LTST-C193KGKT-5A SMD LED Datasheet - Dimensions 1.6x0.8x0.35mm - Voltage 1.7-2.3V - Green AlInGaP - English Technical Document

1. Product Overview

This document details the specifications for a miniature, surface-mount LED lamp designed for automated printed circuit board (PCB) assembly. The device is characterized by its exceptionally low profile, making it suitable for space-constrained applications. It utilizes an AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material to produce green light, offering high brightness in a compact form factor.

1.1 Features

• Compliant with RoHS (Restriction of Hazardous Substances) directives.
• Extremely thin package profile of 0.35 millimeters.
• High-brightness output using AlInGaP chip technology.
• Packaged on 8mm tape wound onto 7-inch diameter reels for automated pick-and-place.
• Standard EIA (Electronic Industries Alliance) package outline.
• Compatible with standard integrated circuit (IC) drive levels.
• Designed for compatibility with automatic placement equipment.
• Suitable for infrared (IR) reflow soldering processes.

1.2 Applications

This LED is intended for a broad range of electronic equipment where compact size and reliable indication are required. Typical application areas include:

• Telecommunication devices, office automation equipment, home appliances, and industrial control systems.
• Backlighting for keypads and keyboards.
• Status and power indicators.
• Micro-displays and panel indicators.
• Signal and symbolic illumination.

2. Package Dimensions and Mechanical Data

The LED is housed in a standard surface-mount package. The lens color is water clear, while the light source emits a green color. Critical dimensions include a body length of 1.6mm, a width of 0.8mm, and a height of 0.35mm. All dimensional tolerances are typically ±0.1mm unless otherwise specified. Detailed mechanical drawings should be referenced for exact pad layout and placement.

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°C.

• Power Dissipation (Pd): 50 mW
• Peak Forward Current (IFP): 40 mA (at 1/10 duty cycle, 0.1ms pulse width)
• Continuous Forward Current (IF): 20 mA DC
• Reverse Voltage (VR): 5 V
• Operating Temperature Range (Topr): -30°C to +85°C
• Storage Temperature Range (Tstg): -40°C to +85°C
• Infrared Reflow Soldering Condition: 260°C peak temperature for a maximum of 10 seconds.

3.2 Suggested IR Reflow Profile

For lead-free (Pb-free) soldering processes, a specific temperature profile is recommended to ensure reliable solder joints without damaging the LED package. The profile typically includes a pre-heat stage, a ramp-up, a peak temperature zone not exceeding 260°C, and a controlled cooling phase. The total time above 217°C (liquidus temperature for typical lead-free solder) should be managed according to solder paste specifications.

3.3 Electrical and Optical Characteristics

These parameters define the typical performance of the LED under normal operating conditions at Ta=25°C.

• Luminous Intensity (Iv): Ranges from 4.5 to 28 millicandelas (mcd) at a forward current (IF) of 5 mA. Measured with a sensor filtered to the CIE photopic eye-response curve.
• Viewing Angle (2θ½): 130 degrees. This is the full angle at which the luminous intensity drops to half of its on-axis value.
• Peak Emission Wavelength (λP): Typically 574.0 nanometers (nm).
• Dominant Wavelength (λd): Ranges from 567.5 nm to 576.5 nm at IF=5mA. This defines the perceived color of the light.
• Spectral Line Half-Width (Δλ): Approximately 15 nm, indicating the spectral purity of the green emission.
• Forward Voltage (VF): Ranges from 1.7V to 2.3V at IF=5mA.
• Reverse Current (IR): Maximum of 10 microamperes (µA) at a reverse voltage (VR) of 5V.

4. Binning System

To ensure consistency in application, LEDs are sorted into bins based on key parameters. This allows designers to select parts that meet specific voltage, brightness, and color requirements.

4.1 Forward Voltage (VF) Binning

Bins are defined by the forward voltage drop at 5mA.
E2: 1.7V - 1.9V
E3: 1.9V - 2.1V
E4: 2.1V - 2.3V
Tolerance per bin: ±0.1V

4.2 Luminous Intensity (Iv) Binning

Bins are defined by the luminous intensity at 5mA.
J: 4.5 mcd - 7.1 mcd
K: 7.1 mcd - 11.2 mcd
L: 11.2 mcd - 18.0 mcd
M: 18.0 mcd - 28.0 mcd
Tolerance per bin: ±15%

4.3 Hue (Dominant Wavelength, λd) Binning

Bins are defined by the dominant wavelength at 5mA, determining the precise shade of green.
C: 567.5 nm - 570.5 nm
D: 570.5 nm - 573.5 nm
E: 573.5 nm - 576.5 nm
Tolerance per bin: ±1 nm

5. Typical Performance Curves

Graphical data provides deeper insight into device behavior under varying conditions. Typical curves include:

• Forward Current vs. Forward Voltage (I-V Curve): Shows the exponential relationship, critical for current-limiting resistor calculation.
• Luminous Intensity vs. Forward Current: Demonstrates how light output increases with current, up to the maximum rating.
• Luminous Intensity vs. Ambient Temperature: Shows the decrease in light output as junction temperature rises, important for thermal management.
• Spectral Distribution: A plot of relative intensity versus wavelength, centered around the peak wavelength of 574nm.

