LTST-C193TBKT-2A Blue LED Datasheet - Dimensions 1.6x0.8x0.35mm - Voltage 2.55-2.95V - Power 76mW - English Technical Document

1. Product Overview

This document provides the complete technical specifications for the LTST-C193TBKT-2A, a surface-mount device (SMD) light-emitting diode (LED). This component belongs to a category of ultra-miniaturized optoelectronic devices designed for modern, space-constrained electronic assemblies. Its primary function is to provide a reliable, efficient blue light source for status indication, backlighting, and decorative lighting applications.

The core advantages of this LED are defined by its exceptionally low profile and high-brightness output. With a height of only 0.35 millimeters, it is classified as an extra-thin chip LED, enabling its use in ultra-slim consumer electronics, wearable devices, and other applications where vertical space is at a premium. The device utilizes an InGaN (Indium Gallium Nitride) semiconductor chip, which is the industry-standard technology for producing high-efficiency blue and green LEDs. This chip technology is known for its stability and performance.

The target market for this component is broad, encompassing manufacturers of office automation equipment, communication devices, household appliances, and various consumer electronics. Its compatibility with automatic pick-and-place equipment and standard infrared (IR) reflow soldering processes makes it suitable for high-volume, automated production lines, ensuring consistent quality and reducing assembly costs.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

The Absolute Maximum Ratings define the stress limits beyond which permanent damage to the device may occur. These are not operating conditions. For the LTST-C193TBKT-2A, the key limits are:

• Power Dissipation (Pd): 76 mW. This is the maximum amount of power the LED package can dissipate as heat without degrading its performance or lifespan. Exceeding this limit, typically by driving the LED with excessive current, will cause the junction temperature to rise uncontrollably.
• DC Forward Current (I_F): 20 mA. This is the maximum continuous forward current recommended for reliable long-term operation. The typical operating current for testing optical parameters is much lower at 2 mA.
• Peak Forward Current: 100 mA, but only under pulsed conditions with a 1/10 duty cycle and a 0.1 ms pulse width. This rating is important for applications requiring brief, high-intensity flashes.
• Temperature Ranges: The device can operate in ambient temperatures from -20°C to +80°C and can be stored in temperatures from -30°C to +100°C.
• Infrared Soldering Condition: The package can withstand a peak reflow temperature of 260°C for a maximum of 10 seconds, which is standard for lead-free (Pb-free) solder processes.

2.2 Electrical & Optical Characteristics

These parameters are measured at a standard ambient temperature of 25°C and define the device's performance under normal operating conditions.

• Luminous Intensity (I_V): Ranges from a minimum of 4.50 millicandelas (mcd) to a maximum of 18.0 mcd when driven at a forward current (I_F) of 2 mA. The intensity is measured using a sensor filtered to match the human eye's photopic response (CIE curve).
• Viewing Angle (2θ_1/2): 130 degrees. This wide viewing angle, characteristic of a water-clear lens without a diffuser, means the emitted light is spread over a broad area, making it suitable for applications requiring wide-area illumination rather than a focused beam.
• Peak Emission Wavelength (λ_P): 468 nanometers (nm). This is the specific wavelength at which the spectral power output is highest.
• Dominant Wavelength (λ_d): Ranges from 465.0 nm to 480.0 nm at I_F=2mA. This is the single wavelength perceived by the human eye that defines the color of the light, derived from the CIE chromaticity diagram.
• Spectral Line Half-Width (Δλ): 25 nm. This indicates the spectral purity; a smaller value would mean a more monochromatic light.
• Forward Voltage (V_F): Ranges from 2.55V to 2.95V at I_F=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 (I_R): Maximum of 10 microamperes (μA) when a reverse voltage (V_R) of 5V is applied. Important: This LED is not designed for reverse-bias operation; this test is for leakage characterization only.

3. Binning System Explanation

To ensure consistency in mass production, LEDs are sorted into performance bins. The LTST-C193TBKT-2A uses a three-dimensional binning system.

