SMD LED LTST-G683GEBW Datasheet - 3.2x2.8x1.9mm Package - 2.8V/3.8V Forward Voltage - 20mA/30mA Current - RGB Colors - English Technical Documentation

1. Product Overview

The LTST-G683GEBW is a surface-mount device (SMD) LED designed for automated printed circuit board (PCB) assembly. Its miniature size makes it suitable for space-constrained applications across a broad spectrum of electronic equipment. The device integrates three distinct LED chips within a single package: a green InGaN chip, a red AlInGaP chip, and a blue InGaN chip, each with independent electrical connections. This configuration allows for individual control of each color, enabling status indication, symbol illumination, and front-panel backlighting functions.

1.1 Core Features

• Compliant with RoHS environmental directives.
• Packaged in 8mm tape on 7-inch diameter reels for automated pick-and-place assembly.
• Standard EIA package footprint ensures compatibility with industry-standard placement equipment.
• Integrated Circuit (I.C.) compatible drive characteristics.
• Designed to withstand infrared (IR) reflow soldering processes.
• Preconditioned to JEDEC Moisture Sensitivity Level 3 (MSL 3).

1.2 Target Applications

• Telecommunication equipment (cordless/cellular phones).
• Office automation devices and notebook computers.
• Network systems and home appliances.
• Indoor signboards and status indicators.
• Signal and symbol luminaires.

2. Technical Parameters Deep Dive

2.1 Absolute Maximum Ratings

All ratings are specified at an ambient temperature (Ta) of 25°C. Exceeding these values may cause permanent damage.

• Power Dissipation: 80 mW (Green/Blue), 72 mW (Red).
• Peak Forward Current (1/10 Duty Cycle, 0.1ms Pulse): 100 mA (Green/Blue), 80 mA (Red).
• DC Forward Current: 20 mA (Green/Blue), 30 mA (Red).
• Operating Temperature Range: -40°C to +85°C.
• Storage Temperature Range: -40°C to +100°C.

2.2 Electrical & Optical Characteristics

Measured at Ta=25°C with a forward current (IF) of 20mA, unless otherwise noted.

• Luminous Intensity (Iv):
  • Green: Min 900 mcd, Typ 2240 mcd (Max).
  • Red: Min 355 mcd, Typ 900 mcd (Max).
  • Blue: Min 180 mcd, Typ 355 mcd (Max).
• Luminous Flux (Φv): Typical values are 3.5 lm (Green), 2.1 lm (Red), 0.9 lm (Blue).
• Viewing Angle (2θ1/2): Typically 120 degrees.
• Peak Wavelength (λP): Typical values are 518 nm (Green), 630 nm (Red), 465 nm (Blue).
• Dominant Wavelength (λd):
  • Green: 520-530 nm.
  • Red: 617-629 nm.
  • Blue: 465-475 nm.
• Spectral Half-Width (Δλ): Typical values are 35 nm (Green), 20 nm (Red), 25 nm (Blue).
• Forward Voltage (VF):
  • Green/Blue: Min 2.8V, Max 3.8V.
  • Red: Min 1.8V, Max 2.4V.
• Reverse Current (IR): Maximum 10 μA at VR=5V. The device is not designed for reverse bias operation.

3. Binning System Explanation

The product is classified into bins based on luminous intensity and dominant wavelength to ensure color and brightness consistency in production.

3.1 Luminous Intensity Binning

Intensity is binned using a two-character code (e.g., A1, B4, D12). The first letter (A-D) defines the green intensity range, while the number (1-12) defines the corresponding red and blue intensity ranges. Each bin has a tolerance of ±11%.

• Green Intensity Groups: A (900-1120 mcd), B (1120-1400 mcd), C (1400-1800 mcd), D (1800-2240 mcd).
• Red/Blue Intensity Sub-groups: Numbers 1-12 map to specific minimum and maximum values for red and blue LEDs as detailed in the cross-table.

