelength/color binning indicated, suggesting tight control over the dominant wavelength during manufacturing.

4. Performance Curve Analysis

While specific graphical data is referenced but not fully detailed in the provided text, typical curves for such a device would include:

• I-V (Current-Voltage) Curve: Shows the exponential relationship between forward voltage and current. The curve will have a characteristic \"knee\" voltage around 2.0V.
• Luminous Intensity vs. Forward Current: A relatively linear relationship up to the maximum rated current, after which efficiency may drop due to heating.
• Luminous Intensity vs. Ambient Temperature: Shows the decrease in light output as junction temperature rises, a critical factor for thermal management in design.
• Spectral Distribution: Graphs showing the relative optical power versus wavelength, peaking at the specified λ_P with a width defined by Δλ.

5. Mechanical and Package Information

The device features an industry-standard SMD package. Key mechanical notes include:

• The package is extra thin with a height of 0.55 mm.
• All dimensions use millimeters as the primary unit, with a general tolerance of ±0.10 mm unless otherwise specified.
• The pin assignment is: Green LED on pins 1 and 3, Yellow LED on pins 2 and 4. This common-cathode or common-anode configuration (not explicitly stated but typical for dual LEDs) allows independent control of each color.
• The lens is water clear, allowing the true chip color to be seen.
• Detailed package dimension drawings, tape dimensions, and reel specifications (7-inch diameter, 4000 pieces per reel) are provided for PCB land pattern design and automated handling.

6. Soldering and Assembly Guide

6.1 Reflow Soldering Profile

A suggested infrared reflow profile for lead-free processes is provided. Key parameters include:

• Pre-heat: 150-200°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 profile is based on JEDEC standards to ensure reliable mounting without damaging the LED package or internal wire bonds.

6.2 Hand Soldering

If necessary, hand soldering with an iron is permissible with limits:

• Iron Temperature: Maximum 300°C.
• Soldering Time: Maximum 3 seconds per joint, for one time only.

6.3 Storage and Handling

• ESD Precautions: The device is sensitive to electrostatic discharge. Use wrist straps, grounded equipment, and anti-static packaging.
• Moisture Sensitivity: When sealed in the original moisture-proof bag with desiccant, the shelf life is one year at ≤30°C/90%RH. Once opened, LEDs should be used within one week or baked (60°C for 20+ hours) before reflow if stored longer.
• Cleaning: Only use specified solvents like ethyl alcohol or isopropyl alcohol at room temperature for less than one minute. Unspecified chemicals may damage the epoxy lens.

7. Packaging and Ordering

The device is supplied in 8mm tape on 7-inch diameter reels for compatibility with automatic pick-and-place machines. The minimum order quantity for remnants is 500 pieces. The tape and reel specifications follow ANSI/EIA 481 standards.

8. Application Recommendations

8.1 Typical Application Scenarios

• Status Indicators: Dual-color capability allows for showing multiple states (e.g., green=OK, yellow=Warning) in a single component footprint.
• Backlighting: For small LCD displays or keypads requiring customizable color feedback.
• Consumer Electronics: Power buttons, charge status lights, decorative lighting in compact devices.
• Automotive Interior: Dashboard and control panel illumination where space is limited.

8.2 Design Considerations

• Current Limiting: Always use a series resistor or constant current driver to limit the forward current to 30mA DC or less per chip.
• Thermal Management: Ensure adequate PCB copper area or thermal vias to dissipate heat, especially if operating near maximum current or in high ambient temperatures, to maintain luminous output and longevity.
• PCB Land Pattern: Follow the recommended solder pad dimensions to ensure proper soldering and mechanical stability.
• Optical Design: The wide 130-degree viewing angle may require light guides or diffusers if a more focused beam is desired.

9. Technical Comparison and Differentiation

Compared to older single-color LEDs or those using different semiconductor materials (like traditional GaP), this AlInGaP-based dual-color LED offers:

• Higher Efficiency: AlInGaP technology provides higher luminous intensity per unit current (mcd/mA) for amber/yellow/green colors compared to older technologies.
• Space Savings: Integrating two colors into one 0.55mm thin package reduces PCB area and component count versus using two discrete LEDs.
• Process Compatibility: Full compatibility with infrared reflow soldering and automated placement streamlines modern SMT assembly lines.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive both the green and yellow LEDs at 30mA simultaneously?
A: The absolute maximum power dissipation is 75mW per chip. At a typical Vf of 2.0V and 30mA, each chip dissipates 60mW (P=I*V). Driving both simultaneously would dissipate 120mW in total, which exceeds the per-chip rating and requires careful thermal analysis. It is safer to operate below the absolute maximums, perhaps at 20mA as used in the test conditions.

Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λ_P) is the physical measurement of the highest point in the LED's emission spectrum. Dominant wavelength (λ_d) is a calculated value based on human color perception (CIE chart) that represents the \"color\" we see. For a monochromatic source like this LED, they are very close.

Q: How do I interpret the bin codes when designing?
A: Select the bin that guarantees your minimum required brightness. For example, if your design needs at least 50 mcd from the yellow LED, you must specify bin Q (71.0-112.0 mcd) or higher, as bin P only guarantees up to 71.0 mcd.

11. Practical Design and Usage Case

Case: Dual-State System Status Indicator
In a portable medical device, a single LED is used to indicate battery and system status. The microcontroller drives the pins independently.
- Circuit: Two GPIO pins, each connected through a 100Ω current-limiting resistor (calculated for ~20mA from a 3.3V supply: R = (3.3V - 2.0V) / 0.02A ≈ 65Ω; 100Ω provides a safety margin) to the anode of the respective LED color. The cathodes are connected to ground.
- Logic: Green = System On/Normal. Yellow = Battery Charging/Low Warning. Both off = System Off. This implementation saves space, simplifies the user interface, and is assembled using standard SMT reflow processes following the provided profile.

12. Operating Principle Introduction

This LED is based on AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material. When a forward voltage is applied across the p-n junction, electrons and holes are injected into the active region where they recombine. This recombination process releases energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy, which directly dictates the wavelength (color) of the emitted light—green at ~571nm and yellow at ~589nm in this device. The two chips are housed in a single epoxy package with a clear lens that minimizes light absorption and provides environmental protection.

13. Technology Trends

The development of LEDs continues to focus on several key areas relevant to this component: increased luminous efficacy (more light output per electrical watt), improved color consistency and saturation, further miniaturization of packages, and enhanced reliability under higher temperature and humidity conditions. The use of advanced semiconductor materials like AlInGaP for the amber-green spectrum represents a mature but optimized technology, offering a strong balance of performance, cost, and reliability for indicator applications. Future trends may involve integration of drive electronics within the package or even broader spectrum tunability.