LTST-C171KFKT-5A Orange SMD LED Datasheet - Dimensions 3.2x1.6x0.8mm - Voltage 1.7-2.3V - Power 75mW - English Technical Document

1. Product Overview

This document details the specifications for a high-performance, ultra-thin surface-mount chip LED. The device is designed for applications requiring a compact form factor, high brightness, and reliable operation in automated assembly processes. It utilizes an AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material to produce orange light, offering superior luminous efficiency compared to traditional technologies.

The primary advantages of this component include its minimal profile, compatibility with standard reflow soldering techniques, and suitability for high-volume automated placement equipment. It is intended for integration into a wide range of consumer electronics, indicators, backlighting, and general illumination applications where space and brightness are critical constraints.

2. Technical Specifications Deep Dive

2.1 Absolute Maximum Ratings

The device must not be operated beyond these limits to prevent permanent damage.

• Power Dissipation (Pd): 75 mW. This is the maximum total power the package can dissipate as heat under specified conditions.
• Peak Forward Current (I_FP): 80 mA. This is the maximum allowable instantaneous forward current, typically specified 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 maximum current that can be applied continuously.
• Reverse Voltage (V_R): 5 V. Exceeding this voltage in reverse bias can cause junction breakdown.
• Operating Temperature Range (T_opr): -30°C to +85°C. The ambient temperature range for reliable operation.
• Storage Temperature Range (T_stg): -55°C to +85°C.
• Infrared Reflow Soldering Condition: 260°C peak temperature for a maximum of 10 seconds. This defines the thermal profile tolerance during assembly.

2.2 Electro-Optical Characteristics

These parameters are measured at an ambient temperature (T_a) of 25°C and a standard test current (I_F) of 5 mA, unless otherwise noted.

• Luminous Intensity (I_V): Ranges from 11.2 mcd (minimum) to 45.0 mcd (maximum), with a typical value provided. Intensity is measured using a sensor filtered to match the photopic (CIE) human eye response curve.
• Viewing Angle (2θ_1/2): 130 degrees. This is the full angle at which the luminous intensity drops to half of its peak (on-axis) value, indicating a very wide viewing pattern.
• Peak Emission Wavelength (λ_P): 611 nm (typical). The wavelength at which the spectral power output is highest.
• Dominant Wavelength (λ_d): 597.0 nm to 612.0 nm. This is the single wavelength perceived by the human eye to define the color, derived from the CIE chromaticity diagram. The specific value for a given unit depends on its bin code.
• Spectral Line Half-Width (Δλ): 17 nm (typical). The spectral bandwidth measured at half the maximum intensity (Full Width at Half Maximum - FWHM).
• Forward Voltage (V_F): 1.7 V to 2.3 V at I_F = 5mA. The voltage drop across the LED when conducting current.
• Reverse Current (I_R): 10 μA (maximum) at V_R = 5V. The small leakage current when the device is reverse-biased.

3. Binning System Explanation

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

3.1 Forward Voltage Binning

Units are categorized by their forward voltage (V_F) at 5 mA.

• Bin E2: V_F = 1.70V - 1.90V
• Bin E3: V_F = 1.90V - 2.10V
• Bin E4: V_F = 2.10V - 2.30V

Tolerance within each bin is ±0.1V. Matching V_F bins is important when connecting multiple LEDs in parallel to ensure uniform current sharing.

3.2 Luminous Intensity Binning

Units are categorized by their luminous intensity (I_V) at 5 mA.

• Bin L: I_V = 11.2 mcd - 18.0 mcd
• Bin M: I_V = 18.0 mcd - 28.0 mcd
• Bin N: I_V = 28.0 mcd - 45.0 mcd

Tolerance within each bin is ±15%. This allows selection based on required brightness levels.

3.3 Dominant Wavelength Binning

Units are categorized by their dominant wavelength (λ_d) at 5 mA, which directly correlates to perceived color.

• Bin N: λ_d = 597.0 nm - 600.0 nm
• Bin P: λ_d = 600.0 nm - 603.0 nm
• Bin Q: λ_d = 603.0 nm - 606.0 nm
• Bin R: λ_d = 606.0 nm - 609.0 nm
• Bin S: λ_d = 609.0 nm - 612.0 nm

Tolerance within each bin is ±1 nm. Tight wavelength control is crucial for applications requiring precise color matching.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (e.g., Figure 1 for spectral distribution, Figure 6 for viewing angle), the typical relationships can be described.

