LTST-C190TBKT-10A Blue LED Datasheet - Size 3.2x1.6x0.8mm - Voltage 2.75-3.35V - Power 76mW - English Technical Document

1. Product Overview

This document details the specifications for a high-performance, surface-mount blue LED designed for modern electronic applications requiring compact form factors and reliable operation. The device is characterized by its exceptionally low profile, making it suitable for space-constrained designs such as ultra-thin displays, backlighting units, and portable consumer electronics.

The core advantages of this component include its compliance with RoHS and green product standards, ensuring environmental friendliness. It utilizes an InGaN (Indium Gallium Nitride) semiconductor chip, which is known for producing high-efficiency blue light. The package is fully compatible with standard automated pick-and-place assembly equipment and is qualified for use with lead-free (Pb-free) infrared reflow soldering processes, aligning with contemporary manufacturing requirements.

The target market encompasses a broad range of industries, including but not limited to consumer electronics (smartphones, tablets, laptops), automotive interior lighting, status indicators, panel lighting, and general decorative illumination where a bright, reliable blue point source is needed.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

The device's operational limits are defined under an ambient temperature (Ta) of 25°C. The maximum continuous power dissipation is 76 milliwatts (mW). The DC forward current should not exceed 20 mA for reliable long-term operation. For pulsed applications, a peak forward current of 100 mA is permissible under specific conditions: a 1/10 duty cycle and a pulse width of 0.1 milliseconds. The component is rated for an operating temperature range of -20°C to +80°C and can be stored in environments ranging from -30°C to +100°C. Crucially, it can withstand infrared reflow soldering at a peak temperature of 260°C for a duration of 10 seconds, which is standard for Pb-free assembly.

2.2 Electrical & Optical Characteristics

Key performance parameters are measured at Ta=25°C and a standard test current (IF) of 10 mA.

• Luminous Intensity (Iv): Ranges from a minimum of 18.0 millicandelas (mcd) to a typical value of 90.0 mcd. This is measured using a sensor and filter combination that approximates the standard CIE photopic eye-response curve.
• Viewing Angle (2θ1/2): A wide viewing angle of 130 degrees is specified. This is defined as the off-axis angle where the luminous intensity drops to half of its axial (on-axis) value.
• Peak Wavelength (λP): The wavelength at which the spectral emission is strongest is typically 468 nanometers (nm).
• Dominant Wavelength (λd): This parameter, derived from the CIE chromaticity diagram, defines the perceived color of the LED. It ranges from 465.0 nm to 475.0 nm.
• Spectral Bandwidth (Δλ): The spectral line half-width is 25 nm, indicating the spread of wavelengths emitted around the peak.
• Forward Voltage (VF): At 10 mA, the voltage drop across the LED ranges from 2.75 Volts (min) to 3.35 Volts (max).
• Reverse Current (IR): With a reverse voltage (VR) of 5V applied, the leakage current is a maximum of 10 microamperes (μA). It is critical to note that the device is not designed for operation under reverse bias; this test condition is for characterization only.

Electrostatic Discharge (ESD) Caution: The LED is sensitive to static electricity and voltage surges. Proper ESD handling procedures, including the use of grounded wrist straps, anti-static gloves, and grounded equipment, are mandatory during handling and assembly to prevent damage.

3. Binning System Explanation

To ensure consistency in production and application, LEDs are sorted into performance bins based on key parameters. This allows designers to select components that meet specific circuit and optical requirements.

3.1 Forward Voltage Binning

Units are categorized into bins (J8, J9, J10, J11) based on their forward voltage at 10 mA. Each bin has a tolerance of ±0.1V.

• J8: 2.75V - 2.90V
• J9: 2.90V - 3.05V
• J10: 3.05V - 3.20V
• J11: 3.20V - 3.35V

3.2 Luminous Intensity Binning

LEDs are binned (M1, M2, N1, N2, P1, P2, Q1) according to their luminous intensity output at 10 mA, with a tolerance of ±15% per bin. This range spans from 18.0 mcd (M1 min) to 90.0 mcd (Q1 max).

3.3 Dominant Wavelength Binning

The color consistency is controlled through wavelength bins AC and AD, each with a tolerance of ±1 nm.

• AC: 465.0 nm - 470.0 nm
• AD: 470.0 nm - 475.0 nm

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (e.g., Figure 1 for spectral emission, Figure 6 for viewing angle), the provided data allows for critical analysis. The relationship between forward current (IF) and luminous intensity (Iv) is typically super-linear at lower currents, becoming more linear and then saturating at higher currents. Designers must operate within the specified DC current limit to avoid accelerated degradation. The forward voltage has a negative temperature coefficient, meaning it decreases slightly as the junction temperature increases. The spectral characteristics (peak and dominant wavelength) are also temperature-dependent, generally shifting to longer wavelengths (red-shift) with increased temperature, which is a fundamental property of semiconductor light sources.