6. User Guide and Assembly Information

6.1 Cleaning

If cleaning after soldering is necessary, only use specified solvents. Immerse the LED in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute. Avoid using aggressive or unspecified chemical cleaners which may damage the epoxy lens or package.

6.2 Recommended PCB Pad Layout

A suggested land pattern (footprint) for the PCB is provided to ensure proper solder fillet formation and mechanical stability. This pattern accounts for the package dimensions and recommended solder mask clearance.

6.3 Tape and Reel Packaging Specifications

The LEDs are supplied on embossed carrier tape with a protective cover tape. Key specifications include 8mm tape width, pocket spacing, and reel dimensions (7-inch diameter). Standard reel quantity is 5000 pieces. Packaging follows ANSI/EIA-481 standards.

6.4 Storage and Handling

• ESD Precautions: The device is sensitive to electrostatic discharge (ESD). Use wrist straps, anti-static mats, and properly grounded equipment during handling.
• Moisture Sensitivity: The package is rated MSL 2a. Once the original moisture-barrier bag is opened, components should be subjected to IR reflow within 672 hours (28 days) under controlled humidity (<60% RH). For storage beyond this period or in uncontrolled environments, a bake-out at approximately 60°C for 20 hours is recommended before soldering.
• Unopened Packages: Store at ≤ 30°C and ≤ 90% relative humidity. Use within one year from the date code.

7. Application Notes and Design Considerations

7.1 Current Limiting

An external current-limiting resistor is mandatory for reliable operation. The resistor value (R) can be calculated using Ohm's Law: R = (Vsupply - VF) / IF, where VF is the forward voltage from the bin or typical value, and IF is the desired drive current (not to exceed 20mA DC). Always consider power supply tolerance and LED VF variation in the calculation.

7.2 Thermal Management

While the power dissipation is low, maintaining a low junction temperature is crucial for long-term reliability and stable light output. Ensure adequate PCB copper area around the LED pads to act as a heat sink, especially when driving at higher currents within the rated range.

7.3 Optical Design

The wide 130-degree viewing angle makes this LED suitable for applications requiring broad illumination or visibility from multiple angles. For focused light, external lenses or light guides may be necessary. The water-clear lens provides minimal light absorption.

7.4 Soldering Process Control

Adherence to the recommended reflow profile is critical. Excessive time above liquidus temperature or peak temperatures exceeding 260°C can cause internal wire bond failure or package cracking. Manual soldering with an iron should be limited to 300°C for a maximum of 3 seconds, applied only once.

8. Technical Comparison and Advantages

The primary differentiator of this component is its 0.35mm profile, which is significantly thinner than many standard SMD LEDs. This allows for integration into ultra-slim consumer electronics. The use of AlInGaP technology provides higher efficiency and better temperature stability compared to some older green LED technologies, resulting in more consistent brightness and color over the operating temperature range. The comprehensive binning system offers designers precise control over the visual and electrical characteristics of their end product.

9. Frequently Asked Questions (FAQ)

Q: Can I drive this LED directly from a 3.3V or 5V logic output?
A: No. You must always use a series current-limiting resistor. The calculation in section 7.1 applies. Driving it directly will likely exceed the maximum current and destroy the LED.

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 highest intensity. Dominant wavelength (λd) is the single wavelength that would produce the same color perception as the LED's light. λd is more relevant for color specification.

Q: How do I interpret the bin code in the part number?
A>The part number LTST-C193KGKT-5A includes embedded codes. The 'K' typically corresponds to a specific luminous intensity bin (e.g., the K bin from 7.1-11.2 mcd), and the 'G' indicates the green color. The exact mapping should be confirmed with the manufacturer's detailed bin code list.

Q: Is this LED suitable for outdoor use?
A: The operating temperature range is -30°C to +85°C, which covers many environments. However, the datasheet specifies applications as primarily indoor (e.g., signboards). For outdoor use, consider additional protection from UV radiation and moisture ingress, which are not covered in this document.

10. Operational Principle

This LED operates on the principle of electroluminescence in a semiconductor p-n junction. When a forward voltage exceeding the diode's turn-on voltage (VF) is applied, electrons from the n-type AlInGaP material recombine with holes from the p-type material in the active region. This recombination event releases energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy, which directly defines the wavelength (color) of the emitted light, in this case, green. The epoxy lens serves to protect the semiconductor chip, shape the light output beam, and enhance light extraction from the material.