LTST-C193KGKT-2A Chip LED Datasheet - Dimensions 1.6x0.8x0.35mm - Voltage 1.6-2.2V - Green Color - English Technical Document

1. Product Overview

The LTST-C193KGKT-2A is a surface-mount device (SMD) chip LED designed for modern, space-constrained electronic applications. Its primary function is to provide a reliable and bright green light source. The core advantage of this component lies in its exceptionally thin profile of only 0.35mm, making it suitable for applications where vertical space is at a premium, such as in ultra-slim displays, mobile devices, and wearable technology. It utilizes an AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material for the light-emitting region, which is known for producing high-efficiency light in the green to amber spectrum. The device is packaged on industry-standard 8mm tape on 7-inch reels, ensuring compatibility with high-speed automated pick-and-place assembly equipment. It is classified as a green product and complies with RoHS (Restriction of Hazardous Substances) directives.

2. Technical Parameters Deep Objective Interpretation

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation at or beyond these limits is not guaranteed.

• 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 can lead to overheating and reduced lifespan.
• DC Forward Current (IF): 30 mA. The maximum continuous current that can be applied to the LED.
• Peak Forward Current: 80 mA, but only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). This allows for brief periods of higher brightness without thermal damage.
• Derating: The maximum forward current must be linearly reduced by 0.4 mA for every degree Celsius the ambient temperature rises above 25°C. This is crucial for thermal management in high-temperature environments.
• Reverse Voltage (VR): 5 V. Applying a reverse voltage higher than this can cause immediate and catastrophic failure of the LED junction.
• Operating & Storage Temperature Range: -55°C to +85°C. The device is rated for operation and storage within this wide industrial temperature range.
• Soldering Temperature Tolerance: The LED can withstand wave or infrared reflow soldering at 260°C for up to 5 seconds, and vapor phase soldering at 215°C for up to 3 minutes. This defines its compatibility with common PCB assembly processes.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters measured at Ta=25°C and a standard test current (IF) of 2mA, unless otherwise noted.

• Luminous Intensity (Iv): Ranges from a minimum of 1.80 mcd to a maximum of 11.2 mcd. The actual value for a specific unit depends on its assigned bin code (see Section 3). Intensity is measured with a filter approximating the photopic (human eye) response curve.
• Viewing Angle (2θ1/2): 130 degrees. This is a very wide viewing angle, meaning the emitted light is dispersed over a broad area rather than being a narrow beam. The angle is defined as the point where the luminous intensity drops to half of its value directly on-axis (0 degrees).
• Peak Emission Wavelength (λP): 574 nm. This is the specific wavelength at which the LED emits the most optical power.
• Dominant Wavelength (λd): Ranges from 564.5 nm to 573.5 nm. This is the single wavelength perceived by the human eye that defines the color (green, in this case). It is derived from the full spectral output and the CIE chromaticity diagram. Specific bins are defined within this range.
• Spectral Line Half-Width (Δλ): 15 nm. This indicates the spectral purity or bandwidth of the emitted light. A smaller value would indicate a more monochromatic (pure color) source.
• Forward Voltage (VF): Ranges from 1.60 V to 2.20 V at IF=2mA. This is the voltage drop across the LED when it is conducting current. It is a critical parameter for designing the current-limiting circuitry.
• Reverse Current (IR): Maximum 10 μA at VR=5V. This is the small leakage current that flows when the LED is reverse-biased within its maximum rating.
• Capacitance (C): 40 pF measured at 0V bias and 1 MHz. This parasitic capacitance can be relevant in high-frequency switching applications.
• Electrostatic Discharge (ESD) Threshold (HBM): 1000 V (Human Body Model). This indicates a moderate level of ESD sensitivity. Proper ESD handling procedures are mandatory to prevent latent or immediate damage.

3. Binning System Explanation

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

3.1 Luminous Intensity Binning

Units are categorized into four bins (G, H, J, K) based on their luminous intensity measured at 2mA. Each bin has a minimum and maximum value, with a +/-15% tolerance on each intensity bin.

• Bin G: 1.80 - 2.80 mcd
• Bin H: 2.80 - 4.50 mcd
• Bin J: 4.50 - 7.10 mcd
• Bin K: 7.10 - 11.20 mcd

3.2 Dominant Wavelength Binning

Units are also binned into three groups (B, C, D) based on their dominant wavelength, which defines the precise shade of green. Tolerance for each bin is +/- 1 nm.

• Bin B: 564.5 - 567.5 nm
• Bin C: 567.5 - 570.5 nm
• Bin D: 570.5 - 573.5 nm

The full part number (e.g., LTST-C193KGKT-2A) incorporates these bin codes, allowing for precise selection. The \"K\" indicates the intensity bin and the following letter (implicit in the datasheet example) would indicate the wavelength bin.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (Fig.1, Fig.6), their typical behavior can be described based on the technology.