3.1 Forward Voltage Binning

Units are measured in Volts (V) at a test current of 2 mA. Bins ensure LEDs in a circuit will have similar voltage drops, promoting uniform brightness when connected in parallel.

• Bin A: 2.55V (Min) to 2.65V (Max)
• Bin 1: 2.65V to 2.75V
• Bin 2: 2.75V to 2.85V
• Bin 3: 2.85V to 2.95V

Tolerance within each bin is ±0.1V.

3.2 Luminous Intensity Binning

Units are in millicandelas (mcd) at I_F=2mA. This allows selection of LEDs for applications requiring specific brightness levels.

• Bin J: 4.50 mcd to 7.10 mcd
• Bin K: 7.10 mcd to 11.20 mcd
• Bin L: 11.20 mcd to 18.0 mcd

Tolerance within each bin is ±15%.

3.3 Dominant Wavelength Binning

Units are in nanometers (nm) at I_F=2mA. This controls the precise shade of blue.

• Bin AC: 465.0 nm to 470.0 nm (bluer, shorter wavelength)
• Bin AD: 470.0 nm to 475.0 nm
• Bin AE: 475.0 nm to 480.0 nm (slightly greener, longer wavelength)

Tolerance within each bin is ±1 nm.

4. Performance Curve Analysis

While specific graphs are referenced in the datasheet (e.g., Figure 1 for spectral distribution, Figure 6 for viewing angle), the typical behavior of such InGaN LEDs can be described:

• Current vs. Voltage (I-V) Curve: The forward voltage (V_F) has a positive temperature coefficient; it decreases slightly as the junction temperature increases for a given current. The curve is exponential near the turn-on voltage (~2.5V) and becomes more linear at higher currents.
• Luminous Intensity vs. Current (L-I Curve): The light output is approximately proportional to the forward current in the normal operating range (e.g., up to 20mA). However, efficiency (lumens per watt) typically peaks at a current lower than the maximum rating and then decreases due to thermal and droop effects.
• Temperature Characteristics: The luminous intensity of InGaN blue LEDs generally decreases as the junction temperature increases. The dominant wavelength also shifts slightly (usually to longer wavelengths) with increasing temperature.
• Spectral Distribution: The spectrum is a Gaussian-like curve centered around the peak wavelength of 468 nm, with a defined half-width of 25 nm.

5. Mechanical & Packaging Information

5.1 Package Dimensions

The LED conforms to an EIA standard package footprint. Key dimensions (in millimeters) include a length of 1.6mm, a width of 0.8mm, and the defining ultra-thin height of 0.35mm. Detailed mechanical drawings specify pad locations, component outline, and tolerances (typically ±0.10mm).

5.2 Polarity Identification

The cathode is typically marked, often by a notch, a green marking on the tape, or a beveled corner on the device itself. Correct polarity must be observed during assembly to prevent reverse bias damage.

5.3 Suggested Solder Pad Design

A land pattern recommendation is provided to ensure reliable solder joint formation and proper alignment during reflow. The suggested stencil thickness for solder paste application is a maximum of 0.10mm to prevent solder bridging between the closely spaced pads.

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Profile

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

• Pre-heat: 150°C to 200°C.
• Pre-heat Time: Maximum 120 seconds to properly activate the flux and minimize thermal shock.
• Peak Temperature: Maximum 260°C.
• Time Above Liquidus: The sample profile on page 3 shows the critical time the solder is molten, which must be controlled for proper joint formation.
• Total Soldering Time at Peak: Maximum 10 seconds. The process should not be repeated more than two times.

Because board design, paste, and oven characteristics vary, this profile is a generic target that must be validated for specific production setups.

6.2 Hand Soldering

If manual soldering is necessary, use a soldering iron with a temperature not exceeding 300°C, and limit the contact time to a maximum of 3 seconds for a single operation only. Excessive heat can damage the plastic package and the semiconductor die.

6.3 Cleaning

Do not use unspecified chemical cleaners. If cleaning is required after soldering, immerse the LED in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute. Aggressive solvents can damage the epoxy lens and package.

