LTST-C155TGKFKT Dual-Color SMD LED Datasheet - 1.10mm Ultra-Thin Height - Green 3.3V/Orange 2.0V - 76mW/75mW - Technical Documentation

1. Product Overview

This document provides the complete technical specifications for the LTST-C155TGKFKT model dual-color surface-mount device (SMD) LED. This device integrates two different semiconductor chips within an ultra-thin package: an InGaN (Indium Gallium Nitride) chip for emitting green light and an AlInGaP (Aluminum Indium Gallium Phosphide) chip for emitting orange light. Its design aims to meet modern electronic assembly processes and application scenarios requiring compact dual-color indication.

The core advantage of this LED lies in its extremely low 1.10mm package height, which is crucial for space-constrained designs such as consumer electronics, automotive interiors, and portable devices. It is an environmentally friendly product compliant with the ROHS (Restriction of Hazardous Substances) directive. The device is supplied in 8mm carrier tape form, wound onto 7-inch diameter reels, fully compatible with high-speed automated pick-and-place equipment used in mass production. Its design is also compatible with infrared (IR) reflow soldering processes, meeting lead-free (Pb-free) assembly standards.

Target markets encompass various electronic devices requiring reliable dual-state indication, including office automation equipment, communication devices, home appliances, industrial control panels, and automotive dashboard indicator lights. Independent anode/cathode pins for each color allow for independent control, enabling status signal indication, power indication, or multi-state user interface feedback.

2. Bincike Cikakken na Sigogi na Fasaha

2.1 Madaidaicin Matsakaici na Cikakke

Operating the device beyond these limits may cause permanent damage. Ratings are specified at an ambient temperature (Ta) of 25°C.

• Power Dissipation (Pd):76 mW for the green chip, 75 mW for the orange chip. This parameter defines the maximum allowable thermal dissipation power. Exceeding this value may lead to excessive junction temperature and accelerated performance degradation.
• Peak Forward Current (I_FP):100 mA for green, 80 mA for orange. This is the maximum permissible pulse current at a 1/10 duty cycle and 0.1ms pulse width. It is significantly higher than the continuous DC rating and is suitable for brief high-brightness pulse applications.
• DC Forward Current (I_F):20 mA for green, 30 mA for orange. This is the recommended continuous operating current for standard brightness and long-term reliability.
• Reverse Voltage (V_R):Both colors operate at 5 V. The device provides limited reverse bias protection. It is not designed for AC operation or reverse bias conditions in circuit design.
• Operating Temperature Range:-20°C to +80°C. The LED can operate normally within this ambient temperature range.
• Storage Temperature Range:-30°C to +100°C.
• Infrared Soldering Conditions:Can withstand a peak temperature of 260°C for up to 10 seconds, which is the standard condition for lead-free reflow soldering profiles.

2.2 Halayen Lantarki da Na'urar Gani

These are typical performance parameters measured under conditions of Ta=25°C, I_F=20mA, unless otherwise specified.

• Luminous Intensity (I_V):This is perceived brightness. For green, it ranges from a minimum of 71.0 mcd to a maximum of 280.0 mcd. For orange, it ranges from 45.0 mcd to 180.0 mcd. The intensity of a specific unit is determined by its binning code (see Section 3). Measurement follows the CIE photopic human eye response curve.
• Viewing Angle (2θ_1/2):) is typically 130 degrees for both colors. This wide viewing angle, defined as the full angle where luminous intensity drops to half of its axial value, makes the LED suitable for applications requiring visibility from a wide range of viewing angles.
• Peak Emission Wavelength (λ_P):) is typically 525 nm for green (InGaN) and 611 nm for orange (AlInGaP). This is the wavelength corresponding to the highest point of the emission spectrum.
• Dominant Wavelength (λ_d):) is typically 525 nm for green and 605 nm for orange. This value, derived from the CIE chromaticity diagram, is the single wavelength that best represents the perceived color of the light.
• Spectral line half-width (Δλ):Green is typically 35.0 nm, orange is typically 17.0 nm. The orange AlInGaP chip has a narrower spectral bandwidth, which can produce more saturated and purer colors compared to the wider green spectrum.
• Forward voltage (V_F):Green is typically 3.3 V (max 3.5 V) at 20mA. Orange is typically 2.0 V (max 2.4 V) at 20mA. The lower V_Fof the orange chip means lower power consumption at the same drive current. These values are crucial for designing the current-limiting resistor in the drive circuit.
• Reverse current (I_R):When a 5V reverse voltage (V_R) is applied, green is max 10 µA, orange is max 20 µA. This test is for characterization only; the device is not intended for reverse operation.

