LTST-C190TBKT-5A Blue LED Datasheet - Dimensions 3.2x1.6x0.8mm - Voltage 2.65-3.05V - Power 76mW - English Technical Document

1. Product Overview

The LTST-C190TBKT-5A is a surface-mount device (SMD) light-emitting diode (LED) designed for modern, compact electronic applications. Its core advantage lies in its exceptionally low profile, with a height of just 0.8 millimeters, making it suitable for applications where space constraints are critical, such as in ultra-thin displays, backlighting for mobile devices, and indicator lights in slim consumer electronics. The device utilizes an InGaN (Indium Gallium Nitride) semiconductor chip, which is known for producing high-brightness blue light efficiently. It is packaged in industry-standard 8mm tape on 7-inch reels, ensuring compatibility with high-speed automated pick-and-place assembly equipment commonly used in mass production.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. The maximum continuous forward current (I_F) is 20 mA. Under pulsed operation with a 1/10 duty cycle and a 0.1ms pulse width, a peak forward current of 100 mA is permissible. The maximum power dissipation is 76 mW, calculated from the forward voltage and current. The device is rated for an operating temperature range of -20°C to +80°C and can be stored in temperatures from -30°C to +100°C. A critical parameter for assembly is the infrared reflow soldering condition, which must not exceed 260°C for 10 seconds to prevent thermal damage to the LED package and die.

2.2 Electro-Optical Characteristics

Measured at a standard test current of 5 mA and an ambient temperature of 25°C, the key performance parameters are defined. The luminous intensity (I_V) has a typical value, with a minimum of 11.2 mcd and a maximum of 45.0 mcd as per the binning system. The dominant wavelength (λ_d), which defines the perceived color, is specified between 470.0 nm and 475.0 nm, placing it in the blue spectrum. The peak emission wavelength (λ_Peak) is typically around 468 nm. The spectral half-width (Δλ) is approximately 25 nm, indicating the spectral purity of the emitted blue light. The forward voltage (V_F) ranges from 2.65 V to 3.05 V at 5 mA. The reverse current (I_R) is limited to a maximum of 10 μA when a reverse voltage of 5V is applied, though the device is not designed for reverse-bias operation.

3. Binning System Explanation

To ensure consistency in mass production, LEDs are sorted into performance bins. The LTST-C190TBKT-5A uses a three-dimensional binning system.

3.1 Forward Voltage Binning

Forward voltage is binned into four codes (1, 2, 3, 4) with a tolerance of ±0.1V per bin. For example, Bin Code 1 covers V_F from 2.65V to 2.75V at 5mA. This allows designers to select LEDs with tighter voltage matching for applications where current regulation is critical.

3.2 Luminous Intensity Binning

Luminous intensity is binned into six codes (L1, L2, M1, M2, N1, N2) with a tolerance of ±15% per bin. The range spans from a minimum of 11.2 mcd (L1) to a maximum of 45.0 mcd (N2). This enables selection based on required brightness levels for different applications.

3.3 Dominant Wavelength Binning

The dominant wavelength is binned into a single code (AD) ranging from 470.0 nm to 475.0 nm, with a tight tolerance of ±1 nm. This ensures very consistent blue color output across all devices.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet, their implications are critical. The relationship between forward current (I_F) and forward voltage (V_F) is non-linear and temperature-dependent. The luminous intensity is directly proportional to the forward current but will decrease as the junction temperature rises. Understanding these curves is essential for designing appropriate drive circuits, especially for maintaining stable brightness over the operating temperature range and for implementing pulse-width modulation (PWM) dimming effectively.

5. Mechanical and Packaging Information

5.1 Package Dimensions

The LED has an EIA-standard package footprint. Key dimensions include a length of 3.2 mm, a width of 1.6 mm, and the defining ultra-thin height of 0.8 mm. Polarity is clearly indicated by the cathode mark on the package. Detailed dimensioned drawings are provided for PCB land pattern design.

5.2 Tape and Reel Specifications

The components are supplied in 8mm wide embossed carrier tape on 7-inch (178 mm) diameter reels. Each reel contains 4000 pieces. The packaging conforms to ANSI/EIA 481-1-A-1994 standards, ensuring reliability during automated handling. Notes specify that a minimum of 500 pieces can be ordered as remnants and that a maximum of two consecutive component pockets may be empty (sealed with cover tape).

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A suggested infrared (IR) reflow profile is provided for lead-free (Pb-free) solder processes. The profile must adhere to JEDEC standards. Key parameters include a pre-heat zone up to 150-200°C, a peak body temperature not exceeding 260°C, and a time above 260°C limited to a maximum of 10 seconds. The total pre-heat time should be limited to 120 seconds maximum. It is strongly recommended to characterize the profile for specific PCB designs, solder pastes, and oven types.

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 3 seconds maximum. This should be performed only once to avoid thermal stress.

