SMD LED LTST-C190KGKT Datasheet - Dimensions 3.2x1.6x0.8mm - Voltage 1.9-2.4V - Power 75mW - Green AlInGaP - English Technical Document

1. Product Overview

This document details the specifications for a surface-mount device (SMD) LED lamp. This component is designed for automated printed circuit board (PCB) assembly and is particularly suited for applications where space is a critical constraint. The LED features an ultra-thin profile and utilizes an advanced AlInGaP semiconductor material for its light-emitting chip, delivering high brightness in the green spectrum.

1.1 Features

• Compliant with RoHS (Restriction of Hazardous Substances) directives.
• Extremely low profile with a height of only 0.80 millimeters.
• High luminous intensity provided by an AlInGaP (Aluminum Indium Gallium Phosphide) chip.
• Packaged on 8mm tape wound onto 7-inch diameter reels for automated pick-and-place systems.
• Standardized EIA (Electronic Industries Alliance) package outline.
• Compatible with standard integrated circuit (IC) drive levels.
• Designed for compatibility with automated component placement equipment.
• Suitable for infrared (IR) reflow soldering processes commonly used in surface-mount technology (SMT).

1.2 Applications

This LED is versatile and can be integrated into a wide array of electronic devices and systems, including but not limited to:

• Telecommunication equipment (e.g., cordless phones, cellular phones).
• Office automation devices and network systems.
• Home appliances and consumer electronics.
• Industrial control and instrumentation panels.
• Backlighting for keypads and keyboards.
• Status and power indicators.
• Micro-displays and symbol illumination.
• Indoor signage and informational displays.

2. Technical Specifications Deep Dive

The following sections provide a detailed analysis of the LED's electrical, optical, and environmental characteristics.

2.1 Absolute Maximum Ratings

These values represent the limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed.

• Power Dissipation (Pd): 75 mW
• Peak Forward Current (I_F(PEAK)): 80 mA (at 1/10 duty cycle, 0.1ms pulse width)
• Continuous Forward Current (I_F): 30 mA DC
• Reverse Voltage (V_R): 5 V
• Operating Temperature Range (T_opr): -30°C to +85°C
• Storage Temperature Range (T_stg): -40°C to +85°C
• Infrared Reflow Soldering Temperature: 260°C maximum for 10 seconds.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters measured at an ambient temperature (T_a) of 25°C under specified test conditions.

• Luminous Intensity (I_V): 18.0 - 71.0 mcd (measured at I_F = 20 mA).
• Viewing Angle (2θ_1/2): 130 degrees (the off-axis angle where intensity is half the on-axis value).
• Peak Emission Wavelength (λ_P): 574.0 nm (typical).
• Dominant Wavelength (λ_d): 567.5 - 576.5 nm (measured at I_F = 20 mA).
• Spectral Line Half-Width (Δλ): 15 nm (typical).
• Forward Voltage (V_F): 1.9 - 2.4 V (measured at I_F = 20 mA).
• Reverse Current (I_R): 10 μA maximum (measured at V_R = 5 V).

3. Binning System Explanation

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

3.1 Forward Voltage (V_F) Binning

Bins define the range of forward voltage drop across the LED when driven at 20mA. Tolerance on each bin is ±0.1V.

• Bin 4: 1.90V - 2.00V
• Bin 5: 2.00V - 2.10V
• Bin 6: 2.10V - 2.20V
• Bin 7: 2.20V - 2.30V
• Bin 8: 2.30V - 2.40V

3.2 Luminous Intensity (I_V) Binning

Bins categorize the minimum and maximum luminous output at 20mA. Tolerance on each bin is ±15%.

• Bin M: 18.0 mcd - 28.0 mcd
• Bin N: 28.0 mcd - 45.0 mcd
• Bin P: 45.0 mcd - 71.0 mcd

3.3 Hue / Dominant Wavelength (λ_d) Binning

This binning controls the precise shade of green. Tolerance for each bin is ±1 nm.

