LTST-C281KGKT Chip LED Datasheet - Dimensions 2.8x1.2x0.35mm - Voltage 2.4V - Power 75mW - Green Color - English Technical Document

1. Product Overview

This document provides the complete technical specifications for the LTST-C281KGKT, an ultra-thin, surface-mount chip LED designed for modern electronic applications requiring high brightness and a compact form factor. The device utilizes an AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material to produce a green light output, offering superior luminous efficiency compared to traditional LED technologies. Its primary design goals are to enable high-density PCB layouts, compatibility with automated assembly processes, and reliable performance under standard reflow soldering conditions.

The core advantages of this component include its exceptionally low profile of 0.35mm, which is critical for applications with strict height limitations such as ultra-thin displays, mobile devices, and backlighting units. It is classified as a green product and complies with RoHS (Restriction of Hazardous Substances) directives, making it suitable for environmentally conscious designs. The package is supplied on industry-standard 8mm tape mounted on 7-inch diameter reels, facilitating high-speed pick-and-place manufacturing.

2. Technical Parameter Deep-Dive

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed and should be avoided for reliable long-term performance.

• Power Dissipation (Pd): 75 mW. This is the maximum amount of power the LED package can dissipate as heat at an ambient temperature (Ta) of 25°C. Exceeding this limit risks overheating the semiconductor junction, leading to accelerated degradation or catastrophic failure.
• DC Forward Current (IF): 30 mA. The maximum continuous forward current that can be applied to the LED.
• Peak Forward Current: 80 mA. Wannan yana yiwuwa ne kawai a ƙarƙashin yanayin bugun jini tare da tsauraran zagayowar aiki na 1/10 da faɗin bugun jini na 0.1ms. Wannan ƙimar tana da alaƙa da yanayin haɗawa ko taƙaitaccen nuna sigina.
• Reverse Voltage (VR): 5 V. Yin amfani da ƙarfin lantarki na baya wanda ya wuce wannan ƙimar zai iya haifar da rushewar haɗin PN na LED.
• Operating Temperature Range: -30°C to +85°C. The ambient temperature range within which the LED is specified to operate correctly.
• Storage Temperature Range: -40°C to +85°C. The temperature range for non-operational storage.
• Infrared Soldering Condition: 260°C for 10 seconds. This defines the peak temperature and time profile the package can withstand during a lead-free reflow soldering process.

2.2 Electrical & Optical Characteristics

These parameters are measured at a standard test condition of Ta=25°C and IF=20mA, unless otherwise noted. They define the typical performance of the device.

• Luminous Intensity (Iv): 35.0 mcd (Typical), with a minimum of 18.0 mcd. This is the measure of the perceived power of light emitted in a specific direction. It is measured using a sensor-filter combination that approximates the photopic (CIE) human eye response curve.
• Viewing Angle (2θ1/2): 130 degrees (Typical). This is the full angle at which the luminous intensity drops to half of its value at the central axis (0°). A wide viewing angle like this indicates a more diffuse, lambertian-like emission pattern suitable for area illumination.
• Peak Emission Wavelength (λP): 574 nm. This is the wavelength at which the spectral power distribution of the emitted light reaches its maximum intensity.
• Dominant Wavelength (λd): 571 nm (Typical at IF=20mA). This is derived from the CIE chromaticity diagram and represents the single wavelength that best describes the perceived color of the light. It is a more accurate representation of color than peak wavelength.
• Spectral Line Half-Width (Δλ): 15 nm. This is the width of the emission spectrum at half of its maximum intensity (Full Width at Half Maximum - FWHM). A narrower half-width indicates a more spectrally pure, saturated color.
• Forward Voltage (VF): 2.4 V (Typical), with a maximum of 2.4 V at IF=20mA. This is the voltage drop across the LED when operating at the specified current.
• Reverse Current (IR): 10 μA (Maximum) at VR=5V. This is the small leakage current that flows when the specified reverse voltage is applied.

3. Binning System Explanation

To ensure consistency in mass production, LEDs are sorted into performance bins based on key parameters. The LTST-C281KGKT uses a three-dimensional binning system.

3.1 Forward Voltage Binning

Units are in Volts (V) measured at IF=20mA. Tolerance on each bin is ±0.1V.

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

This binning allows designers to select LEDs with closely matched Vf for applications requiring uniform brightness in series strings or precise current regulation.

3.2 Luminous Intensity Binning

Units are in millicandelas (mcd) measured at IF=20mA. Tolerance on each bin is ±15%.

• Bin M: 18.0 mcd (Min) - 28.0 mcd (Max)
• Bin N: 28.0 mcd - 45.0 mcd
• Bin P: 45.0 mcd - 71.0 mcd
• Bin Q: 71.0 mcd - 112.0 mcd

This classification groups LEDs by their brightness output, enabling selection for applications with specific minimum intensity requirements.

3.3 Dominant Wavelength Binning

Units are in nanometers (nm) measured at IF=20mA. Tolerance for each bin is ±1 nm.