Forward Current vs. Forward Voltage (I-V Curve): The V_F of an AlInGaP LED has a logarithmic relationship with I_F. It increases with current but exhibits a "knee" voltage below which very little current flows. Operating at the recommended 5mA test condition ensures stable performance within the specified V_F range.

Luminous Intensity vs. Forward Current: The light output (I_V) is approximately proportional to the forward current (I_F) within the device's operational limits. However, efficiency may drop at very high currents due to increased heat generation.

Temperature Dependence: The forward voltage (V_F) of LEDs typically decreases with increasing junction temperature (negative temperature coefficient). Conversely, luminous intensity generally decreases as temperature rises. Proper thermal management is essential to maintain consistent brightness and longevity.

Spectral Distribution: The AlInGaP material system produces a relatively narrow emission spectrum centered in the orange-red region (peak at ~611 nm). The dominant wavelength may shift slightly with changes in drive current and temperature.

5. Mechanical and Package Information

5.1 Package Dimensions

The device features an industry-standard EIA package outline. Key dimensions include a super-thin profile with a height of 0.80 mm. The length and width are typical for this class of chip LED. Detailed mechanical drawings specify all critical dimensions, including pad locations and tolerances (typically ±0.10 mm).

5.2 Pad Layout and Polarity

The datasheet includes a suggested soldering pad layout for PCB design. This layout is optimized for reliable solder joint formation during reflow and helps prevent tombstoning. The anode and cathode are clearly marked on the package, typically with a visual indicator such as a notch, dot, or cut corner. Correct polarity orientation is mandatory for device operation.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

The component is compatible with infrared (IR) reflow soldering processes. A suggested profile compliant with JEDEC standards for lead-free (Pb-free) assembly is provided. Key parameters include:

• Pre-heat: Ramp-up to 150-200°C.
• Soak/Pre-heat Time: Maximum 120 seconds to activate flux and minimize thermal shock.
• Peak Temperature: Maximum 260°C.
• Time Above Liquidus: The device should be exposed to the peak temperature for a maximum of 10 seconds. Reflow should not be performed more than twice.

The specific profile must be characterized for the actual 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 pad.
• Limit: Hand soldering should be performed only once to avoid thermal damage to the epoxy package and the semiconductor die.

6.3 Cleaning

Only specified cleaning agents should be used. Recommended solvents include ethyl alcohol or isopropyl alcohol at normal room temperature. The LED should be immersed for less than one minute. Unspecified chemical liquids may damage the package material or optical lens.

6.4 Storage and Handling

LEDs are moisture-sensitive devices (MSD).

• Sealed Package: Store at ≤30°C and ≤90% Relative Humidity (RH). The shelf life in the original moisture-proof bag with desiccant is one year.
• Opened Package: For components removed from their original packaging, the storage ambient should not exceed 30°C / 60% RH. It is recommended to complete IR reflow within 672 hours (28 days) of exposure. For longer exposure, store in a sealed container with desiccant or in a nitrogen desiccator. Components exposed for more than 672 hours should be baked at approximately 60°C for at least 20 hours before soldering to remove absorbed moisture and prevent "popcorning" during reflow.

7. Packaging and Ordering Information

The device is supplied in tape-and-reel packaging compatible with automated pick-and-place equipment.

• Reel Size: 7-inch diameter.
• Quantity per Reel: 3000 pieces.
• Minimum Order Quantity (MOQ): 500 pieces for remainder quantities.
• Tape Specifications: Compliant with ANSI/EIA 481-1-A-1994. Empty component pockets are sealed with a top cover tape.
• Quality: The maximum number of consecutive missing components in the tape is two.

The part number LTST-C171KFKT-5A encodes specific attributes: likely the series (LTST-C171), lens type (K=Water Clear), color (FKT=Orange AlInGaP), and binning codes (5A).

8. Application Recommendations

8.1 Typical Application Scenarios

• Status Indicators: Power, connectivity, or mode indicators in consumer electronics, appliances, and industrial equipment.
• Backlighting: Edge-lit or direct backlighting for small LCD panels, keypads, or symbols.
• Automotive Interior Lighting: Dashboard indicators, switch illumination (subject to qualification for specific automotive standards).
• Decorative Lighting: Accent lighting in devices where a thin profile is essential.