5. Mechanical & Packaging Information

5.1 Package Dimensions

The device features an EIA-standard package with ultra-thin geometry. The key dimension is its height of 0.80 mm (maximum). Other critical dimensions include the length and width, which are standard for this package type, ensuring compatibility with automated assembly. All dimensional tolerances are typically ±0.10 mm unless otherwise specified. Detailed dimensioned drawings are essential for PCB land pattern design.

5.2 Polarity Identification & Pad Design

The component has anode and cathode terminals. Polarity is typically indicated by a marking on the package, such as a notch, dot, or cut corner. The datasheet includes suggested soldering pad dimensions to ensure a reliable solder joint, proper alignment, and sufficient thermal relief during the reflow process. Adhering to these recommendations is crucial for manufacturing yield and long-term reliability.

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Profile

A suggested infrared (IR) reflow profile is provided for Pb-free assembly processes. This profile is based on JEDEC standards to ensure reliable mounting. Key parameters include:

• Pre-heat: 150°C to 200°C.
• Pre-heat Time: Maximum of 120 seconds to allow for uniform heating and solvent evaporation.
• Peak Temperature: Maximum of 260°C.
• Time Above Liquidus: The component should be exposed to the peak temperature for a maximum of 10 seconds. Reflow should be performed a maximum of two times.

It is emphasized that the optimal profile depends on the specific PCB design, solder paste, and oven characteristics, and board-level characterization is recommended.

6.2 Hand Soldering

If hand soldering is necessary, extreme care must be taken. The soldering iron tip temperature should not exceed 300°C, and the contact time with the LED terminal should be limited to a maximum of 3 seconds for a single operation only. Excessive heat can irreversibly damage the LED chip or the plastic package.

6.3 Cleaning

Unspecified chemical cleaners should not be used as they may damage the LED package. If cleaning is required after soldering (e.g., to remove flux residue), the recommended method is to immerse the assembled board in ethyl alcohol or isopropyl alcohol at normal room temperature for less than one minute.

7. Storage & Handling

Proper storage is vital to maintain solderability and prevent moisture-induced damage ("popcorning") during reflow.

• Sealed Package: LEDs in their original moisture-proof barrier bag with desiccant should be stored at ≤30°C and ≤90% Relative Humidity (RH). The shelf life under these conditions is one year.
• Opened Package: Once the barrier bag is opened, the components are exposed to ambient humidity. They should be stored at ≤30°C and ≤60% RH. It is strongly recommended to complete the IR reflow process within one week of opening.
• Extended Storage (Opened): For storage beyond one week, components should be placed in a sealed container with desiccant or in a nitrogen-purged desiccator.
• Baking: Components stored out of their original packaging for more than one week must be baked at approximately 60°C for at least 20 hours prior to soldering to drive out absorbed moisture.

8. Packaging & Ordering Information

The product is supplied in a tape-and-reel format compatible with automated assembly machines.

• Tape Width: 8 mm.
• Reel Diameter: 7 inches.
• Quantity per Reel: 4000 pieces.
• Minimum Order Quantity (MOQ): 500 pieces for remainder quantities.
• Packing Standard: Complies with ANSI/EIA-481-1-A-1994 specifications. Empty pockets in the carrier tape are sealed with cover tape.

The part number LTST-C190TBKT-10A encodes specific attributes: likely series (LTST-C190), color (Blue/B), package variant (KT), and bin code (10A).

9. Application Notes & Design Considerations

9.1 Typical Application Scenarios

This LED is designed for use in ordinary electronic equipment, including:

• Status and indicator lights on consumer devices (routers, chargers, appliances).
• Backlighting for keys, symbols, or small LCD panels.
• Decorative lighting in automotive interiors.
• General purpose illumination where a compact blue light source is required.

Important Notice: The device is not intended for applications where failure could directly jeopardize life or health (e.g., aviation control, medical life-support, critical safety systems). Consultation with the manufacturer is required for such high-reliability applications.

