LTST-C193TGKT SMD LED Datasheet - Dimensions 3.2x1.6x0.4mm - Voltage 2.8-3.6V - Color Green - Power 76mW - English Technical Documentation

1. Product Overview

The LTST-C193TGKT is a surface-mount device (SMD) chip LED designed for modern, space-constrained electronic applications. It belongs to a family of extra-thin LEDs, featuring a remarkably low profile of just 0.4mm in height. This makes it an ideal choice for backlighting indicators, status lights, and decorative illumination in slim consumer electronics, automotive interiors, and portable devices where vertical clearance is limited.

The LED emits a green light using an InGaN (Indium Gallium Nitride) semiconductor material, known for its high efficiency and brightness. The package features a water-clear lens, which does not diffuse the light, resulting in a more focused and intense luminous output from the chip itself. It is compliant with RoHS (Restriction of Hazardous Substances) directives, classifying it as a green product.

2. Technical Parameters Deep Objective Interpretation

2.1 Photometric and Optical Characteristics

The key optical parameters are measured at a standard ambient temperature (Ta) of 25°C and a forward current (IF) of 20mA, which is the recommended continuous operating current.

• Luminous Intensity (Iv): Ranges from a minimum of 112.0 millicandelas (mcd) to a maximum of 450.0 mcd. The typical value falls within this range. Intensity is measured using a sensor filtered to match the human eye's photopic response (CIE curve).
• Viewing Angle (2θ_1/2): This LED has a very wide viewing angle of 130 degrees. The angle θ_1/2 is defined as the off-axis angle where the luminous intensity drops to half of its value measured on the central axis (0°).
• Peak Wavelength (λ_P): The wavelength at which the emitted optical power is maximum, typically 525 nm for this device.
• Dominant Wavelength (λ_d): A more perceptually relevant measure of color, derived from the CIE chromaticity diagram. It specifies the single wavelength that best represents the perceived color. For the LTST-C193TGKT, it ranges from 520.0 nm to 535.0 nm.
• Spectral Line Half-Width (Δλ): Measures the spectral purity of the light source. It is the width of the emission spectrum at half of its maximum power. A value of 35 nm is typical for this green InGaN LED.

2.2 Electrical Characteristics

• Forward Voltage (V_F): When driven at 20mA, the voltage drop across the LED anode and cathode ranges from 2.80V (Min) to 3.60V (Max). This parameter is critical for driver circuit design and power dissipation calculations.
• Reverse Current (I_R): With a reverse bias of 5V applied, the leakage current is a maximum of 10 µA. It is crucial to note that this LED is not designed for operation under reverse voltage; this test condition is for characterization only.

2.3 Absolute Maximum Ratings and Thermal Characteristics

These ratings define the limits beyond which permanent damage to the device may occur. They are not intended for normal operation.

• Power Dissipation (P_d): The maximum allowable power the package can dissipate is 76 mW at 25°C ambient.
• Forward Current: The maximum continuous DC forward current is 20 mA. A higher peak forward current of 100 mA is permissible only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width).
• Temperature Ranges: The device can operate in ambient temperatures from -20°C to +80°C. For storage, the range is wider: -30°C to +100°C.
• Soldering Thermal Limit: The LED can withstand infrared reflow soldering with a peak temperature of 260°C for a maximum of 10 seconds, which aligns with common lead-free (Pb-free) assembly processes.

3. Binning System Explanation

To ensure consistency in mass production, LEDs are sorted into performance bins based on key parameters. The LTST-C193TGKT uses a three-dimensional binning system.

3.1 Forward Voltage Binning

Units are sorted by their forward voltage (V_F) at 20mA into four bins (D7 to D10), each with a 0.2V range and a ±0.1V tolerance. This allows designers to select LEDs with tighter voltage matching for applications requiring uniform current sharing in parallel configurations.

3.2 Luminous Intensity Binning

LEDs are binned for brightness into three categories (R, S, T) with a ±15% tolerance on each bin's range. Bin 'T' represents the highest intensity group (280-450 mcd). This binning is essential for applications requiring consistent brightness levels across multiple indicators.

3.3 Dominant Wavelength Binning

The color (hue) is controlled by binning the dominant wavelength into three groups (AP, AQ, AR), each spanning 5 nm with a ±1 nm tolerance. This ensures a consistent green color appearance across all units in a production batch.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet, their implications are standard for LED technology.

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

The relationship is exponential, typical of a diode. A small increase in voltage beyond the turn-on threshold causes a large increase in current. Therefore, LEDs must be driven by a current-limited source, not a constant voltage source, to prevent thermal runaway and destruction.

