SMD LED LTST-C190TGKT-5A Datasheet - Size 1.6x0.8x0.6mm - Voltage 3.2V - Green - English Technical Document

1. Product Overview

This document details the specifications for a high-performance, surface-mount chip LED. The device is characterized by its exceptionally thin profile, making it suitable for applications with stringent height restrictions. It is a green light-emitting diode utilizing InGaN (Indium Gallium Nitride) semiconductor technology, encapsulated in a water-clear lens package. The product is designed for compatibility with modern automated assembly processes, including infrared reflow soldering, and adheres to environmental standards as a RoHS-compliant green product.

The core advantages of this LED include its ultra-compact form factor, high luminous intensity output, and robust construction suitable for high-volume manufacturing. Its primary target markets are consumer electronics, indicator lights, backlighting for small displays, and any application requiring a reliable, bright, and miniaturized green light source.

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 forward current (DC) is rated at 20 mA. For pulsed operation, a peak forward current of 100 mA is permissible under a strict 1/10 duty cycle with a pulse width of 0.1 ms. The total power dissipation must not exceed 76 mW. The component can operate within a temperature range of -20°C to +80°C and can be stored in environments ranging from -30°C to +100°C. Crucially, it is rated for infrared reflow soldering at a peak temperature of 260°C for a maximum of 10 seconds.

2.2 Electrical & Optical Characteristics

Key performance metrics are measured at Ta=25°C and a standard test current (IF) of 5 mA. The luminous intensity (Iv) has a typical value of 60.0 millicandelas (mcd), with a minimum specified value of 28.0 mcd. This indicates a bright output suitable for daylight-visible indicators. The device features a very wide viewing angle (2θ1/2) of 130 degrees, providing a broad, uniform light distribution.

Electrically, the forward voltage (VF) typically measures 3.20 volts, with a range defined by the binning system. The reverse current (IR) is specified at a maximum of 10 μA when a reverse voltage (VR) of 5V is applied, though the device is not designed for reverse-bias operation. Optically, the dominant wavelength (λd) is typically 525 nm, placing it in the green spectrum, with a spectral half-width (Δλ) of 35 nm. The peak emission wavelength (λp) is approximately 530 nm.

3. Binning System Explanation

To ensure consistency in mass production, LEDs are sorted into performance bins. This allows designers to select components that meet specific tolerance requirements for their application.

3.1 Forward Voltage Binning

Units are categorized by their forward voltage at 5mA. Bin codes D6, D7, and D8 represent voltage ranges of 2.60-2.80V, 2.80-3.00V, and 3.00-3.20V respectively, each with a tolerance of ±0.1V.

3.2 Luminous Intensity Binning

LEDs are binned based on their light output at 5mA. Codes N, P, Q, and R correspond to intensity ranges of 28.0-45.0 mcd, 45.0-71.0 mcd, 71.0-112.0 mcd, and 112.0-180.0 mcd, respectively. A tolerance of ±15% applies to each bin.

3.3 Dominant Wavelength Binning

The color (wavelength) is binned to control hue variation. Bin codes AP, AQ, and AR cover the green spectrum ranges of 520.0-525.0 nm, 525.0-530.0 nm, and 530.0-535.0 nm, with a tight tolerance of ±1 nm per bin.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (e.g., Figure 1 for spectral distribution, Figure 5 for viewing angle), the provided data allows for analytical understanding. The relationship between forward current and luminous intensity is generally linear within the operating range. The forward voltage exhibits a negative temperature coefficient, meaning it decreases slightly as the junction temperature increases. The spectral distribution curve would show a single peak centered around 530 nm with the stated 35 nm half-width, confirming a pure green color emission.

5. Mechanical & Package Information

The LED is an EIA-standard package with ultra-thin dimensions. The key characteristic is its height of only 0.80 mm. Detailed dimensional drawings specify the length, width, lead spacing, and overall geometry to ensure proper PCB footprint design. The package uses a water-clear lens material. Polarity is indicated by the physical structure of the component, typically with a cathode mark. Recommended solder pad dimensions are provided to ensure reliable solder joint formation and proper alignment during reflow.

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Profile

A suggested infrared reflow profile is provided for lead-free (Pb-free) solder processes. This profile is based on JEDEC standards. Key parameters include a pre-heat stage between 120-150°C, a maximum peak temperature of 260°C, and a time above liquidus (typically 217°C for Pb-free solder) not exceeding 10 seconds. The profile aims to minimize thermal stress on the LED package while ensuring proper solder reflow.

6.2 Handling & Storage

The device is sensitive to Electrostatic Discharge (ESD). Handling with grounded wrist straps or anti-static gloves is recommended. In its original sealed moisture-proof bag with desiccant, the shelf life is one year when stored at ≤30°C and ≤90% RH. Once the bag is opened, components should be stored at ≤30°C and ≤60% RH and used within one week. For storage beyond one week outside the original packaging, baking at approximately 60°C for at least 20 hours is required before soldering to remove absorbed moisture and prevent \"popcorning\" during reflow.