3.2 Dominant Wavelength Binning

Wavelength is binned using codes E1 through E4, with a tolerance of ±1 nm per bin.

• E1: Green 520-525 nm, Red 617-629 nm, Blue 465-470 nm.
• E2: Green 520-525 nm, Red 617-629 nm, Blue 470-475 nm.
• E3: Green 525-530 nm, Red 617-629 nm, Blue 465-470 nm.
• E4: Green 525-530 nm, Red 617-629 nm, Blue 470-475 nm.

4. Performance Curve Analysis

The datasheet includes typical characteristic curves which are essential for circuit design.

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

This curve shows the nonlinear relationship between the applied forward voltage and the resulting current for each color chip. Designers use this to select appropriate current-limiting resistors. The red LED typically has a lower forward voltage (~2.0V) compared to the green and blue LEDs (~3.2V).

4.2 Luminous Intensity vs. Forward Current

This graph illustrates how light output increases with drive current. It is generally linear within the recommended operating range but may saturate at higher currents. This helps in determining the required drive current to achieve a desired brightness level.

4.3 Spectral Distribution

While not explicitly graphed, the specified peak wavelength and spectral half-width define the emission spectrum for each color. The green and blue LEDs, based on InGaN, have broader spectral widths (~25-35 nm) compared to the red AlInGaP LED (~20 nm).

5. Mechanical & Package Information

5.1 Package Dimensions

The device conforms to a standard SMD footprint. Key dimensions (in millimeters) are: Length: 3.2 mm, Width: 2.8 mm, Height: 1.9 mm. Tolerances are typically ±0.2 mm.

5.2 Pin Assignment & Polarity

The 6-pad package has the following independent anode/cathode connections:

• Pins 1 & 6: Blue LED.
• Pins 2 & 5: Red LED.
• Pins 3 & 4: Green LED.

Proper polarity must be observed during PCB layout.

5.3 Recommended PCB Pad Design

A land pattern diagram is provided to ensure reliable soldering. The pad design accounts for thermal relief and proper solder fillet formation during reflow.

6. Soldering & Assembly Guide

6.1 IR Reflow Soldering Profile

A lead-free soldering profile is recommended, compliant with J-STD-020B.

• Pre-heat: 150-200°C for a maximum of 120 seconds.
• Peak Temperature: Maximum 260°C.
• Time Above Liquidus: As per the profile curve.
• Soldering Limit: Maximum of two reflow cycles, 10 seconds peak time each.

6.2 Storage Conditions

• Sealed Bag (MSL 3): Store at ≤30°C and ≤70% RH. Use within one year of bag opening.
• After Bag Opening: Store at ≤30°C and ≤60% RH. Complete IR reflow within 168 hours (1 week).
• Extended Storage (Opened): Use sealed containers with desiccant. If stored >168 hours, bake at 60°C for 48+ hours before soldering.

6.3 Cleaning

If cleaning is necessary, use alcohol-based solvents like isopropyl alcohol or ethyl alcohol. Immerse the LED at normal temperature for less than one minute. Avoid unspecified chemical cleaners.

7. Packaging & Ordering Information

7.1 Tape and Reel Specifications

The LEDs are supplied in embossed carrier tape.

• Tape Width: 8 mm.
• Reel Diameter: 7 inches.
• Quantity per Reel: 2000 pieces.
• Minimum Order Quantity (MOQ): 500 pieces for remnants.
• Packaging complies with EIA-481-1-B specifications.

8. Application Suggestions

8.1 Typical Application Circuits

Each color channel requires a series current-limiting resistor. The resistor value (R) can be calculated using Ohm's Law: R = (Vcc - VF) / IF, where Vcc is the supply voltage, VF is the LED's forward voltage, and IF is the desired forward current (e.g., 20mA). Separate resistors for each color are mandatory due to their different VF characteristics.

