SMD LED LTST-S33FBEGW-5A Datasheet - Dimensions 3.3x3.3x0.4mm - Voltage 1.7-3.1V - Power 50-76mW - Full Color RGB - English Technical Documentation

1. Product Overview

This document provides the complete technical specifications for the LTST-S33FBEGW-5A, a surface-mount device (SMD) LED lamp. This component integrates three distinct semiconductor chips within a single, ultra-thin package to produce full-color (RGB) light output. Designed for automated printed circuit board (PCB) assembly processes, it is ideal for applications where space conservation, high reliability, and vibrant color indication are critical requirements.

1.1 Core Features and Target Market

The primary advantages of this LED include its compliance with environmental regulations, compact form factor, and high-brightness output. The device is constructed using advanced semiconductor materials: InGaN (Indium Gallium Nitride) for the blue and green emitters, and AlInGaP (Aluminum Indium Gallium Phosphide) for the red emitter. This material selection is responsible for its superior luminous efficiency. The package is supplied on industry-standard 8mm tape reels, facilitating high-speed pick-and-place manufacturing. Its design is fully compatible with infrared (IR) reflow soldering processes, making it suitable for modern electronics production lines. Target applications span telecommunications equipment, office automation devices, home appliances, industrial control panels, and consumer electronics, where it is commonly used for keyboard backlighting, status indicators, and symbolic illumination.

2. Technical Parameters: In-Depth Objective Interpretation

The performance of the LTST-S33FBEGW-5A is defined by a comprehensive set of electrical, optical, and thermal parameters measured under standard conditions (Ta=25°C). Understanding these parameters is essential for proper circuit design and reliable operation.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed.

• Power Dissipation (Pd): Varies by color channel: 76 mW for Blue and Green, 50 mW for Red. This parameter indicates the maximum allowable power loss as heat.
• Peak Forward Current (I_FP): The maximum pulsed current (100 mA for B/G, 80 mA for R at 1/10 duty cycle, 0.1ms pulse width) the LED can withstand momentarily.
• DC Forward Current (I_F): The recommended maximum continuous forward current for all three colors is 20 mA.
• Electrostatic Discharge (ESD) Threshold: The device is sensitive to ESD. The Human Body Model (HBM) rating is 150V for Blue/Green and 2000V for Red, necessitating proper ESD handling procedures.
• Temperature Ranges: Operating: -20°C to +80°C. Storage: -30°C to +100°C.
• IR Reflow Soldering: Withstands a peak temperature of 260°C for a maximum of 10 seconds.

2.2 Electrical and Optical Characteristics

These are the typical performance parameters measured at a standard test current of 5 mA.

• Luminous Intensity (I_V): The light output measured in millicandelas (mcd). Minimum values are 35 mcd (Blue), 45 mcd (Red), and 45 mcd (Green), with maximums reaching 180 mcd and 280 mcd respectively.
• Viewing Angle (2θ_1/2): A wide viewing angle of 130 degrees (typical), providing a broad emission pattern suitable for indicator applications.
• Wavelength Parameters:
  • Peak Wavelength (λ_P): 468 nm (Blue), 632 nm (Red), 518 nm (Green).
  • Dominant Wavelength (λ_d): Defines the perceived color. Ranges: 465-475 nm (B), 620-630 nm (R), 525-540 nm (G).
  • Spectral Line Half-Width (Δλ): Indicates color purity. Typical values: 25 nm (B), 17 nm (R), 35 nm (G).
• Forward Voltage (V_F): The voltage drop across the LED at 5 mA. Ranges: 2.6-3.1V (B), 1.7-2.3V (R), 2.6-3.1V (G). This is critical for driver circuit design.
• Reverse Current (I_R): Maximum leakage current of 10 µA at a reverse bias of 5V. The device is not designed for reverse operation.

3. Binning System Explanation

To ensure color and brightness consistency in production, LEDs are sorted into performance bins. The LTST-S33FBEGW-5A uses a binning system primarily for luminous intensity.