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

An AlInGaP LED exhibits a characteristic I-V curve with a forward voltage (VF) in the range of 1.6-2.2V at low current (2mA). As the forward current increases, VF increases logarithmically. This non-linear relationship is why LEDs must be driven by a current source or with a series current-limiting resistor, not a constant voltage source.

4.2 Luminous Intensity vs. Forward Current

The light output (luminous intensity) is approximately proportional to the forward current over a significant operating range. However, at very high currents, efficiency drops due to increased heat generation (droop effect). The rated DC current of 30mA defines a safe operating point for maintaining efficiency and longevity.

4.3 Temperature Characteristics

The forward voltage (VF) of an LED has a negative temperature coefficient, meaning it decreases as the junction temperature increases. Conversely, the luminous intensity and dominant wavelength also shift with temperature; typically, intensity decreases and the wavelength may increase slightly (red-shift) as temperature rises. The derating specification (0.4 mA/°C) is a direct result of the need to manage these thermal effects.

5. Mechanical & Packaging Information

5.1 Package Dimensions

The LED has an EIA standard chip package form factor. Key dimensions include a length of 1.6mm, a width of 0.8mm, and the critical height of 0.35mm. All dimensional tolerances are typically ±0.10mm unless otherwise specified. The package features a water-clear lens, which does not alter the color of the underlying AlInGaP chip, allowing the native green light to pass through.

5.2 Polarity Identification & Pad Design

The datasheet includes a suggested soldering pad layout (land pattern) for PCB design. Adhering to this pattern is essential for achieving reliable solder joints and proper alignment during reflow. The LED itself has anode and cathode markings (typically a notch, bevel, or dot near the cathode). Correct polarity must be observed during assembly, as reverse connection will prevent operation and may damage the device if the reverse voltage rating is exceeded.

5.3 Tape and Reel Packaging

The components are supplied on 8mm wide embossed carrier tape wound onto 7-inch (178mm) diameter reels. Each reel contains 5000 pieces. The packaging conforms to ANSI/EIA 481-1-A-1994 standards, ensuring compatibility with automated feeders. The tape has a cover seal to protect components from contamination. Specifications allow for a maximum of two consecutive missing components and a minimum packing quantity of 500 pieces for remainder reels.

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Profiles

The datasheet provides suggested infrared (IR) reflow profiles for both normal (tin-lead) and lead-free (SnAgCu) solder processes. Key parameters include:

• Preheat: A gradual ramp to a soak temperature (e.g., 120-150°C) to activate flux and minimize thermal shock.
• Peak Temperature: Not to exceed 260°C. The time above liquidus (for lead-free solder, ~217°C) and the time at peak temperature must be controlled to prevent damage to the LED's plastic package and internal wire bonds. The recommendation is a maximum of 5 seconds at 260°C.
• Cooling Rate: A controlled cool-down phase is also important for joint reliability.

6.2 Wave Soldering & Hand Soldering

For wave soldering, a preheat of up to 100°C for 60 seconds max is suggested, with the solder wave at a maximum of 260°C for up to 10 seconds. For manual repair with a soldering iron, the tip temperature should not exceed 300°C, and contact time should be limited to 3 seconds per joint, for one time only, to prevent excessive heat transfer.

6.3 Cleaning

If cleaning after soldering is necessary, only specified alcohol-based solvents like ethyl alcohol or isopropyl alcohol should be used. The LED should be immersed at normal temperature for less than one minute. Unspecified chemical cleaners may damage the epoxy lens or package material.

6.4 Storage & Handling

LEDs should be stored in an environment not exceeding 30°C and 70% relative humidity. Once removed from their original moisture-barrier bag, components should be reflow-soldered within 672 hours (28 days) to avoid moisture absorption, which can cause \"popcorning\" during reflow. For longer storage outside the original bag, they must be kept in a sealed container with desiccant or in a nitrogen ambient. If stored for more than 672 hours, a bake at 60°C for at least 24 hours is required before assembly to drive out moisture.

7. Application Suggestions

7.1 Typical Application Scenarios

This ultra-thin, bright green LED is ideal for:

• Status Indicators: Power, connectivity, or mode indicators in consumer electronics (smartphones, tablets, laptops, wearables).
• Backlighting: Edge-lighting for very thin display panels or keypad illumination.
• Automotive Interior Lighting: Dashboard indicators, switch backlighting (where space is limited).
• Industrial Control Panels: Status and fault indicators on control units and human-machine interfaces (HMIs).