6.3 Cleaning

If cleaning after soldering is required, only specified solvents should be used. Immersing the LED in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute is acceptable. The use of unspecified chemical cleaners can damage the LED package material.

7. Storage and Handling Precautions

7.1 Electrostatic Discharge (ESD) Protection

This LED is sensitive to electrostatic discharge. It is mandatory to handle the device in an ESD-protected area using wrist straps or anti-static gloves. All equipment and machinery must be properly grounded to prevent surge damage.

7.2 Moisture Sensitivity

The LEDs are packaged in a moisture-barrier bag with desiccant. While sealed, they should be stored at 30°C or less and 90% relative humidity (RH) or less, with a recommended shelf life of one year. Once the original bag is opened, the storage environment should not exceed 30°C and 60% RH. Components exposed to ambient air for more than one week should be baked at approximately 60°C for at least 20 hours before reflow soldering to remove absorbed moisture and prevent \"popcorning\" damage during assembly.

8. Application Suggestions and Design Considerations

8.1 Typical Application Scenarios

This LED is ideal for status indicators, backlighting for keypads and LCDs, decorative lighting, and panel illumination in consumer electronics, office equipment, and communication devices. Its thin profile makes it perfect for applications where vertical space is limited.

8.2 Circuit Design Notes

A current-limiting resistor is always required when driving the LED from a voltage source. The resistor value (R) can be calculated using Ohm's Law: R = (V_source - V_F) / I_F. For stable operation and longevity, driving the LED at or below the recommended 20 mA continuous current is advised. For brightness control, PWM dimming is preferred over analog dimming (reducing current), as it maintains a consistent color temperature. Designers must ensure the PCB land pattern matches the recommended layout to achieve reliable solder joints and proper alignment.

8.3 Thermal Management

Although the power dissipation is low (76 mW max), effective thermal management via the PCB copper pads is important. Excessive junction temperature will reduce light output (luminous intensity) and accelerate the degradation of the LED. Ensuring adequate copper area around the solder pads helps dissipate heat.

9. Technical Comparison and Differentiation

The primary differentiating factor of this LED is its 0.8 mm height, which is thinner than many standard SMD LEDs (e.g., 0603 or 0805 packages which are often >1.0 mm tall). This allows for design innovations in ultra-slim products. The use of InGaN technology provides higher brightness and efficiency compared to older technologies for blue LEDs. The comprehensive binning system offers designers the ability to select components with precise optical and electrical characteristics for high-consistency applications.

10. Frequently Asked Questions (FAQ)

10.1 What is the difference between dominant wavelength and peak wavelength?

Peak wavelength (λ_Peak) is the single wavelength at which the emission spectrum is strongest. Dominant wavelength (λ_d) is derived from the CIE chromaticity diagram and represents the single wavelength that best matches the perceived color of the light as seen by the human eye. For a monochromatic source like this blue LED, they are typically very close, but λ_d is the more relevant parameter for color specification.

10.2 Can I drive this LED without a current-limiting resistor?

No. An LED is a current-driven device. Connecting it directly to a voltage source exceeding its forward voltage will cause excessive current to flow, potentially destroying it instantly due to thermal runaway. A series resistor or a constant-current driver circuit is always necessary.

10.3 Why is the storage condition after opening the bag so strict?

SMD LED 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 layers—a phenomenon known as \"popcorning.\" The specified storage conditions and baking procedure prevent this failure mode.

11. Practical Design and Usage Case

Consider designing a slim Bluetooth speaker with a thin status indicator bar. The 0.8mm height of the LTST-C190TBKT-5A allows it to be mounted directly behind a 1mm thick diffuser panel, creating a seamless, low-profile illuminated effect. By selecting LEDs from the same intensity bin (e.g., M2) and voltage bin, you ensure uniform brightness and current draw across multiple LEDs driven in parallel from a single regulated voltage line with individual series resistors. The blue color provides a modern, high-tech aesthetic. The compatibility with IR reflow allows it to be soldered simultaneously with all other SMD components on the main PCB, streamlining assembly.

12. Technology Principle Introduction

This LED is based on InGaN semiconductor material. When a forward voltage is applied across the p-n junction, electrons and holes are injected into the active region. When these charge carriers recombine, they release energy in the form of photons (light). The specific bandgap energy of the InGaN alloy determines the wavelength (color) of the emitted light, which in this case is in the blue spectrum (~470-475 nm). The \"water clear\" lens material is typically a transparent epoxy or silicone that does not alter the color but helps in directing the light output.

13. Industry Trends and Developments

The trend in SMD LEDs for consumer electronics continues toward miniaturization, higher efficiency (more light output per watt), and improved color consistency. The 0.8mm height of this device represents a step in the miniaturization trend. Furthermore, there is a growing emphasis on tighter binning tolerances and advanced packaging to improve thermal performance, allowing for higher drive currents and brightness from ever-smaller packages. The move toward lead-free and RoHS-compliant manufacturing processes, as seen in this device's specified reflow profile, is now a universal industry standard.