• Bin C: 567.5 nm - 570.5 nm
• Bin D: 570.5 nm - 573.5 nm
• Bin E: 573.5 nm - 576.5 nm

4. Performance Curve Analysis

Typical performance curves (not reproduced in text but referenced in the datasheet) provide visual insight into device behavior under varying conditions. These typically include:

• Relative Luminous Intensity vs. Forward Current: Shows how light output increases with drive current, typically in a non-linear relationship.
• Forward Voltage vs. Forward Current: Illustrates the diode's IV characteristic curve.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the thermal derating of light output; intensity generally decreases as temperature rises.
• Spectral Distribution: A graph showing the relative radiant power across wavelengths, centered around the peak wavelength of 574nm with a typical half-width of 15nm.

5. Mechanical & Packaging Information

5.1 Package Dimensions

The LED has a compact, rectangular SMD footprint. Key dimensions (in millimeters) are: length = 3.2, width = 1.6, height = 0.8. A detailed dimensional drawing specifies pad locations, component outline, and polarity marking (typically a cathode indicator). All dimensional tolerances are ±0.1mm unless otherwise noted.

5.2 Recommended PCB Land Pattern

A suggested solder pad layout is provided to ensure reliable soldering and proper alignment during the reflow process. This pattern accounts for solder fillet formation and component self-alignment during reflow.

5.3 Tape and Reel Packaging

The LEDs are supplied in embossed carrier tape with a protective cover tape. Key packaging details:

• Carrier Tape Width: 8 mm.
• Reel Diameter: 7 inches (178 mm).
• Quantity per Reel: 4000 pieces.
• Minimum Order Quantity (MOQ): 500 pieces for remainder quantities.
• The packaging conforms to ANSI/EIA-481 standards.

6. Soldering & Assembly Guidelines

6.1 IR Reflow Soldering (Pb-Free Process)

The component is rated for lead-free (Pb-free) soldering processes. A suggested reflow profile is provided, adhering to JEDEC standards. Key parameters include:

• Pre-heat Temperature: 150°C to 200°C.
• Pre-heat Time: Maximum 120 seconds.
• Peak Body Temperature: Maximum 260°C.
• Time Above 260°C: Maximum 10 seconds.
• Number of Reflow Passes: Maximum two times.

Note: The actual temperature profile must be characterized for the specific PCB design, solder paste, and oven used.

6.2 Hand Soldering

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

• Iron Temperature: Maximum 300°C.
• Soldering Time: Maximum 3 seconds per lead.
• Number of Soldering Attempts: One time only is recommended to prevent thermal damage.

6.3 Cleaning

If cleaning after soldering is required, only specified solvents should be used to avoid damaging the LED package. Recommended agents include ethyl alcohol or isopropyl alcohol (IPA). The LED should be immersed at normal temperature for less than one minute.

7. Storage & Handling Precautions

7.1 Electrostatic Discharge (ESD) Sensitivity

LEDs are sensitive to electrostatic discharge. Proper ESD controls must be in place during handling, including the use of grounded wrist straps, anti-static mats, and conductive containers. All equipment must be properly grounded.

7.2 Moisture Sensitivity

This component has a Moisture Sensitivity Level (MSL) rating. The specific level (e.g., MSL 3) indicates how long the device can be exposed to ambient room conditions after the original sealed bag is opened before it requires baking to remove absorbed moisture.

• Sealed Package: Store at ≤30°C and ≤90% Relative Humidity (RH). Shelf life is one year when stored in the original moisture-proof bag with desiccant.
• Opened Package: For components removed from the sealed bag, the storage environment should not exceed 30°C and 60% RH. It is recommended to complete the IR reflow process within one week. For longer storage outside the original bag, store in a sealed container with desiccant. Components stored for more than one week should be baked (e.g., at 60°C for 20 hours) prior to soldering to prevent \"popcorning\" during reflow.

