SMD LED LTST-C191KSKT Datasheet - Size 1.6x0.8x0.55mm - Voltage 1.8-2.4V - Yellow Color - English Technical Document

1. Product Overview

This document provides the complete technical specifications for a surface-mount device (SMD) LED lamp. Designed for automated printed circuit board (PCB) assembly, this component is ideal for space-constrained applications across a wide range of electronic equipment.

1.1 Features

• Compliant with RoHS environmental standards.
• Exceptionally thin package profile of 0.55 mm.
• Utilizes an ultra-bright Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor chip.
• Supplied in industry-standard 8mm tape on 7-inch diameter reels for automated handling.
• Compatible with standard EIA package outlines.
• Input logic levels are compatible with integrated circuits (I.C.).
• Designed for compatibility with automatic pick-and-place assembly equipment.
• Suitable for use in infrared (IR) reflow soldering processes.

1.2 Applications

This LED is suitable for numerous applications, including but not limited to:

• 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 lighting and symbolic illumination.

2. Package Dimensions and Configuration

The device features a compact, rectangular SMD package. The lens is water clear, while the light source emits a yellow color using AlInGaP technology. Critical dimensional tolerances are typically ±0.1 mm unless otherwise specified on the detailed mechanical drawing.

3. Ratings and Characteristics

3.1 Absolute Maximum Ratings

Ratings are specified at an ambient temperature (Ta) of 25°C. Exceeding these values may cause permanent damage.

• 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
• Current Derating: Linear reduction from 50°C at 0.4 mA/°C
• Reverse Voltage (V_R): 5 V
• Operating Temperature Range (T_opr): -55°C to +85°C
• Storage Temperature Range (T_stg): -55°C to +85°C
• Infrared Reflow Soldering: Withstand 260°C peak temperature for 10 seconds.

3.2 Suggested IR Reflow Profile

For lead-free (Pb-free) soldering processes, a profile with a peak temperature of 260°C for a maximum of 10 seconds is recommended. The exact thermal profile should be characterized for the specific PCB design, solder paste, and oven used, following JEDEC standards and solder paste manufacturer guidelines.

3.3 Electrical and Optical Characteristics

Typical performance is measured at Ta=25°C and I_F=20mA, unless noted.

• Luminous Intensity (I_V): 28.0 - 180.0 mcd (measured with a CIE eye-response filter).
• Viewing Angle (2θ_1/2): 130 degrees (the off-axis angle where intensity is half the on-axis value).
• Peak Emission Wavelength (λ_P): 588 nm.
• Dominant Wavelength (λ_d): 584.5 - 597.0 nm (defines the perceived color).
• Spectral Line Half-Width (Δλ): 15 nm.
• Forward Voltage (V_F): 1.8 - 2.4 V.
• Reverse Current (I_R): 10 μA (max) at V_R=5V.
• Capacitance (C): 40 pF (typical) at V_F=0V, f=1MHz.

Note on ESD: This device is sensitive to electrostatic discharge (ESD). Proper ESD precautions, including the use of grounded wrist straps and anti-static workstations, are mandatory during handling.

4. Bin Rank System

Components are sorted into bins based on key parameters to ensure consistency in production runs. The bin code is part of the full product ordering information.

4.1 Forward Voltage (V_F) Rank

• Bin F2: 1.8V (Min) to 2.1V (Max)
• Bin F3: 2.1V (Min) to 2.4V (Max)
• Tolerance: ±0.1V per bin.

4.2 Luminous Intensity (I_V) Rank

• Bin N: 28.0 mcd (Min) to 45.0 mcd (Max)
• Bin P: 45.0 mcd (Min) to 71.0 mcd (Max)
• Bin Q: 71.0 mcd (Min) to 112.0 mcd (Max)
• Bin R: 112.0 mcd (Min) to 180.0 mcd (Max)
• Tolerance: ±15% per bin.

4.3 Hue / Dominant Wavelength (λ_d) Rank

• Bin H: 584.5 nm (Min) to 587.0 nm (Max)
• Bin J: 587.0 nm (Min) to 589.5 nm (Max)
• Bin K: 589.5 nm (Min) to 592.0 nm (Max)
• Bin L: 592.0 nm (Min) to 594.5 nm (Max)
• Bin M: 594.5 nm (Min) to 597.0 nm (Max)
• Tolerance: ±1 nm per bin.

5. Typical Performance Curves

Graphical data is provided to illustrate device behavior under various conditions. These curves are essential for detailed circuit design and thermal management.

• Relative Luminous Intensity vs. Forward Current: Shows the non-linear relationship between drive current and light output.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the reduction in light output as junction temperature increases.
• Forward Voltage vs. Forward Current: Illustrates the diode's I-V characteristic curve.
• Spectral Distribution: Depicts the relative radiant power across the wavelength spectrum, centered around the peak wavelength.

6. User Guide and Handling

6.1 Cleaning

If cleaning is necessary after soldering, use only specified solvents. Immerse the LED in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute. Do not use ultrasonic cleaning or unspecified chemicals.

6.2 Recommended PCB Pad Layout

A detailed land pattern design is provided to ensure proper solder joint formation, component alignment, and thermal relief during reflow. Adhering to this pattern is critical for manufacturing yield and long-term reliability.

