LTST-C195TGKRKT Dual-Color SMD LED Datasheet - Dimensions 2.0x1.25x0.55mm - Green 3.5V / Red 2.4V - 76mW - Technical Documentation

1. Product Overview

LTST-C195TGKRKT is a dual-color surface-mount device (SMD) LED designed for modern electronic applications, suitable for scenarios with high demands for compact size and reliable performance. The device integrates two different semiconductor chips within a single package: an InGaN chip for emitting green light and an AlInGaP chip for emitting red light. Its primary design goal is to provide a high-brightness, color-indicating solution within an ultra-thin form factor, making it ideal for space-constrained designs such as ultra-thin consumer electronics, wearable devices, and advanced panel indicators.

The core advantage of this LED lies in its ability to achieve dual-color functionality within a single EIA standard package, eliminating the need for two separate components. It is an environmentally friendly product compliant with RoHS standards. The device is supplied in 8mm carrier tape form, wound onto 7-inch diameter reels, fully compatible with high-speed automatic pick-and-place equipment used in mass production. Furthermore, its design can withstand standard infrared (IR) reflow soldering processes, facilitating easy integration into automated PCB assembly lines.

2. In-depth and Objective Interpretation of Technical Parameters

2.1 Absolute Maximum Ratings

These ratings define the stress limits that may cause permanent damage to the device. To ensure reliable operation, operating conditions should not exceed these values. The ratings are specified at an ambient temperature (Ta) of 25°C.

• Power Dissipation (Pd):76 mW for the green chip and 75 mW for the red chip. This parameter indicates the maximum power that the LED can dissipate as heat without performance degradation.
• Peak Forward Current (I_FP):Green is 100 mA, red is 80 mA. This is the maximum allowable pulse current, typically specified at 1/10 duty cycle and 0.1ms pulse width, used for brief, high-intensity flashes.
• DC Forward Current (I_F):Green is 20 mA, red is 30 mA. This is the recommended continuous operating current at standard brightness.
• Temperature Range:Operating Temperature: -20°C to +80°C; Storage Temperature: -30°C to +100°C.
• IR Reflow Conditions:Withstand a peak temperature of 260°C for 10 seconds, which is the standard condition for lead-free (Pb-free) soldering processes.

2.2 Electrical and Optical Characteristics

These are typical performance parameters, measured under the conditions of Ta=25°C and I_F=20mA, sai dai ba wasu bayani.

• Ƙarfin haske (I_V):Kwayar kore mafi ƙarancin ƙima 112 mcd, mafi girma 450 mcd. Kwayar ja mafi ƙarancin ƙima 112 mcd, mafi girma 280 mcd. Ba a ƙayyade ƙimar al'ada ba, yana nuna aikin ana gudanar da shi ta tsarin rarrabawa.
• Kallon kusurwa (2θ_1/2):The typical wide viewing angle for both colors is 130 degrees, defined as the off-axis angle at which the light intensity drops to half of its axial value.
• Peak Wavelength (λ_P):Typical values are 525 nm (green) and 639 nm (red). This is the wavelength corresponding to the highest point in the emission spectrum.
• Dominant Wavelength (λ_d):Typical values are 525 nm (green) and 631 nm (red). This is the single wavelength perceived by the human eye, derived from the CIE chromaticity diagram, and is crucial for color definition.
• Spectral line half-width (Δλ):Typical values are 35 nm (green) and 20 nm (red). This indicates spectral purity; the narrower the half-width, the more saturated and pure the color.
• Forward voltage (V_F):At 20mA, the typical value for green is 3.30V (max 3.50V), and for red is 2.00V (max 2.40V). This is a key parameter for driving circuit design and power supply selection.
• Reverse current (I_R):At a reverse voltage (V_R) of 5V, the maximum for both is 10 µA. The datasheet clearly states that this device is not designed for reverse operation; this test is only for characterizing leakage current characteristics.

3. Grading System Description

This product employs a binning system that classifies LEDs based on key optical parameters to ensure consistency within each batch. The tolerance for each luminous intensity bin is ±15%, and the tolerance for the dominant wavelength bin is ±1 nm.