• Bin C: 567.5 nm (Min) - 570.5 nm (Max)
• Bin D: 570.5 nm - 573.5 nm
• Bin E: 573.5 nm - 576.5 nm

Wannan binning yana tabbatar da daidaiton launi. LEDs a cikin bin ɗaya za su yi kama da kusan inuwa iri ɗaya na kore ga idon mutum, wanda yake da mahimmanci ga tsararrun LED da yawa da nunin.

4. Performance Curve Analysis

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

Luminous Intensity vs. Forward Current (I-V Curve): For AlInGaP LEDs, the luminous intensity typically increases in a near-linear relationship with forward current up to a point, after which efficiency may drop due to increased heat. Operating at or below the recommended 20mA ensures optimal efficiency and longevity.

Forward Voltage vs. Temperature: The forward voltage (Vf) of an LED has a negative temperature coefficient; it decreases as the junction temperature increases. This must be considered in constant-voltage drive circuits, as a rise in temperature could lead to an increase in current.

Spectral Distribution: The emission spectrum is centered around the dominant wavelength (571nm typical). The 15nm half-width indicates a relatively narrow band of green light, contributing to good color purity. The peak wavelength may shift slightly (typically to longer wavelengths) with increasing junction temperature and drive current.

5. Mechanical & Package Information

5.1 Package Dimensions

The device conforms to an EIA standard package outline. Key dimensional features include an overall height of 0.35mm, making it an "extra thin" component. The length and width are defined in the detailed package drawing (referenced in the datasheet). All dimensions are in millimeters with a standard tolerance of ±0.10mm unless otherwise specified. The lens material is water-clear, which maximizes light extraction and provides the intended viewing angle.

5.2 Polarity Identification & Pad Design

The datasheet includes a suggested soldering pad layout. Proper pad design is critical for achieving a reliable solder joint, ensuring correct alignment during reflow, and managing heat dissipation. The cathode is typically marked on the device, often by a notch, a green dot, or a different lead length/shape. The recommended pad dimensions help prevent tombstoning (component standing up on one end) during reflow and facilitate good solder fillets.

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Profile

A suggested infrared (IR) reflow profile for lead-free (Pb-free) processes is provided. This profile is compliant with JEDEC standards and serves as a generic target. Key parameters include:

• Pre-heat: 150-200°C.
• Pre-heat Time: Maximum 120 seconds to allow for uniform heating and activation of flux.
• Peak Temperature: Maximum 260°C. The component is rated for this temperature for 10 seconds.
• Time Above Liquidus (TAL): The time within which the solder is molten must be controlled to form good intermetallic bonds without over-stressing the component.

It is emphasized that the optimal profile depends on the specific PCB design, solder paste, and oven used. Characterization for the specific assembly line is recommended.

6.2 Hand Soldering

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

• Zazzabi na Gishiri: Matsakaicin 300°C.
• Lokacin Gishiri: Maximum 3 seconds per pad. This should be performed only once to avoid thermal damage to the LED chip and plastic package.

6.3 Storage & Handling

• ESD (Electrostatic Discharge) Precautions: The device is sensitive to ESD. Handling should be performed using wrist straps, anti-static mats, and grounded equipment.
• Moisture Sensitivity: As a surface-mount plastic package, it is sensitive to moisture absorption. If the original sealed moisture-barrier bag is opened, the components should be subjected to IR reflow soldering within 672 hours (28 days) under recommended storage conditions (≤30°C, ≤60% RH). For storage beyond this period or in uncontrolled environments, baking at approximately 60°C for at least 20 hours is required before soldering to prevent "popcorning" (package cracking due to rapid vapor expansion during reflow).

7. Packaging & Ordering Information

The standard packaging is 8mm wide embossed carrier tape on 7-inch (178mm) diameter reels. Each reel contains 5000 pieces. For quantities less than a full reel, a minimum packing quantity of 500 pieces applies for remainder stock. The tape and reel specifications are in accordance with ANSI/EIA-481. Empty pockets in the tape are sealed with a top cover tape to protect components. The maximum allowable number of consecutive missing components (empty pockets) is two, as per the standard.

8. Application Notes & Design Considerations

8.1 Typical Application Scenarios

This LED is suitable for a wide range of applications including, but not limited to: status indicators on consumer electronics (phones, tablets, laptops), backlighting for small LCDs or keypads, decorative lighting, automotive interior lighting, and general-purpose panel indicators. Its thin profile makes it ideal for space-constrained designs.

8.2 Drive Circuit Design

Current Limiting is Essential: LEDs are current-driven devices. A series current-limiting resistor or a constant-current driver circuit must always be used to prevent exceeding the maximum DC forward current (30mA). The resistor value can be calculated using Ohm's Law: R = (Vsupply - Vf_LED) / I_desired. Using the typical Vf of 2.4V and a desired current of 20mA with a 5V supply: R = (5V - 2.4V) / 0.020A = 130 Ohms. A standard 130 or 150 Ohm resistor would be appropriate.

Thermal Management: Although power dissipation is low (75mW max), ensuring adequate PCB copper area around the thermal pads (if specified) or general trace width helps dissipate heat, maintaining LED efficiency and lifespan, especially in high ambient temperature environments or when driven at higher currents.