6.3 Tape and Reel Packaging

The components are supplied in embossed carrier tape sealed with a cover tape, wound onto 7-inch (178 mm) diameter reels. Standard packaging contains 5000 pieces per reel. The packaging conforms to ANSI/EIA-481 specifications.

7. Important Cautions

7.1 Application Scope

This product is designed for standard commercial and industrial electronic equipment. It is not intended for safety-critical applications where failure could lead to direct jeopardy of life or health (e.g., aviation, medical life-support, transportation control) without prior consultation and specific qualification.

7.2 Storage Conditions

Sealed Package: Store at ≤ 30°C and ≤ 90% Relative Humidity (RH). The shelf life is one year when the moisture barrier bag (with desiccant) remains unopened.
Opened Package: For components removed from their sealed bag, the storage environment must not exceed 30°C / 60% RH. Components should be subjected to IR reflow soldering within 672 hours (28 days) of exposure to ambient air (MSL 2a). For longer exposures, bake at approximately 60°C for at least 20 hours before assembly to remove absorbed moisture and prevent \"popcorning\" during reflow.

7.3 Soldering Instructions

Reflow Soldering:
- Pre-heat: 150°C to 200°C.
- Pre-heat Time: Maximum 120 seconds.
- Peak Temperature: Maximum 260°C.
- Time Above 260°C: Maximum 10 seconds.
- Maximum Number of Reflow Passes: Two.
Hand Soldering (Iron):
- Iron Tip Temperature: Maximum 300°C.
- Soldering Time per Lead: Maximum 3 seconds.
- Maximum Number of Hand-solder Passes: One.

8. Technical Deep Dive and Design Considerations

8.1 Photometric and Colorimetric Analysis

The use of an AlInGaP chip is a key differentiator. Compared to traditional phosphor-converted or older semiconductor materials, AlInGaP offers higher intrinsic efficiency in the amber-yellow-green spectrum, resulting in the \"ultra-bright\" characteristic. The dominant wavelength binning ensures tight color consistency, which is crucial for applications like status indicators where color perception must be uniform across multiple units. The wide 130-degree viewing angle makes this LED suitable for applications requiring broad visibility, not just a narrow beam.

8.2 Electrical Design and Driving

The forward voltage range of 1.8V to 2.4V at 20mA is relatively low, making it compatible with direct drive from many logic-level outputs (3.3V, 5V) when used with a simple current-limiting resistor. The derating curve for forward current is critical: the maximum allowable continuous current decreases linearly from 30mA at 50°C ambient. For reliable operation at high ambient temperatures or in enclosed spaces, the drive current must be reduced accordingly to keep the junction temperature within safe limits and prevent accelerated lumen depreciation.

8.3 Thermal and Mechanical Design

The ultra-thin 0.55mm profile is a significant advantage for modern, slim devices. However, the minimal package mass also means it has limited thermal mass. Heat dissipation is primarily through the solder pads into the PCB. Therefore, the recommended PCB pad design and the use of thermal relief connections or small copper pours under the device are important for managing junction temperature. Ensuring a high-quality solder joint is paramount for both electrical connection and thermal conduction.

8.4 Manufacturing and Assembly Compatibility

Compliance with EIA standards and packaging in 8mm tape ensures seamless integration into high-volume, automated SMT assembly lines. The specified compatibility with IR reflow processes is validated, but designers must carefully develop their oven profile. The pre-heat stage is vital to slowly ramp temperature and minimize thermal shock, while the time above liquidus (TAL) and peak temperature must be controlled to fully melt the solder paste without damaging the LED's epoxy lens or internal wire bonds.

8.5 Comparison and Selection Guidance

When selecting an LED, engineers must balance several parameters from the datasheet. For high-brightness needs, specify a bin from the upper end of the I_V range (e.g., Q or R). For applications sensitive to power consumption or heat generation in a series string, a lower V_F bin (F2) is preferable. For strict color matching, a narrow λ_d bin (e.g., J or K) should be selected and maintained throughout production. The 0.55mm height is a key advantage over standard 0.6mm or 0.8mm LEDs in ultra-thin products but may require more precise control of solder paste volume and reflow profile to avoid tombstoning.

9. Frequently Asked Questions (FAQ)

Q: What is the typical operating current for this LED?
A: The characteristics are tested at 20mA, which is a common operating point. It can be driven up to the absolute maximum of 30mA DC with appropriate thermal management, but lifetime and efficiency may be optimized at lower currents.

Q: How do I interpret the bin codes when ordering?
A: The full product part number includes codes for V_F, I_V, and λ_d bins. You must specify the desired combination (e.g., F2, R, K) to get the exact electrical and optical performance required for your design.

Q: Can I use this LED for automotive interior lighting?
A> While it operates within a -55°C to +85°C range, automotive applications often require specific AEC-Q102 qualification for reliability under harsh environmental stress, which is not implied by this commercial datasheet. Consultation with the manufacturer for automotive-grade products is necessary.

Q: Why is the storage condition after opening the bag so important?
A: SMD packages can absorb moisture from the air. During the high heat of reflow soldering, this trapped moisture can vaporize rapidly, causing internal delamination or cracking (\"popcorning\"). The 672-hour floor life and baking procedure are critical controls to prevent this failure mode.