3. Bayanin Tsarin Rarraba

LEDs are binned according to their measured luminous intensity to ensure consistency within production batches. For applications requiring specific brightness levels, the binning code is a key part of the ordering information.

3.1 Green Chip Strength Grading

• Binning Code Q:Minimum 71.0 mcd, maximum 112.0 mcd.
• Binning Code R:Minimum 112.0 mcd, maximum 180.0 mcd.
• Binning Code S:Minimum 180.0 mcd, maximum 280.0 mcd.

3.2 Orange Chip Strength Grading

• Binning Code P:Minimum 45.0 mcd, maximum 71.0 mcd.
• Binning Code Q:Minimum 71.0 mcd, maximum 112.0 mcd.
• Binning Code R:Minimum 112.0 mcd, maximum 180.0 mcd.

Tolerance:The intensity tolerance within each defined bin is +/-15%. This accounts for minor measurement and production variations.

4. Performance Curve Analysis

The datasheet references typical performance curves, which are crucial for understanding device behavior under non-standard conditions. Although the specific graphs are not reproduced in the text, their implications are analyzed as follows.

4.1 Forward Current vs. Forward Voltage (I-V Curve)

The I-V curve for each chip (green/orange) will show the typical exponential diode relationship. The curve knee voltage for the orange AlInGaP chip (approx. 2.0V) is lower than that of the green InGaN chip (approx. 3.3V). This graph is crucial for determining the necessary power supply voltage and designing a constant current driver to ensure brightness stability across units and temperatures.

4.2 Luminous Intensity vs. Forward Current

This curve typically shows a near-linear relationship between drive current and light output within the recommended operating range (up to 20-30mA). Driving the LED above its rated DC current increases brightness at the cost of higher power consumption, reduced efficiency, and potentially shortened lifetime due to increased junction temperature.

4.3 Spectral Distribution

The referenced spectral plot will illustrate the difference in spectral half-width between the green (broader, ~35nm) and orange (narrower, ~17nm) chips. The narrow emission of the orange chip is characteristic of AlInGaP technology, offering high color purity, which is often desirable for indicator applications where color differentiation is critical.

4.4 Temperature Dependence

LED performance is sensitive to temperature. Although not detailed in the provided text, typical characteristics include: luminous intensity decreases as junction temperature rises; the dominant wavelength shifts slightly (typically a few nanometers); and the forward voltage (V_F) decreases with increasing temperature. For applications exposed to high ambient temperatures, these factors must be considered in thermal management and circuit design.

5. Mechanical and Packaging Information

5.1 Girman Kunshewa

This LED adopts an industry-standard EIA package outline. A key mechanical feature is its ultra-low profile with a maximum height (H) of 1.10 mm. All other critical dimensions required for PCB pad design, such as length, width, and lead pitch, are provided in the package drawing, with a standard tolerance of ±0.10 mm unless otherwise specified.

5.2 Rarraba Fil

The device has four pins. For the LTST-C155TGKFKT model:

• Pins 1 and 3 are assigned toGreenInGaN chip (anode and cathode).
• Pins 2 and 4 are assigned toOrangeAlInGaP chip (anode and cathode).

This configuration allows the two LEDs to be wired and controlled completely independently.

5.3 Shawarar Tsarin Fil ɗin Walda

Provides recommended PCB pad patterns (footprints). Adhering to these patterns is crucial for achieving reliable solder joints during reflow soldering, preventing tombstoning (component standing), and ensuring proper alignment. The pad design takes into account solder fillet formation and heat dissipation.

6. Jagorar Walda da Haɗawa

6.1 Reflow Soldering Profile

Includes a suggested lead-free process infrared (IR) reflow soldering profile. This profile complies with JEDEC standards, and its key parameters include:

• Preheat:150°C to 200°C.
• Preheat Time:Mafi tsawon dakika 120, don dumama hankali allon daɓaɓɓun da kayan aiki, don rage girgizar zafi.
• Matsakaicin zafi:Mafi girma 260°C.
• Lokacin sama da ruwa:Kayan aiki suna fuskantar matsakaicin zafi har zuwa dakika 10 kawai. Aiwatar da sake narkewa ya kamata ya kasance sau biyu kawai.

