SMD LED LTST-C230KGKT Datasheet - AlInGaP Green - 20mA - 2.4V - English Technical Document

1. Product Overview

This document provides the complete technical specifications for a surface-mount device (SMD) light-emitting diode (LED). The product is a reverse-mount type chip LED utilizing Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor technology to produce green light. It is designed for automated assembly processes and is compatible with infrared reflow soldering, making it suitable for high-volume manufacturing. The device is packaged on 8mm tape wound onto 7-inch diameter reels for efficient pick-and-place operations.

1.1 Core Advantages

• High Brightness: The AlInGaP chip provides high luminous intensity.
• Design Compatibility: Features an EIA standard package footprint.
• Manufacturing Friendly: Compatible with automatic placement equipment and infrared reflow solder processes.
• Environmental Compliance: The product meets RoHS (Restriction of Hazardous Substances) directives.

2. Technical Parameter Deep-Dive

2.1 Absolute Maximum Ratings

The following ratings define the limits beyond which permanent damage to the device may occur. All values are specified at an ambient temperature (Ta) of 25°C.

• Power Dissipation (Pd): 75 mW
• Peak Forward Current (IFP): 80 mA (at 1/10 duty cycle, 0.1ms pulse width)
• DC Forward Current (IF): 30 mA
• Reverse Voltage (VR): 5 V
• Operating Temperature Range (Topr): -30°C to +85°C
• Storage Temperature Range (Tstg): -40°C to +85°C
• Infrared Soldering Condition: 260°C peak temperature for a maximum of 10 seconds.

2.2 Electro-Optical Characteristics

These parameters define the device's performance under normal operating conditions, typically measured at Ta=25°C and a forward current (IF) of 20mA, unless otherwise noted.

• Luminous Intensity (Iv): 18.0 mcd (Minimum), 35.0 mcd (Typical). Measured with a sensor/filter approximating the CIE photopic eye-response curve.
• Viewing Angle (2θ1/2): 130 degrees. This is the full angle at which luminous intensity is half the value measured on the central axis.
• Peak Emission Wavelength (λP): 574 nm.
• Dominant Wavelength (λd): 571 nm. This is the single wavelength derived from the CIE chromaticity diagram that best represents the perceived color.
• Spectral Line Half-Width (Δλ): 15 nm. This indicates the spectral purity of the emitted light.
• Forward Voltage (VF): 2.0 V (Minimum), 2.4 V (Typical) at IF=20mA.
• Reverse Current (IR): 10 μA (Maximum) at VR=5V.

3. Binning System Explanation

The devices are sorted into bins based on key parameters to ensure consistency in application. The bin codes for this product are defined as follows:

3.1 Forward Voltage Binning

Binned at IF=20mA. Tolerance on each bin is ±0.1V.
Bin Code 4: 1.90V - 2.00V
Bin Code 5: 2.00V - 2.10V
Bin Code 6: 2.10V - 2.20V
Bin Code 7: 2.20V - 2.30V
Bin Code 8: 2.30V - 2.40V

3.2 Luminous Intensity Binning

Binned at IF=20mA. Tolerance on each bin is ±15%.
Bin Code M: 18.0 mcd - 28.0 mcd
Bin Code N: 28.0 mcd - 45.0 mcd
Bin Code P: 45.0 mcd - 71.0 mcd

3.3 Dominant Wavelength Binning

Binned at IF=20mA. Tolerance for each bin is ±1nm.
Bin Code C: 567.5 nm - 570.5 nm
Bin Code D: 570.5 nm - 573.5 nm
Bin Code E: 573.5 nm - 576.5 nm

4. Performance Curve Analysis

The datasheet references typical performance curves which are essential for design. While the specific graphs are not reproduced in text, they typically include:

• Relative Luminous Intensity vs. Forward Current: Shows how light output increases with current, important for driving circuit design.
• Forward Voltage vs. Forward Current: The IV characteristic curve, crucial for calculating power dissipation and selecting current-limiting resistors.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the thermal derating of light output, which is critical for applications in varying environmental conditions.
• Spectral Distribution: A plot of relative intensity versus wavelength, showing the peak at 574nm and the 15nm half-width.

5. Mechanical and Package Information

5.1 Package Dimensions

The device conforms to an EIA standard package outline. All dimensions are in millimeters with a general tolerance of ±0.10mm unless otherwise specified. The datasheet includes a detailed dimensional drawing showing the length, width, height, and lead positions for the reverse-mount configuration.

5.2 Polarity Identification

As a reverse-mount component, polarity identification on the PCB is critical. The suggested soldering pad layout in the datasheet clearly indicates the cathode and anode pad geometries to ensure correct orientation during assembly.

5.3 Tape and Reel Specifications

The device is supplied on 8mm carrier tape per EIA-481 standards, wound on 7-inch (178mm) diameter reels. Each reel contains 3000 pieces. Key tape specifications include pocket dimensions, cover tape, and leader/trailer tape requirements to ensure compatibility with automated equipment.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A suggested infrared reflow profile for lead-free (Pb-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: As per the specific profile curve (referenced on page 3 of the original document).
- Critical Limit: The device should not be exposed to 260°C for more than 10 seconds. Reflow should be performed a maximum of two times.

