LTST-C19MGEBK-RR SMD LED Datasheet - Full Color RGB - 0.5mm Height - 20-30mA Forward Current - English Technical Document

1. Product Overview

This document details the specifications for the LTST-C19MGEBK-RR, a surface-mount device (SMD) LED lamp. This component is part of a family of miniature LEDs designed specifically for automated printed circuit board (PCB) assembly processes and applications where space is a critical constraint. The device integrates three distinct LED chips within a single, compact package, enabling the emission of red, green, and blue light. This full-color capability makes it suitable for a diverse range of modern electronic equipment.

1.1 Core Advantages and Target Market

The primary advantages of this LED include its exceptionally thin profile, high brightness output, and compliance with environmental and manufacturing standards. Its design prioritizes compatibility with high-volume, automated production environments.

• Target Applications: The LED is well-suited for telecommunications devices (cordless and cellular phones), portable computing (notebook computers), network system equipment, various home appliances, and indoor signage or display applications.
• Key Features: The device is compliant with the Restriction of Hazardous Substances (RoHS) directive. It features an extra-thin package height of 0.5mm. It utilizes high-performance Ultra Bright InGaN (for green and blue) and AlInGaP (for red) semiconductor chips. It is supplied packaged in 8mm tape on 7-inch diameter reels, adhering to EIA standard packaging for automated handling.
• Manufacturing Compatibility: The component is designed to be compatible with integrated circuits (I.C. compatible) and standard automatic placement equipment. It can withstand infrared (IR) reflow soldering processes, which is the standard for surface-mount technology assembly.

2. Technical Parameters: In-Depth Objective Interpretation

The performance of the LED is defined under specific environmental and electrical test conditions, primarily at an ambient temperature (Ta) of 25°C. Understanding these parameters is crucial for reliable circuit design.

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed and should be avoided in design.

• Power Dissipation (Pd): 76 mW for Green and Blue chips; 75 mW for the Red chip. This is the maximum power the LED can dissipate as heat.
• Peak Forward Current (I_FP): 100 mA for Green/Blue, 80 mA for Red, under a 1/10 duty cycle with 0.1ms pulse width. This rating is for pulsed operation, not continuous DC.
• DC Forward Current (I_F): The maximum continuous current: 20 mA for Green and Blue chips; 30 mA for the Red chip.
• Temperature Ranges: Operating: -20°C to +80°C; Storage: -30°C to +85°C.
• Soldering Condition: Withstands infrared reflow soldering at a peak temperature of 260°C for 10 seconds, which is typical for lead-free (Pb-free) solder processes.

2.2 Electro-Optical Characteristics

These are the typical performance values measured under specified test conditions. Designers should use these as guidelines, noting the minimum and maximum limits.

• Luminous Intensity (I_V): Measured in millicandelas (mcd). The minimum value is 180 mcd, tested at different forward currents for each color: Green at 2mA, Red at 4.8mA, Blue at 3mA. The maximum is 450 mcd. The intensity is measured using a sensor and filter approximating the CIE standard eye-response curve.
• Viewing Angle (2θ_1/2): The typical full viewing angle is 120 degrees, indicating a wide-angle emission pattern.
• Wavelength Parameters:
  • Peak Emission Wavelength (λ_P): Typical values are 518 nm (Green), 632 nm (Red), and 468 nm (Blue). This is the wavelength at which the spectral output is strongest.
  • Dominant Wavelength (λ_d): Typical values are 525 nm (Green), 624 nm (Red), and 470 nm (Blue). This is the single wavelength perceived by the human eye that defines the color.
  • Spectral Line Half-Width (Δλ): Typical values are 35 nm (Green), 20 nm (Red), and 25 nm (Blue). This indicates the spectral purity or bandwidth of the emitted light.
• Forward Voltage (V_F): The voltage drop across the LED when operating at its test current. Ranges are: Green: 2.20V min, 3.00V max; Red: 1.70V min, 2.40V max; Blue: 2.20V min, 3.00V max.
• Reverse Current (I_R): Maximum leakage current of 50 μA (Green/Blue) and 10 μA (Red) when a reverse voltage (V_R) of 5V is applied. The device is not designed for reverse operation; this parameter is for test purposes only.

3. Binning System Explanation

To ensure color and brightness consistency in production, LEDs are sorted into bins based on measured performance. The LTST-C19MGEBK-RR uses two primary binning criteria.

