SMD LED LTST-E683FGBW Datasheet - Orange/Green/Blue - 20mA - 80mW - English Technical Document

1. Product Overview

This document details the specifications for a surface-mount device (SMD) LED component identified as LTST-E683FGBW. This is a multi-color LED component integrating three distinct light-emitting chips within a single package: an orange AlInGaP chip, a green InGaN chip, and a blue InGaN chip. The device is designed for automated assembly processes and is compatible with infrared reflow soldering, making it suitable for high-volume electronics manufacturing. The diffused lens provides a wide viewing angle, enhancing visibility from various perspectives.

2. Technical Parameter Deep Dive

2.1 Absolute Maximum Ratings

The device's operational limits are defined at an ambient temperature (Ta) of 25°C. Exceeding these ratings may cause permanent damage.

• Power Dissipation (Pd): Orange: 72 mW; Green/Blue: 80 mW. This parameter indicates the maximum power the LED can safely dissipate as heat under continuous DC operation.
• Peak Forward Current (IFP): Orange: 80 mA; Green/Blue: 100 mA. This is the maximum allowable pulsed current, specified under a 1/10 duty cycle with a 0.1ms pulse width, useful for brief, high-intensity flashes.
• DC Forward Current (IF): Orange: 30 mA; Green/Blue: 20 mA. This is the recommended maximum continuous forward current for reliable long-term operation.
• Temperature Ranges: Operating: -40°C to +85°C; Storage: -40°C to +100°C. These ranges define the environmental conditions the device can withstand during use and when inactive.

2.2 Electrical & Optical Characteristics

Key performance metrics are measured at Ta=25°C and a standard test current (IF) of 20mA, unless otherwise noted.

• Luminous Intensity (Iv): Measured in millicandelas (mcd), it represents the perceived brightness of the light source. The orange and blue LEDs have a typical range of 140-355 mcd, while the green LED is brighter, ranging from 355-900 mcd. Measurement follows the CIE photopic eye-response curve.
• Viewing Angle (2θ1/2): Typically 120 degrees. This is the full angle at which the luminous intensity drops to half of its peak axial value, indicating a very wide emission pattern.
• Wavelength Parameters:
  • Peak Wavelength (λP): The wavelength at which the spectral power distribution is maximum. Typical values: Orange: 611 nm, Green: 518 nm, Blue: 468 nm.
  • Dominant Wavelength (λd): The single wavelength that perceptually matches the LED's color. Typical values: Orange: 605 nm, Green: 525 nm, Blue: 470 nm. This is derived from the CIE chromaticity diagram.
  • Spectral Half-Width (Δλ): The bandwidth of the emitted spectrum at half its maximum intensity. Typical values: Orange: 17 nm (narrow), Green: 35 nm, Blue: 25 nm.
• Forward Voltage (VF): The voltage drop across the LED when conducting the specified current. Ranges: Orange: 1.8-2.4V; Green/Blue: 2.8-3.8V. Tolerance is +/- 0.1V. This is critical for driver circuit design.
• Reverse Current (IR): Maximum 10 μA at a reverse voltage (VR) of 5V. The device is not designed for reverse-bias operation; this parameter is for leakage current characterization only.

3. Binning System Explanation

The LEDs are sorted into bins based on their measured luminous intensity at 20mA to ensure color and brightness consistency within a production batch.

• Orange & Blue Bins: Use codes R2, S1, S2, T1, with intensity ranges from 140.0 mcd (R2 Min) to 355.0 mcd (T1 Max).
• Green Bins: Use codes T2, U1, U2, V1, with higher intensity ranges from 355.0 mcd (T2 Min) to 900.0 mcd (V1 Max).
• Tolerance: Each intensity bin has a +/-11% tolerance on the nominal values, accounting for minor variations.

Designers should specify the required bin codes when ordering to guarantee the desired brightness levels for their application, especially in multi-LED arrays where uniformity is important.