6.2 Hand Soldering

If hand soldering is necessary:
- Iron Temperature: Maximum 300°C.
- Soldering Time: Maximum 3 seconds per joint.
- Important: Hand soldering should be performed only once.

6.3 Storage Conditions

• Sealed Package (with desiccant): Store at ≤30°C and ≤90% RH. Recommended use within one year of opening the moisture barrier bag.
• Opened Package / After Exposure: Store at ≤30°C and ≤60% RH. Components should be IR-reflowed within 672 hours (28 days) of exposure to ambient air (MSL 2a). For longer storage, use a sealed container with desiccant or a nitrogen desiccator. Components stored beyond 672 hours require baking at approximately 60°C for at least 20 hours before soldering.

6.4 Cleaning

Do not use unspecified chemicals. If cleaning is required post-soldering, immerse the LED in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute.

7. Packaging and Ordering Information

The standard ordering unit is a 7-inch reel containing 3000 pieces. A minimum packing quantity of 500 pieces applies for remainder quantities. The tape and reel packaging ensures compatibility with high-speed automated assembly lines. The part number LTST-C230KGKT encodes the specific characteristics of this device.

8. Application Recommendations

8.1 Typical Application Scenarios

This LED is suitable for a wide range of applications requiring a compact, bright green indicator, including but not limited to:
- Status indicators on consumer electronics (e.g., routers, chargers, appliances).
- Backlighting for membrane switches or small panels.
- Decorative lighting in compact spaces.
- Industrial control panel indicators.

8.2 Design Considerations

• Current Limiting: Always use a series resistor or constant current driver to limit the forward current to a maximum of 30mA DC. The typical operating point is 20mA.
• Thermal Management: Ensure the PCB design allows for heat dissipation, especially if operating near maximum current or in high ambient temperatures, as luminous intensity decreases with rising temperature.
• ESD Protection: LEDs are sensitive to electrostatic discharge (ESD). Implement proper ESD controls during handling and assembly, such as using grounded wrist straps and workstations.
• Reverse Voltage Protection: The maximum reverse voltage is only 5V. Incorporate protection (e.g., a diode in parallel) if the circuit exposes the LED to potential reverse bias.

9. Technical Comparison and Differentiation

The key differentiating factors of this LED are its reverse-mount design and AlInGaP technology. Reverse-mount allows for a lower profile assembly as the LED is mounted on the opposite side of the PCB from the viewing direction. AlInGaP technology offers higher efficiency and better performance stability compared to older technologies like standard GaP for green LEDs, resulting in higher brightness and more consistent color.

10. Frequently Asked Questions (FAQ)

Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λP) is the wavelength at which the emission spectrum has its maximum intensity (574nm). Dominant wavelength (λd) is a calculated value (571nm) from the CIE color chart that best represents the color perceived by the human eye.

Q: Can I drive this LED with a 3.3V supply?
A: Yes, but you must use a current-limiting resistor. For example, with a VF of 2.4V at 20mA, the resistor value would be R = (3.3V - 2.4V) / 0.02A = 45 Ohms. Use the nearest standard value and check power rating.

Q: What does \"MSL 2a\" mean for storage?
A: Moisture Sensitivity Level 2a indicates the component can be exposed to factory floor conditions (≤60% RH, ≤30°C) for up to 4 weeks (672 hours) before it requires baking prior to reflow soldering to prevent \"popcorning\" damage.

11. Practical Design Case Study

Scenario: Designing a status indicator for a portable device powered by a 5V USB source. The indicator needs to be bright green and mounted on the bottom side of the PCB, visible through a small window.

Solution: The LTST-C230KGKT is ideal due to its reverse-mount capability. A simple series resistor circuit is designed: R = (5V - 2.4V) / 0.02A = 130 Ohms. A 130Ω, 1/8W resistor is selected. The PCB layout uses the suggested pad dimensions from the datasheet. The LED is placed on the bottom layer, and the viewing window in the enclosure is aligned with its position. The 130-degree viewing angle ensures good visibility.

12. Technology Principle Introduction

This LED is based on Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor material. When a forward voltage is applied across the p-n junction, electrons and holes recombine in the active region, releasing energy in the form of photons (light). The specific ratio of aluminum, indium, and gallium in the crystal lattice determines the bandgap energy, which directly corresponds to the wavelength (color) of the emitted light—in this case, green (~571nm). The \"water clear\" lens is made of epoxy or silicone that does not contain a diffusant, allowing the intrinsic bright, saturated color of the chip to be seen.

13. Industry Trends

The trend in SMD indicator LEDs continues towards higher efficiency (more light output per mA), improved color consistency through tighter binning, and enhanced reliability under higher temperature soldering processes like lead-free reflow. There is also a drive for miniaturization while maintaining or increasing optical performance. Reverse-mount and side-view packages are increasingly popular for achieving sleek, low-profile designs in modern consumer electronics. Furthermore, integration with drive electronics (e.g., built-in ICs for constant current or color control) is a growing area, though this particular device remains a discrete, standard component.