6.4 Storage & Handling

• ESD Precautions: LEDs are sensitive to electrostatic discharge (ESD). Use wrist straps, anti-static mats, and properly grounded equipment during handling.
• Moisture Sensitivity: While in its original sealed moisture-proof bag with desiccant, the device has a shelf life of one year when stored at ≤30°C and ≤90% RH. Once the bag is opened, the LEDs should be stored at ≤30°C and ≤60% RH.
• Floor Life: Components exposed to ambient air should undergo IR reflow within 672 hours (28 days). For longer exposure, store in a sealed container with desiccant or in a nitrogen desiccator. If exposed for more than 672 hours, a bake-out at approximately 60°C for at least 20 hours is recommended before soldering to remove absorbed moisture and prevent "popcorning" during reflow.

7. Packaging & Ordering Information

7.1 Tape and Reel Specifications

The LEDs are supplied in industry-standard embossed carrier tape, sealed with a top cover tape.

• Reel Size: 7 inches in diameter.
• Quantity per Reel: 5000 pieces.
• Minimum Packing Quantity: 500 pieces for remainder quantities.
• Missing Components: A maximum of two consecutive empty pockets in the tape is allowed.
• Standard: Packaging conforms to ANSI/EIA-481-1-A-1994 specifications.

8. Application Suggestions

8.1 Typical Application Scenarios

• Status Indicators: Power-on, battery charging, network activity, and mode indicators in smartphones, tablets, laptops, and IoT devices.
• Backlighting: For membrane switches, small LCD displays, or decorative panels in consumer electronics and appliances.
• Decorative Lighting: Accent lighting in automotive interiors, gaming peripherals, and home electronics.

8.2 Design Considerations

• Current Limiting: Always use a series resistor or a constant-current driver to limit the forward current to the desired level (e.g., 2mA for typical brightness or up to 20mA for maximum). Do not connect directly to a voltage source.
• Thermal Management: Although power dissipation is low, ensure adequate PCB copper area or thermal vias under the pads if operating at high ambient temperatures or near maximum current to help dissipate heat and maintain LED lifespan and color stability.
• Optical Design: The water-clear lens produces a Lambertian emission pattern (wide viewing angle). For a more focused beam, an external secondary optic (lens or light guide) would be required.
• Application Scope: This component is intended for standard commercial and industrial applications. For applications requiring exceptional reliability where failure could jeopardize safety (e.g., aviation, medical life-support), consultation with the component manufacturer for suitability assessment is mandatory.

9. Technical Comparison & Differentiation

The primary differentiating factor of the LTST-C193TBKT-2A is its 0.35mm height. Compared to standard 0603 or 0402 LEDs which are typically 0.6-0.8mm tall, this represents a 40-50% reduction in profile. This is a critical advantage in the ongoing trend of device miniaturization, particularly for smartphones, ultra-thin laptops, and wearable technology where internal space is severely limited.

Furthermore, its combination of this ultra-thin form factor with a relatively high luminous intensity (up to 18.0 mcd at only 2mA) is notable. Many similarly thin LEDs may sacrifice brightness. The use of a proven InGaN chip ensures good color consistency and reliability within its specified bins.

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 What resistor value should I use with a 5V supply?

Using Ohm's Law (R = (V_supply - V_F) / I_F) and assuming a typical V_F of 2.8V and a desired I_F of 10mA: R = (5V - 2.8V) / 0.010A = 220 Ohms. Always use the maximum V_F from the datasheet (2.95V) for a conservative design to ensure the current does not exceed the limit: R_min = (5V - 2.95V) / 0.010A = 205 Ohms (use 220Ω or 240Ω standard value).

10.2 Can I drive this LED at its maximum 20mA current continuously?

Yes, but with important considerations. At 20mA, the power dissipation is approximately 2.8V * 0.020A = 56mW, which is below the absolute maximum of 76mW. However, operating at the maximum rating will generate more heat, potentially reducing the LED's lifespan and causing a slight shift in color and a drop in luminous efficiency over time. For optimal longevity and stability, operating at a lower current (e.g., 5-10mA) is recommended if the brightness is sufficient.