3.1 Luminous Intensity (I_V) Rank

LEDs are classified based on their measured luminous intensity at the standard test currents. The bin codes and their ranges are:

• S1: 180 mcd (Min) to 225 mcd (Max)
• S2: 225 mcd to 285 mcd
• T1: 285 mcd to 355 mcd
• T2: 355 mcd to 450 mcd

A tolerance of +/-15% is applied to each luminous intensity bin.

3.2 Hue (Color) Rank

This is a more complex binning system based on the CIE 1931 chromaticity coordinates (x, y), which scientifically define color points. The datasheet provides a detailed grid of bin codes (A, B, C, D and their sub-variants A1, B1, etc.) with specific coordinate boundaries that form quadrilaterals on the chromaticity diagram. This allows for precise selection of LEDs with nearly identical color output. A tolerance of +/-0.01 is applied to each hue bin's (x, y) coordinates. The dominant wavelength (λ_d) is derived from these coordinates.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (e.g., Fig.1, Fig.5), their typical characteristics can be described based on the technology and parameters provided.

4.1 Forward Current vs. Forward Voltage (I-V Curve)

The I-V relationship for LEDs is non-linear and exponential. The forward voltage (V_F) values provided in the specifications are snapshots at specific test currents. In practice, V_F will increase with increasing I_F and is also temperature-dependent. The different V_F ranges for Red (~1.7-2.4V) versus Green/Blue (~2.2-3.0V) necessitate careful design of current-limiting circuits, especially in multi-color applications.

4.2 Luminous Intensity vs. Forward Current

The light output (I_V) is generally proportional to the forward current (I_F) within the operating range. However, efficiency may drop at very high currents due to increased heat. The datasheet specifies different test currents for each color to achieve comparable brightness levels, reflecting the different efficiencies of the InGaN and AlInGaP chip technologies.

4.3 Temperature Characteristics

LED performance is sensitive to temperature. The luminous intensity typically decreases as the junction temperature increases. The specified operating temperature range of -20°C to +80°C defines the ambient conditions under which the device will meet its published specifications. Proper thermal management on the PCB is essential to maintain performance and longevity, especially given the device's thin profile which may have limited thermal mass.

5. Mechanical and Package Information

5.1 Package Dimensions and Pin Assignment

The LED comes in a standard SMD package. The lens is water clear. The internal source colors and their corresponding pin assignments are: InGaN Green on pins 1 and 4; AlInGaP Red on pins 2 and 5; InGaN Blue on pins 3 and 6. All dimensions are in millimeters with a typical tolerance of ±0.1 mm unless otherwise noted. The ultra-thin height of 0.5mm is a key mechanical feature.

5.2 Recommended PCB Attachment Pad

The datasheet includes a diagram showing the recommended copper pad layout on the PCB for soldering the LED. Adhering to this footprint is critical for achieving reliable solder joints, proper alignment, and effective heat dissipation during the reflow process and operation.

6. Soldering and Assembly Guidelines

6.1 IR Reflow Soldering Condition

For lead-free (Pb-free) solder processes, a suggested reflow profile is provided, with a peak temperature of 260°C sustained for 10 seconds. This is a standard profile for many SMD components and ensures the LED package is not damaged by excessive heat.

6.2 Cleaning

If cleaning after soldering is necessary, only specified chemicals should be used. The datasheet recommends immersing the LED in ethyl alcohol or isopropyl alcohol at normal temperature for less than one minute. Unspecified chemicals could damage the package material.

6.3 Electrostatic Discharge (ESD) Caution

The LED chips are sensitive to static electricity and voltage surges. It is strongly recommended to use proper ESD controls when handling these devices: wrist straps, anti-static gloves, and ensuring all equipment and machinery are properly grounded.

6.4 Storage Conditions

Sealed Package: LEDs should be stored at 30°C or less and 90% relative humidity (RH) or less. When packed in a moisture-proof bag with desiccant, they should be used within one year.
Opened Package: The storage ambient should not exceed 30°C or 60% RH. Components removed from their original packaging should undergo IR reflow soldering within one week (Moisture Sensitivity Level 3, MSL 3). For longer storage outside the original bag, they should be kept in a sealed container with desiccant or in a nitrogen ambient.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The LEDs are supplied in industry-standard embossed carrier tape, 8mm in width, wound onto 7-inch (178mm) diameter reels. Each full reel contains 4000 pieces. The tape has a cover tape to seal the component pockets. The packaging conforms to ANSI/EIA-481 specifications. For remnant quantities, the minimum packing quantity is 500 pieces.