8.3 Cleaning

Idan ake buƙatar tsaftacewa bayan gudanar da aikin gini, kawai dole ne a yi amfani da kayan da aka ƙayyade. Yin nutsewa cikin LED a cikin barasa na ethyl ko isopropyl a yanayin zafi na yau da kullun na ƙasa da minti ɗaya yana da kyau. Yin amfani da kayan tsaftacewa na sinadarai waɗanda ba a ƙayyade ba ko masu tsattsauran ra'ayi na iya lalata fakitin filastik da ruwan tabarau, wanda zai haifar da canza launi ko fashewa.

9. Technical Comparison & Differentiation

Babban abubuwan da suka bambanta na wannan ɓangaren sune ultra-thin 0.35mm height and the use of AlInGaP technology for the green chip.

• vs. Traditional LED Packages: Compared to older LED packages (e.g., 3mm or 5mm through-hole), this SMD chip LED offers a dramatically smaller footprint and profile, enabling modern miniaturized designs. It also allows for fully automated assembly.
• AlInGaP vs. Other Technologies: For green and yellow colors, AlInGaP LEDs generally offer higher luminous efficiency and better temperature stability compared to older technologies like Gallium Phosphide (GaP). This results in brighter output and more consistent color over a range of operating conditions.
• Water-Clear Lens: The water-clear (non-diffused) lens provides the highest possible light output and a well-defined viewing angle pattern, as opposed to a diffused lens which scatters light more broadly for a softer appearance.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED with 3.3V without a resistor?
A: No. Without a current-limiting resistor, applying 3.3V directly would likely force a current far exceeding the 30mA maximum, instantly damaging the LED. Always use a series resistor or constant-current driver.

Q: Menene bambanci tsakanin Peak Wavelength (574nm) da Dominant Wavelength (571nm)?
A: Peak wavelength shine inda ƙarfin bakan ya fi girma. Dominant wavelength ana samunsa daga fahimtar launi (CIE diagram) kuma ya fi wakiltar ainihin launin da ake gani. Sau da yawa suna kusa amma ba iri ɗaya ba, musamman ga LEDs masu bakan da ba su da daidaito.

Q: Kusurwar kallo shine digiri 130. Shin wannan yana nufin haske yana bayyane ne kawai a cikin wannan mazugi?
A: No, light is emitted in a near-hemispherical pattern, but its intensity falls off with angle. The 130-degree specification is the angle where intensity is half of the on-axis (0°) value. Some light is still visible outside this angle, but it is significantly dimmer.

Q: Why is the storage time limited to 672 hours after opening the bag?
A> This is due to moisture sensitivity level (MSL). The plastic package can absorb moisture from the air. During the high heat of reflow soldering, this moisture can turn to steam rapidly, causing internal pressure that can crack the package ("popcorning"). The 672-hour limit assumes proper storage; baking removes the absorbed moisture.

11. Practical Design & Usage Examples

Example 1: Multi-LED Status Bar: Designing a 5-segment status bar on a portable device. To ensure uniform brightness and color, specify LEDs from the same Luminous Intensity bin (e.g., all from Bin N) and the same Dominant Wavelength bin (e.g., all from Bin D). Drive them with a common constant-current circuit or individual resistors calculated using the maximum Vf from the Forward Voltage bin (e.g., Bin 8, 2.4V) to guarantee all LEDs light up even with worst-case Vf variation.

Example 2: Backlighting a Thin Membrane Switch: The 0.35mm height is crucial here. The LED can be placed directly behind a translucent icon on a membrane layer with almost no added thickness. A current of 10-15mA (instead of 20mA) might be sufficient, reducing power consumption and heat generation while still providing adequate illumination in a dark environment.

12. Operating Principle

The LTST-C281KGKT is a semiconductor light source based on a PN junction formed from AlInGaP materials. When a forward voltage exceeding the junction's built-in potential is applied, electrons from the N-type region and holes from the P-type region are injected into the active region. When these charge carriers recombine, energy is released in the form of photons (light). The specific energy bandgap of the AlInGaP alloy determines the wavelength (color) of the emitted photons, which in this case is in the green region of the visible spectrum (~571nm). The water-clear epoxy package acts as a lens, shaping the light output and providing mechanical and environmental protection for the fragile semiconductor chip.

13. Mienendo ya Teknolojia

Uundaji wa LED kama LTST-C281KGKT unafuata mienendo kadhaa muhimu ya tasnia:

• Miniaturization: Continuous reduction in package size (footprint and height) to enable ever-smaller and thinner electronic products.
• Increased Efficiency: Advancements in epitaxial growth and chip design (like the use of AlInGaP) yield higher lumens per watt (lm/W), reducing power consumption for a given light output.
• Enhanced Reliability & Compatibility: Improvements in package materials and construction allow for higher temperature tolerance, such as withstanding 260°C lead-free reflow profiles, which is now an industry standard.
• Standardization & Automation: Adoption of standard package outlines (EIA) and tape-and-reel packaging is critical for compatibility with high-volume, automated surface-mount technology (SMT) assembly lines, driving down manufacturing costs.