4. Performance Curve Analysis

The datasheet references typical characteristic curves (not fully detailed in the provided excerpt). These curves, typically plotted, would include:

• I-V (Current-Voltage) Curve: Shows the relationship between forward current and forward voltage for each color chip. It demonstrates the exponential turn-on characteristic of a diode and helps in selecting current-limiting resistors or designing constant-current drivers.
• Luminous Intensity vs. Forward Current: Illustrates how light output increases with current, usually in a near-linear relationship within the recommended operating range before efficiency drops at very high currents.
• Luminous Intensity vs. Ambient Temperature: Shows the derating of light output as the junction temperature rises, which is crucial for thermal management in high-power or high-ambient-temperature applications.
• Spectral Distribution: Graphs the relative radiant power versus wavelength for each LED, visually representing the peak wavelength, dominant wavelength, and spectral half-width.

5. Mechanical & Packaging Information

5.1 Package Dimensions

The device conforms to an EIA standard SMD package outline. All dimensions are in millimeters with a general tolerance of ±0.2 mm unless otherwise specified. The specific dimensional drawing would show the length, width, height, lead spacing, and lens geometry.

5.2 Pin Assignment

The tri-color LED has a common-cathode or common-anode configuration (implied by single package). The pinout is: Pin 1: Orange Anode, Pin 3: Blue Anode, Pin 4: Green Anode (with a common cathode, likely on pins 2 and/or 5, as per standard 4-pin RGB LED footprints). This must be verified against the detailed package drawing for correct PCB layout.

5.3 Tape and Reel Packaging

The components are supplied in industry-standard embossed carrier tape on 7-inch (178 mm) diameter reels to facilitate automated pick-and-place assembly.

• Tape Dimensions: The tape width, pocket pitch, and pocket dimensions are specified to be compatible with standard feeder equipment.
• Reel Specifications: Standard 7-inch reel containing 2000 pieces. Minimum order quantity for remainder reels is 500 pieces.
• Cover Tape: Empty pockets are sealed with a top cover tape.
• Quality: Conforms to ANSI/EIA-481 specifications. The maximum allowable number of consecutive missing components in the tape is two.

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Profile

The device is compatible with infrared (IR) reflow soldering processes. A lead-free soldering profile compliant with J-STD-020B is recommended.

• Pre-heat: 150-200°C for a maximum of 120 seconds to gradually heat the board and activate flux.
• Peak Temperature: Should not exceed 260°C. The time above liquidus (e.g., 217°C) should be controlled as per the solder paste manufacturer's recommendation.
• Soldering Time: The total time at peak temperature should be limited to a maximum of 10 seconds. Reflow should be performed a maximum of two times.

Note: The optimal profile depends on the specific PCB design, solder paste, and oven. The JEDEC-based profile serves as a generic target.

6.2 Hand Soldering

If hand soldering is necessary, extreme care must be taken:

• Iron Temperature: Maximum 300°C.
• Soldering Time: Maximum 3 seconds per joint.
• Limit: Hand soldering should be performed only once to avoid thermal stress damage to the LED package or wire bonds.

6.3 Cleaning

Unspecified chemical cleaners should be avoided as they may damage the LED epoxy lens or package. If cleaning is required post-soldering:

• Use alcohol-based solvents such as ethyl alcohol or isopropyl alcohol.
• Immerse the LED at normal room temperature.
• Limit immersion time to less than one minute.

6.4 Storage & Handling

• Sealed Package: Store at ≤30°C and ≤70% Relative Humidity (RH). Shelf life is one year when stored in the original moisture-proof bag with desiccant.
• Opened Package: Components exposed to ambient air should be stored at ≤30°C and ≤60% RH. It is strongly recommended to complete the IR reflow process within 168 hours (7 days) of opening the bag to prevent moisture absorption, which can cause "popcorning" during reflow.
• Extended Storage (Opened): For storage beyond 168 hours, place components in a sealed container with desiccant or in a nitrogen-purged desiccator.
• Baking: Components stored out of their original packaging for more than 168 hours must be baked at approximately 60°C for at least 48 hours prior to soldering to remove absorbed moisture.