8.2 Design Considerations

• Thermal Management: Ensure the PCB layout provides adequate thermal dissipation, especially when driving multiple LEDs or at high ambient temperatures.
• ESD Protection: Although not explicitly stated as sensitive, standard ESD handling precautions for semiconductors are recommended during assembly.
• Optical Design: The diffused lens provides a wide viewing angle (120°). For directed light, secondary optics may be required.

9. Technical Comparison & Differentiation

The LTST-G683GEBW offers a compact, integrated RGB solution. Key differentiators include:

• Integrated Tri-Color: Combines three discrete colors in one 3.2x2.8mm footprint, saving board space compared to three separate LEDs.
• Independent Control: Separate anodes/cathodes allow for individual dimming and color mixing, unlike common-anode or common-cathode RGB LEDs.
• High Brightness: Offers high luminous intensity bins, particularly for green, suitable for applications requiring high visibility.
• Process Compatibility: Fully compatible with high-volume, automated SMT assembly and lead-free reflow processes.

10. Frequently Asked Questions (FAQ)

10.1 Can I drive the red LED at 30mA and the green/blue at 20mA simultaneously?

Yes, the Absolute Maximum Ratings specify a DC forward current of 30mA for the red LED and 20mA for the green/blue LEDs. You must design your driver circuit to provide these specific currents to each channel. Exceeding the rated current will reduce lifetime and may cause failure.

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

Peak Wavelength (λP) is the wavelength at which the optical output power is maximum. Dominant Wavelength (λd) is derived from the CIE chromaticity diagram and represents the single wavelength of a monochromatic light that would appear to have the same color to the human eye. λd is more relevant for color perception in applications.

10.3 How do I interpret the bin code A7 or D12?

The bin code ensures color and brightness matching. For example, code "A7" means the green LED's intensity is in bin "A" (900-1120 mcd), and the red & blue LEDs' intensities correspond to sub-group "7" (see cross-table for exact min/max values for red and blue). Always specify the required bin codes for consistent production runs.

11. Practical Design Case Study

Scenario: Designing a multi-status indicator for a networking device. The indicator must show Power (Green), Activity (Flashing Blue), and Fault (Red). Implementation: Use the LTST-G683GEBW. Connect each color channel to a GPIO pin of a microcontroller via a current-limiting resistor. Calculate resistors: For a 5V supply, R_Green/Blue ≈ (5V - 3.2V) / 0.02A = 90Ω (use 91Ω standard). R_Red ≈ (5V - 2.0V) / 0.02A = 150Ω. The firmware can then independently control each LED for steady, blinking, or mixed-color states, all within a single, tiny footprint.

12. Operating Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light when an electric current passes through them. This phenomenon is called electroluminescence. In the LTST-G683GEBW:

• The Green and Blue chips use Indium Gallium Nitride (InGaN) semiconductor material. The bandgap energy of the InGaN active layer determines the emitted color (green or blue).
• The Red chip uses Aluminium Indium Gallium Phosphide (AlInGaP) material, which is optimized for high-efficiency red and amber emission.
• When forward-biased, electrons and holes recombine in the active region, releasing energy in the form of photons (light). The diffused epoxy lens encapsulates the chip, provides mechanical protection, and shapes the light output beam.

13. Technology Trends

The SMD LED market continues to evolve towards:

• Higher Efficiency: Increasing lumens per watt (lm/W) to provide more light output for the same electrical input, reducing power consumption and thermal load.
• Miniaturization: Development of even smaller package sizes (e.g., 2.0x1.6mm, 1.6x0.8mm) for ultra-compact consumer electronics.
• Improved Color Rendering & Consistency: Tighter binning tolerances and new phosphor technologies for more precise and stable color points, critical for display backlighting and architectural lighting.
• Integrated Smart Features: Trend towards LEDs with built-in drivers, controllers, or communication interfaces (like I2C) to simplify system design.

Devices like the LTST-G683GEBW represent the established mainstream technology offering a reliable, cost-effective multi-color solution for general indicator applications.