Saboda ƙirar allon, kayan aiki, da man gini sun bambanta, wannan jadawalin yana aiki ne kawai azaman manufa ta gama gari. Ana ba da shawarar yin nazarin halayen takamaiman allon.

6.2 Manual Soldering

Idan dole ne a yi walda da hannu, yi amfani da ƙarfe mai walda wanda bai wuce 300°C ba. Lokacin walda kowane ƙafar ya kamata a iyakance shi zuwa dakika 3 kawai, kuma ya kamata a yi shi sau ɗaya kawai, don hana lalacewar zafi ga kullin filastik da igiyoyin haɗin ciki.

6.3 Cleaning

Do not use unspecified chemical cleaners. If cleaning is required after soldering, immerse the LED in ethanol or isopropyl alcohol at room temperature for no more than one minute. Strong solvents may damage the epoxy lens or package marking.

6.4 Electrostatic Discharge (ESD) Precautions

LEDs are sensitive to electrostatic discharge and voltage surges. It is recommended to wear a grounded wrist strap or anti-static gloves during handling. All assembly equipment and workstations must be properly grounded to prevent ESD damage, which may not be immediately apparent but can reduce long-term reliability.

7. Bayanin Kunshin da Oda

7.1 Ma'auni na Carrier Tape da Reel

Components are supplied on 7-inch (178 mm) diameter reels in embossed carrier tape per ANSI/EIA-481 standard.

• Carrier tape width:8 mm.
• Quantity per reel:3000 pieces.
• Minimum Order Quantity (MOQ):Remaining quantity is 500 pieces.
• Cover tape:An empty component cavity is sealed with top cover tape.
• Missing component:According to reel specifications, a maximum of two consecutive missing LEDs (empty cavities) is allowed.

7.2 Yanayin Ajiya

Sealed package:Store at ≤30°C and ≤90% relative humidity (RH). Shelf life in a sealed moisture barrier bag with desiccant is one year.Opened package:For components removed from the original package, the storage environment must not exceed 30°C / 60% RH. It is recommended to complete infrared reflow soldering within one week after opening.Long-term Storage (Opened):Store in a sealed container with desiccant or in a nitrogen dry box. If stored outside the original packaging for more than one week, it is recommended to bake at approximately 60°C for at least 20 hours before assembly to remove absorbed moisture and prevent the "popcorn" effect during reflow soldering.

8. Bayanin Aikace-aikace da La'akari da Zane

8.1 Typical Application Circuit

When driven from a voltage source (e.g., a 5V or 3.3V supply rail), each LED chip (green and orange) requires an external current-limiting resistor. The resistor value (R) can be calculated using Ohm's Law: R = (V_Supply- V_F) / I_F. Use the maximum V from the datasheet_Fto ensure the current does not exceed I under worst-case conditions_F(maximum). For example, driving a green LED from a 5V supply with a target I_Fof 20mA: R = (5V - 3.5V) / 0.020A = 75 Ω. A standard 75Ω or 82Ω resistor is suitable. For precise control or multiplexing, a constant current driver is recommended.

8.2 Thermal Management

Despite the low power dissipation (76/75 mW), effective thermal management on the PCB is crucial for maintaining brightness and lifespan, especially under high ambient temperatures or when driven at higher currents. Ensure the PCB layout provides sufficient copper area around the LED pads to act as a heat sink. Avoid placing other heat-generating components nearby.

8.3 Optical Design

The water-clear lens provides a wide, diffused viewing angle. For applications requiring a more directional beam, secondary optics (such as a light pipe or lens) can be mounted above the LED. The bicolor function allows creating a third color (e.g., a yellow hue) by driving both chips simultaneously with adjusted currents, but this requires careful current control to achieve the desired chromaticity.