3.1 Luminous Intensity Binning

Green (@20mA):
Grade Code R: 112.0 – 180.0 mcd
Grade Code S: 180.0 – 280.0 mcd
Grade Code T: 280.0 – 450.0 mcd

Red (@20mA):
Grade Code R: 112.0 – 180.0 mcd
Grade Code S: 180.0 – 280.0 mcd

3.2 Dominant Wavelength Binning (Green Only)

Bin Code AP: 520.0 – 525.0 nm
Gear code AQ: 525.0 – 530.0 nm
Gear code AR: 530.0 – 535.0 nm

4. Performance Curve Analysis

Although specific graphical curves are referenced in the datasheet (e.g., Figure 1 for spectral distribution, Figure 6 for viewing angle), their typical interpretation is crucial for design.

• IV curve:Forward voltage (V_F) and forward current (I_FThe relationship is nonlinear. For both chips, V_Fwill increase with I_Fand decrease with rising junction temperature. It is strongly recommended to use a constant current driver rather than a constant voltage source to ensure stable light output.
• Temperature Characteristics:The luminous intensity typically decreases as the junction temperature increases. The operating temperature range of -20°C to +80°C defines the environmental conditions under which the specified performance is guaranteed. Designers must consider thermal management on the PCB to prevent excessive temperature rise under high current or in confined spaces.
• Spectral Distribution:Compared to red (AlInGaP) chips (20nm), green (InGaN) chips have a broader spectral half-width (35nm). This affects color mixing when used with other LEDs and impacts the perceived color saturation.

5. Mechanical and Packaging Information

5.1 Package Dimensions

This device conforms to the EIA standard package outline. Key dimensions include a body size of approximately 2.0mm x 1.25mm and a critical low-profile height of 0.55mm (typical). Unless otherwise specified, all dimensional tolerances are ±0.10mm. The package employs a water-clear lens, which is optimal for achieving the specified wide viewing angle and maintaining pure emission color.

5.2 Pin Assignment and Polarity

This LED has four terminals. The green chip is connected between pins 1 and 3. The red chip is connected between pins 2 and 4. This configuration allows for independent control of each color. The cathode/anode designation for each chip must be verified against the recommended pad layout diagram to ensure correct orientation during PCB design and assembly.

5.3 Recommended Pad Dimensions

The datasheet provides recommended pad patterns (footprints) for PCB design. Adhering to these dimensions is crucial for achieving reliable solder joints, proper alignment, and effective heat dissipation during reflow. Pad design also helps prevent "tombstoning" (component lifting on one end) during the soldering process.

6. Soldering and Assembly Guide

6.1 Reflow Soldering Temperature Profile

Provides recommended IR reflow temperature profile for lead-free process. Key parameters include:
- Preheating:150°C to 200°C.
- Preheating time:Up to 120 seconds, to gradually heat the circuit board and components, activate the flux, and minimize thermal shock.
- Peak temperature:Maximum 260°C.
- Time Above Liquidus:The component should not be exposed to the peak temperature for more than 10 seconds, and this reflow cycle should not be performed more than twice.

The curve is based on JEDEC standards to ensure reliability. However, the datasheet correctly points out that the optimal profile depends on the specific board design, components, solder paste, and oven, so characterization is recommended.

6.2 Manual Soldering

If hand soldering must be performed, use a soldering iron with a temperature not exceeding 300°C and limit the contact time per solder joint to a maximum of 3 seconds. This operation should be performed only once to avoid thermal damage to the LED chip and plastic package.

6.3 Storage Conditions

LED is a Moisture Sensitive Device (MSD).
- Sealed Package:Store at ≤ 30°C and ≤ 90% RH. Use within one year from the date the moisture barrier bag is opened.
- Opened packaging:Store at ≤ 30°C and ≤ 60% RH. It is recommended to complete IR reflow soldering within one week after opening. For long-term storage outside the original packaging, use a sealed container with desiccant or a nitrogen dry cabinet. Components stored for more than one week should be baked at approximately 60°C for at least 20 hours prior to soldering to remove absorbed moisture and prevent "popcorn" effect (package cracking due to vapor pressure during reflow).

6.4 Cleaning

Use only the specified cleaning agents. Unspecified chemicals may damage the plastic package. If cleaning is required after soldering, immerse the LED in ethanol or isopropyl alcohol at room temperature for no more than one minute. Do not use ultrasonic cleaning unless its compatibility has been verified, as it may cause mechanical stress.