7. Application Suggestions

7.1 Typical Application Scenarios

This tri-color SMD LED is designed for general-purpose indicator and backlighting applications in consumer and industrial electronics where multiple status colors are needed from a single compact component. Examples include:

• Multi-status indicators on network equipment, routers, or servers (e.g., power/activity/error).
• Backlighting for buttons or icons on control panels, remote controls, or appliances.
• Decorative lighting or status displays in automotive interiors (non-critical functions).
• Portable electronic device status indicators.

Important Application Restriction: The datasheet explicitly states these LEDs are for "ordinary electronic equipment." They are not qualified for safety-critical applications where failure could jeopardize life or health, such as in aviation, medical life-support, or transportation safety systems. For such applications, components with appropriate reliability qualifications must be sourced.

7.2 Design Considerations

• Current Limiting: Always use external current-limiting resistors or a constant-current driver for each color channel. Calculate resistor values based on the supply voltage, the LED's forward voltage (VF, use Max. value for safety), and the desired forward current (IF, do not exceed DC rating).
• Thermal Management: While power dissipation is low, ensure adequate PCB copper area or thermal vias if operating at high ambient temperatures or maximum current to maintain junction temperature within limits and ensure long-term reliability and stable light output.
• PCB Pad Design: Follow the recommended pad layout from the datasheet's package drawing to ensure proper solder joint formation and mechanical stability during reflow.
• ESD Protection: Although not explicitly stated, standard ESD handling precautions for semiconductor devices are recommended during assembly.

8. Technical Comparison & Differentiation

While a direct comparison with other part numbers is not provided in this single datasheet, key differentiating features of this component can be inferred:

• Tri-Color in One Package: Integrates three discrete colors, saving PCB space and assembly cost compared to using three separate single-color LEDs.
• Wide Viewing Angle (120°): The diffused lens provides omnidirectional visibility, superior to narrow-angle LEDs used for focused beams.
• High Brightness Green: The green chip offers significantly higher luminous intensity (up to 900 mcd) compared to the orange and blue, which may be designed to balance perceived brightness across colors due to human eye sensitivity.
• Robust Packaging: Compatibility with IR reflow and automatic placement indicates a package designed for modern, reliable SMT assembly processes.
• Standardized Binning: The defined binning structure allows for predictable and consistent optical performance in production runs.

9. Frequently Asked Questions (Based on Technical Parameters)

Q1: Can I drive all three colors at their maximum DC current (30mA Orange, 20mA Green/Blue) simultaneously?
A: No. The Absolute Maximum Rating for total Power Dissipation (Pd) must not be exceeded. Simultaneous operation at max currents would result in a total power dissipation exceeding the 80mW limit for the package (calculated as VF*IF for each chip and summed). You must derate the operating currents or use pulsed operation to stay within the total Pd limit.

Q2: What is the difference between Peak Wavelength and Dominant Wavelength?
A: Peak Wavelength (λP) is the physical peak of the light spectrum the LED emits. Dominant Wavelength (λd) is a calculated value that represents the perceived color hue as a single wavelength on the CIE chart. For monochromatic LEDs, they are often close; for broader spectra (like green), they can differ more. λd is more relevant for color matching.

Q3: Why is the reverse current rating important if the LED is not for reverse operation?
A: The IR rating (10 μA max at 5V) is a leakage specification. It ensures that if a small reverse voltage is accidentally applied (e.g., during circuit transients or in multiplexed designs), the device will not draw excessive current. It is a reliability parameter, not an operating condition.

Q4: How critical is the 168-hour floor life after opening the bag?
A: Very critical for reflow soldering. Moisture absorbed into the plastic package can vaporize rapidly during the high-temperature reflow cycle, causing internal delamination, cracks, or "popcorning," which leads to failure. Adhering to the 168-hour window or following the baking procedure is essential for yield and reliability.