6.3 Cleaning

If cleaning after soldering is necessary, 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. Unspecified chemicals may damage the package epoxy or lens.

7. Packaging & Ordering Information

The components are supplied in tape-and-reel packaging compatible with automated pick-and-place equipment. The tape width is 8 mm, wound on 7-inch diameter reels. Each full reel contains 4000 pieces. A minimum order quantity of 500 pieces applies for partial reels. The packaging conforms to ANSI/EIA 481-1-A-1994 specifications. The part number LTST-C190TGKT-5A follows the manufacturer's internal coding system, where elements likely denote the series, color (TG for green), and specific bin codes for intensity and wavelength.

8. Application Recommendations

8.1 Typical Application Scenarios

This LED is ideal for status indicators in portable devices (phones, tablets, wearables), backlighting for small LCDs or keypads, panel indicators in industrial controls, and decorative lighting in consumer products. Its thin profile is critical for modern slim designs.

8.2 Design Considerations

Circuit designers must include a current-limiting resistor in series with the LED. The resistor value is calculated using Ohm's Law: R = (Vsupply - VF) / IF, where VF is the forward voltage from the chosen bin and IF is the desired drive current (not to exceed 20 mA DC). For uniform brightness in multi-LED arrays, selecting LEDs from the same intensity bin (e.g., all from bin P) is advised. Thermal management on the PCB should ensure the operating temperature around the LED does not exceed 80°C to maintain longevity and stable light output.

9. Technical Comparison & Differentiation

The primary differentiator of this LED is its 0.8mm height, which is thinner than many standard chip LEDs (e.g., 0603 or 0805 packages which are often >1.0mm tall). Compared to older technology like AlGaInP LEDs, the InGaN chip provides higher efficiency and brightness, particularly in the green/blue spectrum. The wide 130-degree viewing angle offers more omnidirectional light compared to LEDs with narrower viewing angles, which is beneficial for applications where the viewing position is not fixed directly on-axis.

10. Frequently Asked Questions (FAQs)

Q: Can I drive this LED at 20mA continuously?
A: Yes, 20mA is the maximum rated DC forward current. For optimal longevity, driving at a lower current such as 10-15mA is common and will still provide ample brightness while reducing stress and heat.

Q: What is the difference between dominant wavelength and peak wavelength?
A: Dominant wavelength (λd) is derived from the CIE color chart and represents the perceived color. Peak wavelength (λp) is the actual physical peak of the emitted spectrum. They are often close but not identical.

Q: Why is baking necessary if the reel has been opened for more than a week?
A: The plastic package can absorb moisture from the air. During the high-temperature reflow process, this moisture can vaporize rapidly, causing internal delamination or cracking (\"popcorning\"). Baking drives out this absorbed moisture.

Q: Can I use a soldering iron instead of reflow?
A: Manual soldering with an iron is possible but not recommended for volume production. If necessary, the iron tip temperature must not exceed 300°C, and contact time must be limited to 3 seconds maximum for a single soldering event.

11. Practical Application Case Study

Consider a design for a smartwatch with multiple notification LEDs. The height restriction inside the watch case is severe, at 1.0mm. A standard LED might be 1.2mm tall, causing fit issues. This 0.8mm tall LED fits perfectly. The designer selects bins D7 for voltage (2.8-3.0V) and P for intensity (45-71 mcd) to ensure consistent brightness and power consumption from the watch's 3.3V supply. The wide 130-degree viewing angle ensures the notification light is visible even when the watch face is glanced at from an angle. The LEDs are placed on the PCB, and the assembly undergoes a standard lead-free reflow process using the provided profile, resulting in reliable solder joints without damaging the components.

12. Technology Principle Introduction

This LED is based on InGaN (Indium Gallium Nitride) semiconductor material. When a forward voltage is applied across the p-n junction, electrons and holes are injected into the active region. They recombine, releasing energy in the form of photons (light). The specific composition of the InGaN alloy determines the bandgap energy, which in turn dictates the wavelength (color) of the emitted light. For green emission, the indium content is carefully controlled. The water-clear epoxy lens encapsulates and protects the semiconductor chip, and its shape is designed to optimize the light extraction and viewing angle.

13. Industry Trends & Developments

The trend in SMD LEDs continues toward miniaturization, higher efficiency (more light output per watt of electrical input), and improved color consistency. The drive for thinner devices, as seen in this product, is driven by the relentless pursuit of slimmer consumer electronics. Furthermore, there is increasing integration, with LEDs being combined with drivers and control ICs into single packages. The underlying InGaN technology is also central to the development of high-power LEDs for general lighting and micro-LEDs for next-generation displays, indicating a robust and evolving technological foundation.