3.1 Luminous Intensity Binning

Each color channel has its own set of bin codes defining minimum and maximum intensity ranges at 5 mA. The tolerance within each bin is +/-15%.

• Blue: Bins N2 (35-45 mcd), P (45-71), Q (71-112), R (112-180).
• Red & Green: Bins P (45-71 mcd), Q (71-112), R (112-180), S (180-280).

This system allows designers to select components with guaranteed minimum brightness levels for their application. The bin code is marked on the product packaging.

4. Performance Curve Analysis

Graphical data provides deeper insight into device behavior under varying conditions. While specific curves are referenced in the datasheet, typical analyses include:

4.1 Current vs. Voltage (I-V) Characteristic

This curve shows the relationship between forward current (I_F) and forward voltage (V_F). It is non-linear, typical of a diode. The curve for the Red LED (AlInGaP) will typically have a lower knee voltage (~1.8V) compared to the Blue and Green LEDs (InGaN, ~2.8V). This difference must be accounted for in multi-color driver designs, often requiring separate current-limiting resistors or channels.

4.2 Luminous Intensity vs. Forward Current

This graph illustrates how light output increases with current. The relationship is generally linear within the recommended operating range but will saturate at higher currents. It is crucial to operate within the DC forward current limit (20mA) to maintain efficiency and prevent accelerated degradation.

4.3 Spectral Distribution

The spectral output graph shows the relative radiant power as a function of wavelength for each chip. It confirms the peak and dominant wavelengths and visually represents the spectral half-width, which correlates with color saturation. Narrower peaks (like Red's 17 nm) indicate higher color purity.

5. Mechanical and Package Information

5.1 Package Dimensions and Pin Assignment

The device conforms to an EIA standard package outline. Key dimensions include a body size of approximately 3.3mm x 3.3mm with an ultra-thin profile of 0.4mm. Pin assignment is as follows: Pin 1: Green cathode, Pin 3: Red anode, Pin 4: Blue anode. A detailed dimensioned drawing is essential for PCB footprint design, ensuring proper solder joint formation and mechanical alignment.

5.2 Recommended PCB Pad Layout and Polarity

The datasheet provides a suggested land pattern (solder pad design) for the PCB. Adhering to this pattern is critical for achieving reliable solder joints during reflow, preventing tombstoning, and ensuring proper thermal and electrical connection. The polarity marking on the device (typically a dot or beveled corner near Pin 1) must be correctly aligned with the PCB silkscreen marking.

6. Soldering and Assembly Guidelines

6.1 IR Reflow Soldering Profile

For lead-free (Pb-free) solder processes, a specific thermal profile is recommended:

• Pre-heat: 150-200°C for a maximum of 120 seconds to gradually heat the assembly and activate flux.
• Peak Temperature: Maximum of 260°C.
• Time Above Liquidus: The device should be subjected to the peak temperature for a maximum of 10 seconds. The reflow process should not be repeated more than twice.

Profiles must be characterized for the specific PCB design, component mix, and oven used.

6.2 Hand Soldering

If manual soldering is necessary, use a temperature-controlled iron set to a maximum of 300°C. Contact time with any lead should be limited to 3 seconds, and this should be performed only once to prevent thermal damage to the plastic package and wire bonds.

6.3 Cleaning and Storage

Post-solder cleaning should use alcohol-based solvents like isopropyl alcohol (IPA). Do not use unspecified chemicals. For storage, unopened moisture-barrier bags (MSL 3) should be kept below 30°C and 90% RH. Once opened, components should be used within one week or stored in a dry nitrogen or desiccated environment. If stored exposed for over a week, a bake-out at 60°C for 20+ hours is required before soldering to remove absorbed moisture and prevent "popcorning" during reflow.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The product is supplied for automated assembly on 8mm wide embossed carrier tape wound onto 7-inch (178mm) diameter reels. Standard reel quantity is 4000 pieces. The tape pockets are sealed with a protective cover tape. Packaging follows ANSI/EIA-481 standards, with allowances for a maximum of two consecutive missing components and a minimum pack quantity of 500 pieces for partial reels.