10. Practical Design Case

Scenario: Designing a status indicator for a device powered by a 5V rail. The indicator must show Orange for "Standby," Green for "Normal Operation," and Blue for "Error." Only one color is on at a time.

Design Steps:

1. Select Operating Current: Choose a safe, standard value like 15mA for all colors, well below the DC maximums, ensuring longevity and reducing thermal load.
2. Calculate Current-Limiting Resistors:
   • Use the maximum VF from the datasheet for safety margin: Orange: 2.4V, Green: 3.8V, Blue: 3.8V.
   • Supply Voltage (Vs) = 5V. Formula: R = (Vs - VF) / IF.
     • R_Orange = (5V - 2.4V) / 0.015A ≈ 173 Ω (use 180 Ω standard value).
     • R_Green = (5V - 3.8V) / 0.015A ≈ 80 Ω (use 82 Ω standard value).
     • R_Blue = (5V - 3.8V) / 0.015A ≈ 80 Ω (use 82 Ω standard value).
   • Recalculate actual current with standard resistors: I_Orange = (5-2.4)/180 ≈ 14.4mA (safe).
3. Check Power Dissipation:
   • Worst-case single LED power: P = VF * IF. Using typical VF for estimate: P_Green ≈ 3.3V * 0.0144A ≈ 47.5 mW, which is below the 80 mW limit for the Green/Blue chip. The Orange chip dissipates even less. Since only one is on at a time, total package Pd is not exceeded.
4. PCB Layout: Place the LED and its three resistors close together. Use the recommended pad layout from the mechanical drawing. Ensure the correct pin assignment (1=Orange, 3=Blue, 4=Green) is mapped to the driver circuit (e.g., microcontroller GPIO pins with series resistors).
5. Driver Circuit: Use microcontroller pins configured as open-drain or with series resistors to sink current to ground (if common cathode) or source current (if common anode).

11. Operating Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light through electroluminescence. When a forward voltage is applied across the p-n junction, electrons from the n-type material recombine with holes from the p-type material in the active region. This recombination releases energy in the form of photons (light). The specific wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor materials used in the active region.

• Orange LED: Uses an Aluminium Indium Gallium Phosphide (AlInGaP) semiconductor, which has a bandgap corresponding to red/orange/amber light.
• Green & Blue LEDs: Use Indium Gallium Nitride (InGaN) semiconductors. By varying the indium/gallium ratio, the bandgap can be tuned to emit across the blue, green, and cyan spectrum. Achieving efficient green emission with InGaN is more challenging than blue, which is reflected in the different performance characteristics (e.g., forward voltage, efficiency).

The three chips are mounted inside a reflective cavity within a plastic package. A diffused epoxy lens encapsulates the chips, providing environmental protection, shaping the light output beam (120° viewing angle), and mixing the light from the individual chips if multiple are lit simultaneously to create other colors (like white, if a phosphor were present, which it is not in this RGB device).

12. Technology Trends

The technology represented by this component sits within broader trends in optoelectronics:

• Increased Efficiency: Ongoing materials science and chip design improvements continue to raise the luminous efficacy (lumens per watt) of LEDs, allowing brighter output at lower currents or reduced power consumption.
• Miniaturization: While this is a standard package, the industry pushes towards ever-smaller chip-scale package (CSP) LEDs for ultra-compact designs, though often at the expense of thermal performance and ease of handling.
• Improved Color Consistency: Advances in epitaxial growth and binning processes yield tighter distributions of wavelength and intensity, crucial for applications requiring uniform color appearance across multiple units.
• Integration: Beyond multi-chips in one package, there is a trend towards integrating the LED driver IC (constant current source, PWM controller) into the LED package itself, simplifying circuit design.
• Reliability & Robustness: Enhanced package materials and construction techniques improve resistance to thermal cycling, humidity, and mechanical stress, extending operational lifespans well beyond the traditional limits, making LEDs suitable for more demanding environments.

This particular component exemplifies the mature, cost-effective application of LED technology for standard indicator purposes, balancing performance, reliability, and manufacturability.