7. Packaging and Ordering Information

7.1 Carrier Tape and Reel Specifications

The device is supplied in embossed carrier tape with protective cover tape, wound on 7-inch (178mm) diameter reels. The standard reel quantity is 4000 units. For remainder quantities, the minimum packaging quantity is 500 units. The packaging conforms to the ANSI/EIA 481-1-A-1994 specification. A maximum of two consecutive missing components (pockets) is allowed per reel.

7.2 Part Number Interpretation

The part number LTST-C195TGKRKT follows the manufacturer's internal coding system, which typically encodes information related to series, size, color, bin code, and packaging. In this case, "TG" and "KR" may represent the color/bin combination for green and red, respectively.

8. Application Suggestions

8.1 Typical Application Scenarios

• Status Indicator Light:Bicolor function allows a single component point to emit multiple status signals (e.g., green=normal/on, red=fault/alarm, bicolor=standby/warning).
• Keyboard and icon backlight:Its ultra-thin profile is ideal for backlighting slim buttons or symbols in consumer electronics, home appliances, and automotive interiors.
• Panel mount indicator:Suitable for industrial control panels, network equipment, and instrumentation where space is limited and clear color differentiation is required.
• Portable and Wearable Devices:Smartwatches, fitness trackers, and medical monitors benefit from their low profile and dual-function indicator lights.

8.2 Design Considerations

• Current Limiting:Always use a series current-limiting resistor or constant-current driver for each color channel. Based on the power supply voltage (V_CC), the typical V of LED at the required current_Fand the required I_F(e.g., 20mA) to calculate the resistance value. Green example: R = (V_CC- 3.3V) / 0.020A.
• ESD Protection:LEDs are sensitive to Electrostatic Discharge (ESD). If the trace length is long or the environment is prone to ESD, implement ESD protection measures (e.g., TVS diode) on the PCB near the LED connection points. Always handle components with proper ESD precautions (wrist strap, grounded workstation).
• Thermal Management:Although power consumption is low, ensure sufficient copper area around the thermal pad (if present) or pins to conduct heat, especially when operating at high ambient temperatures or near maximum current.
• Optical Design:The water-clear lens and 130-degree viewing angle provide wide diffused light. For directional light, an external lens or light guide may be required.

9. Technical Comparison and Differentiation

The primary differentiation of LTST-C195TGKRKT lies in its functional combination:
1. Ultra-thin profile (0.55mm):Thinner than many standard bi-color LEDs, suitable for increasingly slim product designs.
2. Chip technology:Using efficient InGaN for green and AlInGaP for red, providing excellent brightness and color performance.
3. Dual-chip integration:Combining two colors within an industry-standard package size, saving PCB space and assembly costs compared to using two separate LEDs.
4. Manufacturing Compatibility:Fully compatible with tape and reel, automated placement, and lead-free IR reflow processes, making it ideal for high-volume automated production.

10. Frequently Asked Questions (Based on Technical Parameters)

Q1: Can I drive the green and red LEDs simultaneously at their maximum DC current?
A: The absolute maximum ratings specify the power dissipation per chip (76mW for green, 75mW for red). Operating simultaneously at 20mA (green) and 30mA (red) results in power dissipation of approximately 66mW (3.3V*0.02A) and 60mW (2.0V*0.03A) respectively, both within limits. However, the total heat generated within the small package must be considered, and derating may be necessary at high ambient temperatures.

Q2: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λ_P) is the physical wavelength corresponding to the highest intensity point in the emission spectrum. Dominant wavelength (λ_d) is a value calculated based on human color vision (CIE diagram), representing the "color" we perceive. For monochromatic LEDs, they are usually very close, but for broader spectra (like the green chip here), they may differ slightly. λ_dis more relevant for color specification.

Q3: If the device is not intended for reverse operation, why is the reverse current test conducted at 5V?
A: The I_Rtest performed at V_R=5V is a quality and leakage current test for the semiconductor junction. It verifies the integrity of the chip. Applying reverse voltage in an actual circuit is not recommended, as it is not designed to block significant reverse voltage, and doing so may rapidly damage the LED.