10.3 Why is the viewing angle so wide (130°)?

The water-clear (non-diffused) epoxy lens is molded to create a hemispherical shape over the tiny LED chip. This shape acts as a lens that refracts light from the small point source, spreading it over a very wide angle. This is ideal for applications where the LED needs to be visible from many different viewing positions, not just head-on.

10.4 What is the difference between Peak Wavelength and Dominant Wavelength?

Peak Wavelength (λ_P): The physical wavelength at which the LED emits the most optical power. It is a property of the semiconductor material. Dominant Wavelength (λ_d): The perceptual wavelength. It is the single wavelength of monochromatic light that would appear to have the same color as the LED's light to a standard human observer. Due to the shape of the human eye's sensitivity curve and the LED's spectral width, these two values are different. Dominant wavelength is more relevant for color specification in design.

11. Practical Design and Usage Case

Scenario: Designing a multi-LED status bar for a portable Bluetooth speaker. The design requires 5 blue LEDs to indicate battery level. Space is extremely limited behind a thin plastic diffuser.

Component Selection: The LTST-C193TBKT-2A is chosen for its 0.35mm height, allowing it to fit in the slim enclosure. The wide 130° viewing angle ensures the light bar is visible from various angles.

Circuit Design: The LEDs are to be driven from a 3.3V regulator on the main board. Targeting a brightness level in the middle of Bin K (~9 mcd), a forward current of 5mA is selected for good visibility and power efficiency. Using the maximum V_F of 2.95V for a conservative design: R = (3.3V - 2.95V) / 0.005A = 70 Ohms. A standard 68Ω resistor is chosen, resulting in a slightly higher current of ~5.1mA.

PCB Layout: The recommended solder pad layout from the datasheet is used. A small amount of copper pour is connected to the cathode pads (which are typically thermally connected to the LED substrate) to aid in heat dissipation, especially since five LEDs will be grouped closely together.

Assembly: The LEDs are placed using automated equipment from the 8mm tape. The assembly line uses a lead-free reflow profile validated against the JEDEC-compliant suggestion in the datasheet, with careful monitoring of peak temperature and time above liquidus to prevent thermal damage to the ultra-thin package.

12. Technology Principle Introduction

The LTST-C193TBKT-2A is based on an InGaN (Indium Gallium Nitride) semiconductor chip. The principle of light emission is electroluminescence. When a forward voltage is applied across the p-n junction of the semiconductor, electrons from the n-type region and holes from the p-type region are injected into the active region. There, they recombine, releasing 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. By adjusting the ratio of Indium to Gallium in the InGaN compound, the bandgap can be tuned to produce light across the blue, green, and near-ultraviolet spectrum. The chip is then encapsulated in a clear epoxy resin that forms the lens, protects the delicate semiconductor structure from mechanical and environmental damage, and helps to extract the light efficiently from the chip.

13. Industry Trends and Developments

The development of LEDs like the LTST-C193TBKT-2A is driven by several key trends in the electronics industry:

• Miniaturization: The relentless push for thinner and smaller consumer devices demands components with ever-reduced footprints and heights. The 0.35mm profile represents a current benchmark for chip LEDs in high-volume applications.
• Increased Efficiency: Ongoing improvements in InGaN epitaxial growth and chip design continue to increase the luminous efficacy (lumens per watt) of blue LEDs, allowing for brighter output at lower currents, which reduces power consumption and heat generation.
• Advanced Packaging: Packaging technology is critical for ultra-thin devices. Developments in mold compounds, die-attach materials, and wafer-level packaging (WLP) techniques enable more robust and reliable miniature components.
• Automation and Standardization: The compatibility with tape-and-reel packaging, automatic placement, and standard reflow profiles is essential for integration into global, automated manufacturing ecosystems, keeping assembly costs low and quality high.

Future directions may include even thinner packages, integrated driver circuits within the LED package (smart LEDs), and further improvements in color consistency and thermal performance.