9.2 Circuit Design Considerations

1. Current Limiting: An LED is a current-driven device. A series current-limiting resistor is mandatory when driving from a voltage source to set the operating current and prevent thermal runaway. The resistor value is calculated using Ohm's Law: R = (V_supply - V_F) / I_F. Use the maximum V_F from the datasheet for a conservative design.
2. Power Dissipation: Ensure the product of I_F and V_F does not exceed the absolute maximum power rating of 76 mW, considering the worst-case operating temperature.
3. Reverse Voltage Protection: As the LED has a low reverse breakdown voltage, circuit designs should prevent the application of reverse bias. In AC or bidirectional signal applications, a parallel protection diode may be necessary.
4. Thermal Management: Although the power is low, ensuring adequate PCB copper area around the solder pads helps dissipate heat, maintaining LED performance and longevity, especially in high ambient temperature environments.
5. ESD Protection: Incorporate ESD protection devices (e.g., TVS diodes) on input lines if the LED is in an exposed location, such as a panel indicator.

10. Technical Comparison & Differentiation

The primary differentiating factor of this component is its ultra-low profile of 0.80 mm. Compared to standard SMD LEDs which are often 1.0 mm or taller, this allows for integration into increasingly thinner end products. The use of an InGaN chip provides higher efficiency and brighter output compared to older technologies for blue emission. Its qualification for standard Pb-free IR reflow makes it a drop-in replacement for many existing designs seeking to reduce component height without changing the assembly process. The comprehensive binning system offers designers flexibility to select cost-optimized or performance-optimized grades for their specific application.

11. Frequently Asked Questions (FAQs)

Q1: What is the difference between Peak Wavelength and Dominant Wavelength?
A1: Peak Wavelength (λP) is the physical wavelength where the spectral power output is highest. Dominant Wavelength (λd) is a calculated value from colorimetry that represents the single wavelength of a pure monochromatic light that would match the perceived color of the LED. λd is more relevant for color-based applications.

Q2: Can I drive this LED at 20 mA continuously?
A2: Yes, 20 mA is the maximum rated DC forward current. However, for maximum longevity and to account for real-world thermal conditions, driving it at a lower current (e.g., 10-15 mA) is often a good practice, as luminous efficiency is often still high at these levels.

Q3: Why is baking required before soldering?
A3: Plastic SMD packages can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can vaporize rapidly, creating internal pressure that can crack the package or delaminate internal interfaces—a phenomenon known as "popcorning." Baking removes this moisture.

Q4: How do I interpret the bin code "10A" in the part number?
A4: The "10A" suffix typically specifies a combination of performance bins for forward voltage, luminous intensity, and dominant wavelength. One must cross-reference the bin code list in the datasheet or with the manufacturer to know the exact guaranteed ranges for V_F, I_v, and λ_d for that specific order code.

12. Practical Design Example

Scenario: Designing a blue power status indicator for a USB-powered device (5V supply).
Step 1 - Choose Operating Point: Select a mid-range current of 12 mA for a good balance of brightness and lifetime.
Step 2 - Determine Forward Voltage: Use the maximum V_F from the J11 bin for a conservative design: 3.35V.
Step 3 - Calculate Series Resistor: R = (5.0V - 3.35V) / 0.012A = 137.5 Ω. The nearest standard E24 value is 150 Ω.
Step 4 - Re-calculate Actual Current: Using a typical V_F of 3.0V (from J10 bin), I_F = (5.0V - 3.0V) / 150Ω ≈ 13.3 mA, which is safe and within limits.
Step 5 - Verify Power: Worst-case power in LED: P = 3.35V * 13.3mA ≈ 44.6 mW, which is well below the 76 mW maximum.
Step 6 - PCB Layout: Place the 150Ω resistor in series with the LED's anode. Provide a small copper pour connected to the LED's cathode pad for slight heat sinking. Ensure polarity marking on the PCB silkscreen matches the LED's marking.

13. Technology Introduction

This LED is based on InGaN (Indium Gallium Nitride) semiconductor technology grown on a substrate, typically sapphire or silicon carbide. When a forward voltage is applied, electrons and holes recombine in the active quantum well region of the semiconductor, releasing energy in the form of photons (light). The specific composition of the InGaN alloy determines the bandgap energy and thus the wavelength (color) of the emitted light—in this case, blue. The water-clear lens epoxy is formulated to be transparent to this wavelength and provides environmental protection and mechanical stability. The ultra-thin profile is achieved through advanced package molding and die-attach techniques.

14. Industry Trends

The trend in SMD LEDs for consumer electronics continues toward miniaturization and higher efficiency. The 0.8mm height of this device represents a step in this direction, enabling thinner end products. There is also a continuous drive for higher luminous efficacy (more light output per electrical watt input) from InGaN chips. Furthermore, tighter binning tolerances and more sophisticated color mixing capabilities are in demand for applications requiring precise and uniform color reproduction, such as full-color RGB displays and advanced automotive lighting. The integration of driver circuitry and multiple LED chips into single packages (e.g., COB - Chip-on-Board) is another significant trend, though discrete LEDs like this one remain essential for point-source indicators and flexible design layouts.