4.2 Luminous Intensity vs. Forward Current

The light output is approximately proportional to the forward current up to the rated maximum. Operating above 20mA may increase brightness but will reduce lifetime and reliability due to increased junction temperature.

4.3 Temperature Dependence

LED performance is temperature-sensitive. As the junction temperature increases:

• Forward Voltage (V_F): Decreases slightly.
• Luminous Intensity (Iv): Decreases. The efficiency drops as temperature rises.
• Dominant Wavelength (λ_d): May shift slightly, potentially causing a subtle color change.

Proper thermal management on the PCB (e.g., via thermal relief pads) is crucial for maintaining performance and longevity.

5. Mechanical and Package Information

5.1 Package Dimensions

The LED conforms to an EIA standard chip LED package footprint. Key dimensions include a body size of approximately 3.2mm x 1.6mm, with the defining feature being the ultra-low height of 0.4mm. Detailed dimensional drawings with tolerances of ±0.10mm are provided for PCB layout.

5.2 Pad Layout and Polarity Identification

The datasheet includes suggested solder pad dimensions to ensure reliable soldering and proper alignment. The LED is polarized. The anode (+) and cathode (-) terminals are typically marked on the package or indicated in the footprint diagram. Correct orientation is essential for circuit operation.

5.3 Tape and Reel Packaging

The product is supplied in industry-standard 8mm carrier tape on 7-inch (178mm) diameter reels. Each reel contains 5000 pieces. The packaging follows ANSI/EIA 481-1-A-1994 specifications, ensuring compatibility with automated pick-and-place equipment, which is critical for high-volume manufacturing.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A suggested infrared (IR) reflow profile for lead-free processes is provided. Key parameters include:

• Pre-heat: 150°C to 200°C for a maximum of 120 seconds to gradually heat the board and components, minimizing thermal shock.
• Peak Temperature: Maximum of 260°C.
• Time Above Liquidus: The time the solder is molten should be controlled.
• Critical Limit: The component body temperature must not exceed 260°C for more than 10 seconds.

The profile is based on JEDEC standards, ensuring reliability.

6.2 Hand Soldering

If manual soldering is necessary, use a temperature-controlled iron set to a maximum of 300°C. The soldering time per lead should not exceed 3 seconds, and it should be performed only once to avoid thermal damage to the plastic package and the semiconductor die.

6.3 Cleaning

If post-solder cleaning is required, 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 package material.

6.4 Storage and Handling

• ESD (Electrostatic Discharge) Sensitivity: LEDs are susceptible to damage from static electricity. Proper ESD precautions (wrist straps, grounded workstations, conductive foam) are mandatory during handling.
• Moisture Sensitivity: As a surface-mount device, it has a moisture sensitivity level (implied). If the original sealed moisture-barrier bag is opened, the LEDs should be used within 672 hours (28 days) or baked before reflow to prevent "popcorning" during soldering.
• Storage Conditions: For long-term storage in opened packaging, use a sealed container with desiccant or a nitrogen atmosphere.

7. Application Suggestions

7.1 Typical Application Scenarios

• Status Indicators: Power-on, battery charging, network activity lights in smartphones, tablets, laptops, and wearables.
• Backlighting: Illumination for membrane switches, small LCD displays, or logos in thin consumer products.
• Decorative Lighting: Accent lighting in automotive dashboards, interior trim, or home appliances.
• Panel Indicators: On industrial control panels, medical devices, and communication equipment where space is premium.

7.2 Design Considerations

• Current Driving: Always use a series current-limiting resistor or a dedicated constant-current LED driver IC. Calculate the resistor value using R = (V_supply - V_F) / I_F, using the maximum V_F from the datasheet to ensure current does not exceed 20mA under worst-case conditions.
• Thermal Management: Although small, power dissipation (up to 72mW at 20mA, 3.6V) generates heat. Ensure the PCB layout provides adequate copper area around the solder pads to act as a heat sink, especially if multiple LEDs are used or ambient temperatures are high.
• Optical Design: The water-clear lens produces a narrow, intense beam. For wider or diffused illumination, external lenses or light guides may be necessary.
• Binning Selection: For applications requiring color or brightness uniformity, specify the required bin codes (V_F, I_v, λ_d) when ordering.

8. Technical Comparison and Differentiation

The primary differentiating factor of the LTST-C193TGKT is its 0.4mm ultra-thin profile. Compared to standard chip LEDs which are often 0.6mm or 0.8mm tall, this 33-50% reduction in height is significant for modern ultra-slim device designs. Its wide 130-degree viewing angle is also an advantage over narrower-angle LEDs when off-axis visibility is important. The combination of InGaN technology (for green emission), RoHS compliance, and compatibility with standard Pb-free reflow processes makes it a versatile and future-proof component for global electronics manufacturing.