8. Application Suggestions and Design Considerations

8.1 Typical Application Scenarios

• Keyboard/Keypad Backlighting: Its thin profile and RGB capability make it ideal for illuminating keys on portable devices, potentially with color-changing effects.
• Status Indicators: Can provide multi-color status information (e.g., red for error, green for ready, blue for active) in a single component footprint.
• Micro-Displays and Symbol Luminaires: Suitable for small, color informational displays or backlighting symbols on control panels.

8.2 Design Considerations

• Current Driving: Use constant current drivers or appropriate current-limiting resistors for each color channel independently, due to their different V_F and I_F characteristics.
• Thermal Management: Ensure the PCB design allows for heat dissipation from the LED pad, especially if driving at or near maximum current.
• Optical Design: The 120-degree viewing angle provides wide emission. Consider diffusers or light guides if a more uniform or directed output is required.
• Binning for Consistency: For applications requiring uniform color and brightness across multiple units, specify the required I_V and Hue bin codes during procurement.

9. Technical Comparison and Differentiation

The LTST-C19MGEBK-RR differentiates itself primarily through its ultra-thin 0.5mm height, which is advantageous for increasingly slim consumer electronics. The integration of three high-performance chips (InGaN for G/B, AlInGaP for R) in one package offers superior brightness and color gamut compared to older phosphor-converted white LEDs or less efficient chip technologies. Its full compliance with automated assembly processes (tape-and-reel, IR reflow) makes it a cost-effective choice for high-volume manufacturing, distinguishing it from LEDs requiring manual soldering.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive all three colors (RGB) from a single constant current source?
A: No. The forward voltage (V_F) ranges differ significantly between the red chip and the green/blue chips. They must be driven by separate current-regulated circuits or have individually calculated current-limiting resistors.

Q: What is the difference between Peak Wavelength and Dominant Wavelength?
A: Peak Wavelength (λ_P) is the physical peak of the light spectrum the LED emits. Dominant Wavelength (λ_d) is the perceptual single wavelength the human eye associates with the color. λ_d is more relevant for color specification in displays and lighting.

Q: The MSL is rated 3. What does this mean for my production process?
A: Moisture Sensitivity Level 3 means the package can be exposed to factory floor conditions (≤30°C/60% RH) for up to 168 hours (7 days) before it must be soldered. If exceeded, the parts may need to be baked to remove absorbed moisture before reflow to prevent "popcorning" damage.

11. Practical Design and Usage Case

Scenario: Designing a multi-color status indicator for a portable IoT device.
The design requires a single, tiny component to show network status (blue: connecting, green: connected, red: error) and battery status (green: high, red: low). The LTST-C19MGEBK-RR is selected for its thinness and RGB capability. The designer:
1. Lays out the PCB using the recommended pad footprint.
2. Designs three separate low-side MOSFET switch circuits, each with a series resistor calculated for the specific V_F range of the target color (Red, Green, Blue) to achieve the desired current (e.g., 15mA for good brightness at low power).
3. Ensures the microcontroller GPIO pins can sink the required current.
4. Specifies a tight Hue bin (e.g., B1 for green) during ordering to ensure the "connected" green color is consistent across all production units.
5. Plans the assembly process to ensure the reel is used within the MSL 3 timeframe after opening.

12. Principle Introduction

Light emission in LEDs is based on electroluminescence in semiconductor materials. When a forward voltage is applied across the p-n junction of the chip, electrons and holes recombine, releasing energy in the form of photons (light). The specific wavelength (color) of the light is determined by the bandgap energy of the semiconductor material. This device uses:
- Indium Gallium Nitride (InGaN): A compound semiconductor whose bandgap can be tuned by adjusting the indium content. It is used here to produce green and blue light.
- Aluminium Indium Gallium Phosphide (AlInGaP): Another compound semiconductor, excellent for producing high-efficiency red and amber light. The water-clear lens allows the intrinsic chip color to be seen directly without color conversion.

13. Development Trends

The evolution of SMD LEDs like this one follows several clear industry trends: Miniaturization (thinner, smaller footprints) to enable sleeker end products. Increased Efficiency (higher luminous intensity per mA) to reduce power consumption in battery-operated devices. Enhanced Color Rendering and Gamut through advanced chip materials like InGaN and AlInGaP for more vivid and accurate displays. Improved Reliability and Standardization for seamless integration into fully automated, high-speed assembly lines, as evidenced by the detailed binning, tape-and-reel specs, and reflow profiles provided in this datasheet.