8. Application Notes & Design Considerations

8.1 Current Limiting

An external current-limiting resistor is almost always required when driving an LED from a voltage source. The resistor value can be calculated using Ohm's Law: R = (V_source - V_F) / I_F. Using the maximum V_F from the datasheet (2.4V) ensures the resistor provides adequate current limiting even for LEDs from the highest voltage bin.

8.2 Thermal Management

While the power dissipation is low (75mW), maintaining the LED junction temperature within the specified operating range is crucial for long-term reliability and stable light output. Ensure adequate thermal relief in the PCB pad design and avoid placing the LED near other significant heat sources.

8.3 Optical Design

The wide 130-degree viewing angle makes this LED suitable for applications requiring broad, diffuse illumination rather than a focused beam. For indicator applications, consider the required luminous intensity (selecting the appropriate I_V bin) to ensure visibility under ambient lighting conditions.

9. Technical Comparison & Differentiation

The primary differentiating factors of this LED are its ultra-thin 0.8mm height and the use of an AlInGaP chip. Compared to traditional GaP (Gallium Phosphide) green LEDs, AlInGaP technology typically offers higher efficiency and brightness, resulting in greater luminous intensity for a given drive current. The thin profile is a critical advantage in modern, slim consumer electronics where z-height is severely limited.

10. Frequently Asked Questions (FAQ)

10.1 What is the difference between peak wavelength and dominant wavelength?

Peak Wavelength (λ_P): The single wavelength at which the emitted optical power is greatest. Dominant Wavelength (λ_d): The single wavelength of monochromatic light that matches the perceived color of the LED as defined by the CIE chromaticity diagram. λ_d is more relevant for color specification in display and indicator applications.

10.2 Can I drive this LED without a current-limiting resistor?

No. An LED is a current-driven device. Connecting it directly to a voltage source exceeding its forward voltage will cause excessive current to flow, potentially destroying the device instantly due to thermal runaway. Always use a series current-limiting resistor or a constant-current driver.

10.3 Why is binning important?

Binning ensures color and brightness uniformity within an application. Using LEDs from the same V_F, I_V, and λ_d bins guarantees that all indicators in a panel will have consistent appearance and performance, which is critical for user experience and product quality.

11. Practical Design Example

Scenario: Designing a status indicator for a portable device powered by a 3.3V rail. The goal is a medium-brightness green indicator.

1. Current Selection: Choose a drive current of 10mA for a balance of brightness and power consumption.
2. Resistor Calculation: Use the maximum V_F for safety: R = (3.3V - 2.4V) / 0.01A = 90 Ohms. The nearest standard value is 91 Ohms.
3. Bin Selection: Specify Bin N for luminous intensity (28-45 mcd) and Bin D for dominant wavelength (570.5-573.5 nm) to get a consistent, medium-brightness green.
4. Layout: Follow the recommended land pattern in the datasheet. Ensure the cathode pad (marked on the LED) is connected to ground via the current-limiting resistor.

12. Technology Introduction

This LED utilizes an AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor grown on a transparent substrate. When a forward voltage is applied, electrons and holes recombine in the active region of the chip, releasing energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy and thus the color of the emitted light, in this case, green. This material system is known for its high internal quantum efficiency, especially in the red, orange, yellow, and green spectral regions.

13. Industry Trends

The trend in SMD LEDs for consumer electronics continues toward miniaturization, higher efficiency, and improved color rendering. Package heights are shrinking below 0.8mm to enable ever-thinner devices. Efficiency improvements (more lumens per watt) reduce power consumption and thermal load. There is also a growing emphasis on tighter binning tolerances to meet the demanding color uniformity requirements of high-resolution displays and automotive lighting. The underlying semiconductor technology is also evolving, with ongoing research into materials like GaN-on-Si and micro-LEDs for next-generation applications.