9. Technical Comparison and Differentiation

LTST-C155TGKFKT distinguishes itself in the market through the following key features:Ultra-thin profile (1.10mm):This is a significant advantage compared to many standard SMD LEDs, enabling its use in ultra-thin devices such as modern smartphones, tablets, and laptops.Dual chips, independent control:Unlike some bicolor LEDs that use a common anode or cathode, this device offers completely independent pins. This provides greater design flexibility, allowing the use of independent drive circuits and more complex signaling patterns without additional multiplexing complexity.Material Technology:The use of InGaN for the green chip and AlInGaP for the orange chip represents efficient semiconductor materials chosen for their respective colors, offering good brightness and color stability.Manufacturing Readiness:Fully compatible with automated placement and standard lead-free reflow profiles, reducing assembly cost and complexity for high-volume manufacturers.

10. Frequently Asked Questions (FAQ)

Q1: Can I drive both the green and orange LEDs simultaneously?A: Yes, the pins are independent. You can drive one, the other, or both simultaneously. Ensure your power supply and circuit can provide the combined current (e.g., up to 50mA if both are 20mA).

Q2: What is the difference between peak wavelength and dominant wavelength?A: Peak wavelength (λ_P) is the physical wavelength at the highest intensity point in the spectrum. Dominant wavelength (λ_d) is a value calculated based on the human eye's color vision (CIE diagram), best matching the perceived color. They are usually close but not identical, especially for broad spectra.

Q3: Why is the reverse voltage rating only 5V?A: LEDs are not designed to block reverse voltage like rectifier diodes. The 5V rating is a safe limit for occasional accidental reverse bias during handling or testing. In circuit design, if connected to AC signals or bidirectional buses, always ensure correct LED polarity or protect it with a series diode.

Q4: How to understand the binning code when ordering?A: The binning code (e.g., green "S", orange "R") specifies the guaranteed minimum and maximum luminous intensity. To ensure consistent brightness across your product line, specify the desired binning code to your distributor. If unspecified, you may receive components from any available bin within the product range.

11. Practical Application Examples

Scenario: Dual-state power indicator for consumer devices.A portable battery-powered device uses this LED to indicate charging status. The design goal is: orange for "charging" and green for "fully charged."Implementation method:The microcontroller (MCU) has two GPIO pins. Each pin is connected to the anode of one LED color via a current-limiting resistor (calculated as described in Section 8.1). The cathodes are connected to ground. The MCU firmware drives the orange LED pin high during charging. When the battery management IC signals a full charge, the MCU turns off the orange pin and drives the green pin high. The ultra-thin package allows it to be mounted behind narrow bezels. The wide viewing angle ensures visibility from all angles. Independent control simplifies the firmware compared to common-anode types that require toggling ground.

12. Introduction to Technical Principles

A light-emitting diode (LED) is a semiconductor device that emits light when current passes through it. This phenomenon is called electroluminescence. When a forward voltage is applied, electrons from the n-type semiconductor and holes from the p-type semiconductor are injected into the active region (junction area). When an electron recombines with a hole, it releases energy in the form of a photon (light particle). The wavelength (color) of the emitted light is determined by the bandgap of the semiconductor material used in the active region.InGaN (Indium Gallium Nitride):This material system has a wider bandgap and can be tuned to emit blue, green, and ultraviolet light. Here, it is designed to emit green light (peak ~525 nm).AlInGaP (Aluminum Indium Gallium Phosphide):This material system is known for its high efficiency in the red, orange, and yellow spectral regions. Here, it is designed to emit orange light (peak ~611 nm).

13. Industry Trends

The development of SMD LEDs like the LTST-C155TGKFKT follows several key industry trends:Miniaturization:The drive towards thinner, smaller components continues to enable slimmer and more compact end products. The 1.10mm height represents this trend.Increased Integration:Combining multiple functions (two colors) in a single package saves PCB space and reduces assembly costs compared to using two separate LEDs.Lead-Free and Green Manufacturing:Compliance with ROHS and compatibility with lead-free, high-temperature reflow profiles are now standard requirements driven by global environmental regulations.Automation Compatibility:Carrier tape and reel packaging, along with design for pick-and-place machines, are crucial for high-volume, cost-effective manufacturing.Performance Standardization:The use of EIA standard packages and JEDEC reflow profiles ensures interoperability and reliability across the electronics supply chain. Future trends may include thinner packages, higher efficiency materials, and the integration of drivers or control logic within the LED package itself.