7.2 Design Considerations

• Current Drive: LEDs are current-driven devices. To ensure uniform brightness when using multiple LEDs in parallel, a separate current-limiting resistor must be used in series with each LED (Circuit Model A). Connecting LEDs directly in parallel (Circuit Model B) is not recommended due to variations in their forward voltage (VF), which will cause uneven current sharing and thus uneven brightness.
• Thermal Management: Even with its low power, proper PCB layout to dissipate heat is important, especially when operating near maximum ratings or in high ambient temperatures. Follow the current derating curve.
• ESD Protection: Implement ESD protection measures in the circuit if the LED is in an exposed location (e.g., a front-panel indicator). Always follow ESD-safe handling procedures during assembly: use grounded wrist straps, anti-static mats, and properly grounded equipment.

8. Technical Comparison & Differentiation

The primary differentiating factors of the LTST-C193KGKT-2A are its 0.35mm height and AlInGaP technology. Compared to older technologies like standard GaP (Gallium Phosphide) green LEDs, AlInGaP offers significantly higher luminous efficiency, resulting in brighter output for the same drive current. The ultra-thin profile is a key advantage over many standard chip LEDs (which are often 0.6mm or taller), enabling design in next-generation slim devices. Its compatibility with lead-free, high-temperature reflow processes also makes it suitable for modern, RoHS-compliant manufacturing lines.

9. Frequently Asked Questions (Based on Technical Parameters)

Q1: Can I drive this LED directly from a 3.3V or 5V logic supply?
A: No. You must use a series resistor to limit the current. For example, with a 3.3V supply and a typical VF of 1.9V at 2mA, the required resistor value is R = (3.3V - 1.9V) / 0.002A = 700 Ohms. Always calculate based on the maximum VF to ensure the current does not exceed the desired value.

Q2: Why is there such a wide range in luminous intensity (1.8 to 11.2 mcd)?
A: This is the total production spread. The binning system (G, H, J, K) allows you to select a specific, narrower brightness range for your application to ensure consistency across all units in your product.

Q3: Is this LED suitable for outdoor use?
A: The operating temperature range (-55°C to +85°C) supports many outdoor environments. However, the plastic package may be susceptible to UV degradation and moisture ingress over very long periods. For harsh outdoor applications, LEDs with specifically qualified outdoor packages should be considered.

Q4: What happens if I exceed the 5V reverse voltage?
A: The LED junction will likely experience avalanche breakdown, causing immediate and permanent failure (open or short circuit). Always ensure the circuit design prevents reverse biasing beyond this rating.

10. Practical Design Case

Scenario: Designing a status indicator for a battery-powered IoT sensor module. The indicator must be very small, low power, and clearly visible. A green LED is chosen for \"active/normal\" status.

Implementation:
1. Component Selection: The LTST-C193KGKT-2A is chosen for its 0.35mm height and good brightness at low current.
2. Circuit Design: The module uses a 3.0V coin cell battery. To conserve power, a drive current of 2mA is selected. Using the maximum VF of 2.20V for a conservative design: R = (3.0V - 2.20V) / 0.002A = 400 Ohms. A standard 390 Ohm resistor is used.
3. PCB Layout: The recommended solder pad dimensions from the datasheet are used. The LED is placed near the edge of the board for visibility. A small ground pour under the LED is avoided to prevent solder wicking issues during reflow.
4. Result: The indicator provides adequate brightness with minimal power draw (approx. 6mW total for LED and resistor), and the ultra-thin package fits within the device's slim enclosure.

11. Principle Introduction

Light emission in an AlInGaP LED is based on electroluminescence in 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 (the quantum well). When an electron recombines with a hole, energy is released in the form of a photon. The specific wavelength (color) of this photon is determined by the bandgap energy of the AlInGaP alloy composition used in the active region. A wider bandgap produces shorter wavelength (bluer) light; the specific alloy for this LED is engineered to produce green light with a peak around 574 nm. The water-clear epoxy lens encapsulates the chip, provides mechanical protection, and helps shape the light output into the wide 130-degree viewing angle.

12. Development Trends

The trend in chip LEDs for consumer and industrial electronics continues toward:
1. Increased Efficiency (lm/W): Ongoing material science improvements in AlInGaP and InGaN (for blue/white) technologies push for more light output per unit of electrical input, reducing power consumption and heat generation.
2. Miniaturization: The drive for thinner and smaller devices demands LEDs with ever-reduced footprints (XY dimensions) and, critically, heights (Z dimension). The 0.35mm height of this LED represents this trend.
3. Improved Color Consistency & Binning: Tighter binning tolerances for wavelength and intensity are becoming standard, allowing for more uniform visual appearance in applications using multiple LEDs.
4. Enhanced Reliability: Improvements in package materials (epoxy, silicone) to withstand higher temperature reflow profiles (for lead-free assembly) and harsher environmental conditions.
5. Integration: While discrete LEDs remain vital, there is a parallel trend toward integrated LED modules with built-in drivers, controllers, and multiple colors in a single package for smart lighting applications.