8. Application Suggestions and Design Considerations

8.1 Typical Application Circuits

Each color channel must be driven independently with a series current-limiting resistor. The resistor value (R_series) is calculated using Ohm's Law: R_series = (V_supply - V_F) / I_F. Due to the different V_F of the Red channel, its resistor value will differ from the Blue and Green channels even for the same desired current. For precise color mixing or dimming, constant current drivers or PWM (Pulse Width Modulation) control are recommended.

8.2 Thermal Management

Although power dissipation is low, proper thermal design extends LED life. Ensure the PCB pad design provides adequate copper area to act as a heat sink. Avoid operating at absolute maximum current and temperature ratings for prolonged periods.

8.3 ESD Protection

Implement ESD protection measures on PCBs handling these LEDs, especially if they are user-accessible. Use transient voltage suppression (TVS) diodes or other protection circuits on signal lines. During handling, use grounded workstations and wrist straps.

9. Technical Comparison and Differentiation

The key differentiators of this component are its integration of three high-performance chips (InGaN for B/G, AlInGaP for R) in a single 0.4mm thin package. Compared to older technologies using less efficient materials for red light, the AlInGaP chip offers superior brightness and efficiency. The unified package simplifies assembly versus using three discrete LEDs, saving board space and placement time. The wide 130-degree viewing angle is suitable for applications requiring broad visibility.

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 Can I drive all three colors with a single resistor?

No. The forward voltage (V_F) of the red chip (1.7-2.3V) is significantly lower than that of the blue and green chips (2.6-3.1V). Using a common resistor would result in severely mismatched currents, potentially overdriving the red LED or underdriving the blue/green LEDs. Each color channel requires its own current-limiting element.

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

Peak Wavelength (λ_P) is the wavelength at which the spectral power output is maximum. Dominant Wavelength (λ_d) is the single wavelength of monochromatic light that matches the perceived color of the LED. λ_d is more relevant for color specification in applications.

10.3 How do I interpret the luminous intensity bin code?

The bin code (e.g., 'R' for Blue) guarantees that the LED's intensity at 5 mA falls within a specified range (e.g., 112-180 mcd). Selecting a higher bin code (like 'R' or 'S') ensures a brighter minimum output. For consistent appearance in a product, specify and use components from the same bin.

11. Practical Design and Usage Case

Scenario: Designing a multi-status indicator for a consumer router. The device needs to show power (steady white), network activity (flashing blue), and error (red). Using the LTST-S33FBEGW-5A simplifies the design: one component handles all colors. The microcontroller's GPIO pins, each with a series resistor calculated for 5-10 mA per channel, drive the LED. White is created by turning on Red, Green, and Blue simultaneously at appropriate currents (may require calibration for pure white). The wide viewing angle ensures visibility from various angles. The thin profile fits within the router's slim enclosure. The tape-and-reel packaging allows for fast, automated assembly during mass production.

12. Operating Principle Introduction

Light emission in LEDs is based on electroluminescence in a semiconductor p-n junction. When a forward voltage is applied, electrons and holes are injected into the active region where they recombine. The energy released during this recombination is emitted as a photon (light). The specific wavelength (color) of the photon is determined by the bandgap energy of the semiconductor material. InGaN materials have a wider bandgap, producing higher-energy photons in the blue/green spectrum. AlInGaP has a different bandgap structure optimized for producing high-efficiency red and amber light. The "white diffused" lens material scatters the light from the three individual chips to create a blended output and a wider viewing angle.

13. Technology Trends

The field of SMD LEDs continues to evolve towards higher efficiency (more lumens per watt), increased power density, and improved color rendering. There is a trend for further miniaturization while maintaining or increasing light output. Advances in phosphor technology for white LEDs and new semiconductor materials like GaN-on-Si (Gallium Nitride on Silicon) aim to reduce costs. For multi-color chips, integration with built-in drivers (IC-driven LEDs) and smarter, addressable packages (like WS2812-type LEDs) are becoming more common, simplifying system design for dynamic lighting applications. The emphasis on reliability and performance under high-temperature operation also remains a key development focus.