8.2 Design Considerations

• Current Drive: LEDs are current-operated devices. Use a constant current source or a current-limiting resistor in series with a voltage source to set the desired operating current. Do not connect directly to a voltage source without current limiting.
• Parallel Connection: When connecting multiple LEDs in parallel, slight variations in V_F can cause significant current imbalance, leading to uneven brightness and potential overstress of lower-V_F units. It is strongly recommended to drive each LED or series string with its own current-limiting resistor or use a dedicated multi-channel driver IC.
• Thermal Management: Although power dissipation is low, ensuring adequate PCB copper area for the solder pads aids in heat sinking, especially when operating near maximum ratings or in high ambient temperatures. This helps maintain luminous output and device reliability.
• ESD Protection: While not explicitly stated as sensitive in this datasheet, handling all semiconductor devices with appropriate ESD precautions is good practice.

9. Technical Comparison and Differentiation

This device differentiates itself primarily through its ultra-thin 0.80 mm height, which is advantageous for space-constrained applications like ultra-slim displays or wearable electronics. The use of AlInGaP technology provides higher luminous efficiency and better temperature stability for orange/red colors compared to older technologies like GaAsP. Its compatibility with standard IR reflow processes and 8mm tape on 7\" reels makes it ideal for high-volume, automated SMT assembly lines, reducing manufacturing cost and complexity.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the difference between Peak Wavelength and Dominant Wavelength?

A: Peak Wavelength (λ_P) is the physical point of highest energy output in the spectrum. Dominant Wavelength (λ_d) is a calculated value based on human color perception (CIE chart) and is the single wavelength that best describes the perceived color. λ_d is more relevant for color matching in applications.

Q: Why is binning important?

A: Manufacturing variations cause slight differences in V_F, intensity, and color between individual LEDs. Binning sorts them into groups with tightly controlled parameters. Selecting from the same bin ensures visual consistency (same color and brightness) and electrical consistency (similar V_F) in a final product.

Q: Can I drive this LED at 20mA continuously?

A: Yes. The maximum continuous forward current is 30 mA. Operating at 20mA is within specification. However, luminous intensity and forward voltage at 20mA will be higher than the 5mA test condition values. Refer to typical performance curves for guidance.

Q: How do I interpret the viewing angle of 130°?

A: A 130° viewing angle (2θ_1/2) is very wide. It means the LED emits light over a broad cone. The intensity is highest when looking straight on (0°), and when you move 65° off-axis (130°/2), the intensity drops to 50% of the on-axis value. This is suitable for applications where the LED needs to be visible from many angles.

11. Design and Usage Case Study

Scenario: Designing a multi-indicator panel for a portable medical device.

Requirements: Multiple orange status LEDs must be uniformly bright and identical in color. The device housing is very thin, limiting component height. Assembly is fully automated.

Design Choices Based on This Datasheet:

1. The 0.80mm height allows the LEDs to fit within the mechanical constraints.

2. To ensure uniform color, the designer specifies LEDs from a single, tight Dominant Wavelength bin (e.g., Bin Q: 603-606 nm).

3. To ensure uniform brightness, LEDs from a single Luminous Intensity bin (e.g., Bin M: 18-28 mcd) are selected.

4. To prevent brightness mismatch due to V_F variation, each LED is driven by its own current-limiting resistor connected to a common voltage rail, rather than connecting them directly in parallel.

5. The PCB layout follows the suggested pad dimensions to ensure reliable soldering during the IR reflow process specified in the document.

6. The manufacturing team follows the moisture handling guidelines, baking components that have been out of the bag for more than 28 days before assembly.

12. Technology Principle Introduction

This LED is based on AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material grown on a substrate. When a forward voltage is applied, electrons and holes are injected into the active region of the semiconductor junction. Their recombination 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—in this case, orange. The chip is encapsulated in an epoxy package that serves to protect the semiconductor die, provide mechanical stability, and act as a primary optical element. The "water clear" lens material does not alter the color but helps in extracting and directing the light. The thin profile is achieved through advanced chip design and packaging techniques.

13. Industry Trends and Developments

The trend in indicator and small-area lighting LEDs continues toward higher efficiency (more light output per unit of electrical power), smaller package sizes, and lower profiles to enable thinner end products. There is also a drive for improved color consistency and tighter binning from manufacturers. The adoption of lead-free (Pb-free) and RoHS-compliant materials and processes, as seen in this component's reflow profile, is now standard. Furthermore, advancements in chip design and phosphor technology (though not used in this monochromatic AlInGaP device) are pushing the boundaries of what is possible in terms of brightness and color rendering for white LEDs, which influences the entire market's expectations for performance and reliability.