Q4: Yaya za a zaɓi lambar matakin da ya dace don aikace-aikacena?
A: Don aikace-aikacen da ke buƙatar kiyaye daidaiton haske tsakanin raka'a da yawa (misali, fitilun hali akan panel), ƙayyade matakin ƙarfin haske mai tsauri (misali, matakin S ko T). Don aikace-aikacen da ke da buƙatu masu tsauri game da launi (misali, haɗa launuka), ƙayyade matakin babban tsayin raƙuman ruwa (misali, AP, AQ, AR don kore). Yi shawara tare da mai kaya lokacin siyayya, don tabbatar da cewa kayan da aka kawo sun dace da buƙatun rarrabawar ku.

11. Practical Use Cases

Scenario: Designing a Dual-State Indicator Light for an IoT Sensor Module
Due to space constraints, a compact IoT sensor module requires a single LED to indicate power (green) and data transmission activity (red). The LTST-C195TGKRKT was selected.
1. PCB Layout:Yi amfani da zane-zanen filaye da aka ba da shawara. Filaye 1 da 3 (kore) suna haɗawa da filin GPIO ta hanyar resistor 100Ω, wanda aka saita don fitar da sigina mai girma don nuna "Kunna" (don wutar lantarki 3.3V: (3.3V-3.3V)/0.02A ≈ 0Ω, don haka ana amfani da ƙaramin resistor don iyakance ƙarfin kwarara). Filaye 2 da 4 (ja) suna haɗawa da wani filin GPIO ta hanyar resistor 68Ω (don wutar lantarki 3.3V: (3.3V-2.0V)/0.02A = 65Ω).
2. Firmware:Lokacin da wutar lantarki ta kasance daidai, LED kore yana ci gaba da haskakawa. LED ja yana ƙyalli a takaice yayin lokacin fakitin canja bayanai.
3. Sakamako:This module provides clear dual-state indication from a 2.0x1.25mm point, occupying minimal board space and height, and is assembled using standard SMT processes.

12. Introduction to Principles

Light emission in an LED is based on the electroluminescence of a semiconductor p-n junction. When a forward voltage is applied, electrons from the n-type region and holes from the p-type region are injected into the active region. When these carriers recombine, they release energy in the form of photons (light). The specific wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor material used in the active region.
-Green LEDUseInGaN(InGaN) compound semiconductor. Adjusting the ratio of indium to gallium can tune the bandgap to produce green light (approximately 525 nm).
-Red LEDUseAlInGaP(AlInGaP) compound semiconductor. This material system efficiently generates red, orange, and amber light. Here, it is tuned to emit red light (approximately 631-639 nm).
Both chips are encapsulated in a single plastic package with a water-clear epoxy lens, which protects the chips, provides mechanical stability, and shapes the light output pattern.

13. Development Trends

The SMD LED market, such as for components like the LTST-C195TGKRKT, continues to evolve, driven by several key trends:
1. Miniaturization:The demand for thinner and smaller components persists, driving package heights below 0.5mm and smaller package sizes.
2. Increased Integration:Baya ga launi biyu, abubuwan da ke faruwa sun haɗa da haɗa RGB (guntu uku) ko RGBW (guntu uku + fari) a cikin ɗaukar hoto guda ɗaya, har ma da haɗa IC tuƙi a cikin ɗaukar hoto na LED ("LED mai hankali").
3. Ingantacciyar inganci da haske:Ci gaba da haɓaka girma da ƙirar guntun ya kawo mafi girman ingancin haske (ƙarin fitar haske a kowace watt na lantarki), yana ba da damar yin amfani da ƙarancin wutar lantarki ko mafi girman haske a ƙarashin wutar lantarki iri ɗaya.
4. Ingantaccen aminci da aikin zafi:Advancements in packaging materials (molding compounds, leadframes) have enhanced resistance to humidity, high temperatures, and thermal cycling, extending operational lifespan, particularly in automotive and industrial applications.
5. Color Consistency and Advanced Binning:Tighter binning tolerances for luminous flux, chromaticity coordinates (x, y on the CIE diagram), and forward voltage are becoming standard requirements for applications such as display backlighting and architectural lighting, driving the need for more sophisticated production testing and sorting.