9. Frequently Asked Questions (Based on Technical Parameters)

9.1 Can I drive this LED with a 3.3V supply without a resistor?

No, this is not recommended and is likely to destroy the LED. The forward voltage ranges from 2.8V to 3.6V. If you connect a 3.3V supply directly to an LED with a V_F of 2.9V, the voltage difference (0.4V) will cause a very high, uncontrolled current to flow, far exceeding the 20mA maximum. A series resistor is always required for simple DC drive.

9.2 Why is there a peak current rating (100mA) higher than the DC current rating (20mA)?

The semiconductor junction can handle short, high-current pulses without overheating because the thermal time constant of the tiny die is very short. The 100mA rating at a 1/10 duty cycle allows for brief pulses of higher brightness (e.g., in multiplexed displays or for signaling) while keeping the average power and temperature within safe limits. Continuous operation must not exceed 20mA.

9.3 What does "water clear" lens mean for the light output?

A "water clear" or non-diffused lens means the epoxy encapsulant is transparent. This results in the highest possible light output from the package because no light is scattered by diffusion particles. The beam pattern will be more defined by the shape of the LED chip and the reflector cup, often appearing as a bright, small spot when viewed head-on.

9.4 How do I interpret the bin codes when ordering?

For consistent results in your application, you should specify the desired bin codes for Voltage (V_F), Intensity (I_v), and Dominant Wavelength (λ_d). For example, requesting bins D8 (3.0-3.2V), S (180-280 mcd), and AQ (525-530 nm) will give you LEDs with mid-range voltage, medium-high brightness, and a specific shade of green. If not specified, you will receive a mix from production.

10. Practical Design and Usage Case

Case: Designing a Status Indicator for a Slim Bluetooth Speaker

A designer is creating a compact Bluetooth speaker with an aluminum casing only 5mm thick. A multi-color status LED is needed to indicate power, pairing, and battery level. Space behind the front grille is extremely limited.

Solution: The LTST-C193TGKT (green) is selected alongside similar red and blue ultra-thin LEDs. Their 0.4mm height allows them to fit perfectly within the constrained internal space. The designer:

1. Places the LEDs on the main PCB close to the grille.
2. Uses a microcontroller GPIO pin for each color, with a 100Ω series resistor calculated for a 3.3V system (assuming max V_F of 3.6V gives a safe current of ~10mA).
3. Specifies the same intensity bin (e.g., 'S') for all three colors to ensure balanced brightness.
4. Includes a small copper pour under the LED pads on the PCB for slight heat spreading.
5. Follows the recommended reflow profile during assembly to ensure reliability.

The result is a bright, uniform status indicator that fits the sleek industrial design without mechanical compromise.

11. Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light through electroluminescence. When a forward voltage is applied across the p-n junction, electrons from the n-type material recombine with holes from the p-type material in the active region. This recombination releases energy in the form of photons (light). The specific color (wavelength) of the light is determined by the energy bandgap of the semiconductor material used. The LTST-C193TGKT uses an Indium Gallium Nitride (InGaN) compound semiconductor, which is engineered to have a bandgap corresponding to green light (approximately 520-535 nm). The water-clear epoxy encapsulant protects the semiconductor die, acts as a lens, and may include phosphors (though not in this clear-lens case) to modify the output.

12. Development Trends

The trend in indicator and backlight LEDs for consumer electronics strongly aligns with the features of this component:

• Miniaturization and Lower Profile: Continuous demand for thinner devices drives the development of LEDs with ever-smaller footprints and heights, like this 0.4mm component.
• Higher Efficiency: Improvements in epitaxial growth and chip design yield more lumens per watt, allowing for brighter output at the same current or the same brightness with lower power consumption and less heat.
• Improved Color Consistency: Advanced binning techniques and tighter process controls enable manufacturers to offer LEDs with very narrow tolerances on wavelength and intensity, crucial for applications like full-color displays and ambient lighting.
• Enhanced Reliability for Harsh Environments: While this LED is for standard applications, the industry is also developing versions with higher temperature ratings and robustness for automotive and industrial uses.
• Integration: Trends include integrating multiple LED chips (RGB) into a single package or combining LEDs with driver ICs or sensors.

The LTST-C193TGKT represents a current-generation solution addressing the key needs of miniaturization and performance for mainstream electronics.