LTST-B32JEGBK-AT Ultra-Thin Full-Color SMD LED Datasheet - RGB Tri-Color - 0.65mm Ultra-Thin Height - 25mA/20mA Forward Current - Technical Documentation

1. Product Overview

LTST-B32JEGBK-AT is a compact full-color surface-mount LED, specifically designed for modern electronic applications that require vibrant color indication or backlighting in small form factors. This device integrates three distinct semiconductor chips within a single package: one AlInGaP chip for emitting red light and two InGaN chips for emitting green and blue light. This combination enables the generation of a wide color gamut through independent or combined control of the three primary color light sources. Its notable feature is an extremely low profile height of 0.65mm, making it suitable for applications with severe vertical space constraints, such as ultra-thin consumer electronics, wearable devices, or precision control panels.

The LED is supplied in 8mm carrier tape packaging, wound on 7-inch diameter reels, compliant with EIA standards, ensuring compatibility with high-speed automated pick-and-place equipment commonly used in high-volume manufacturing. Furthermore, it is compatible with lead-free infrared (IR) reflow soldering processes, adhering to contemporary environmental regulations and manufacturing standards.

1.1 Product Features

• Conforms to the RoHS (Restriction of Hazardous Substances) Directive.
• Ultra-thin package with a height of only 0.65mm.
• Utilizes efficient AlInGaP technology for red light and InGaN technology for green and blue light, achieving high luminous intensity.
• Packaged in 8mm carrier tape on 7-inch reels for easy automated operation.
• Complies with standard EIA package outlines.
• Design compatible integrated circuit (IC) drive levels.
• Suitable for automatic placement equipment.
• Can withstand standard infrared reflow soldering temperature profiles.

1.2 Application Fields

• Status and power indicator lights in telecommunications equipment, office automation equipment, home appliances, and industrial control systems.
• Backlighting of keyboards, keys, and control buttons.
• Illumination of miniature displays and symbol indicators.
• General-purpose signal lights requiring multi-color functionality.

2. Technical Parameters: In-depth and Objective Interpretation

The performance of the LTST-B32JEGBK-AT is defined by a comprehensive set of electrical, optical, and thermal parameters. Understanding these specifications is crucial for reliable circuit design and achieving the desired visual effects.

2.1 Absolute Maximum Ratings

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

• Power Dissipation (Pd):Red light: 62.5 mW, Green/Blue light: 76 mW. This parameter, combined with thermal resistance, determines the maximum allowable power to prevent overheating.
• Peak Forward Current (I_F(PEAK)):Red light: 60 mA, green/blue light: 100 mA. This is the maximum allowable pulse current, typically specified at a low duty cycle (1/10) and short pulse width (0.1ms), suitable for multiplexing or brief high-brightness pulses.
• DC forward current (I_F):Red light: 25 mA, green/blue light: 20 mA. This is the maximum continuous current recommended for reliable long-term operation.
• Electrostatic discharge (ESD) tolerance:Red: 2000V (HBM), Green/Blue: 1000V (HBM). InGaN chips for green and blue light are generally more sensitive to ESD than AlInGaP red chips, thus requiring stricter handling precautions.
• Operating and Storage Temperature:-40°C to +85°C (operating), -40°C to +90°C (storage). This defines the environmental conditions the device can withstand.
• Infrared welding conditions:Can withstand a peak temperature of 260°C for 10 seconds, which is the standard condition for lead-free reflow process.

2.2 Electrical and Optical Characteristics

These are typical and guaranteed performance parameters measured under standard test conditions (Ta=25°C, I_F=5mA, unless otherwise specified).

• Luminous intensity (I_V):is measured in millicandelas (mcd). The minimum values are: Red: 26.0 mcd, Green: 122.0 mcd, Blue: 22.0 mcd. The output of the green chip is significantly higher due to the high efficiency of the InGaN material at this wavelength and the peak sensitivity of the human eye in the green region.
• Viewing angle (2θ_1/2):The typical value is 120 degrees. This wide viewing angle indicates a Lambertian or near-Lambertian emission pattern, providing uniform brightness over a broad area.
• Peak Emission Wavelength (λ_P):Typical values: Red: 632 nm, Green: 518 nm, Blue: 468 nm. This is the wavelength at which the spectral power distribution reaches its maximum.
• Dominant Wavelength (λ_d):The single wavelength perceived by the human eye that defines a color. The specified ranges are: Red light: 616-628 nm, Green light: 519-537 nm, Blue light: 464-479 nm.
• Spectral Line Half-Width (Δλ):Typical values: Red light: 12 nm, Green light: 27 nm, Blue light: 20 nm. This indicates spectral purity; a smaller value means the light is more monochromatic. The red light spectrum from AlInGaP is typically narrower than the green/blue light from InGaN.
• Forward Voltage (V_F):At 5mA: Red: 1.50-2.15V, Green: 2.00-3.20V, Blue: 2.00-3.20V. The lower V_Fis a characteristic of AlInGaP technology compared to InGaN.
• Reverse Current (I_R):at V_RMaximum 10 μA at =5V. LED is not designed for reverse bias operation; this parameter is for quality test purposes only.

3. Bin System Description

To ensure color consistency and brightness matching in production, LEDs are sorted into different bins based on key optical parameters.

3.1 Luminous Intensity (Brightness) Binning

Kowane launi an raba shi zuwa matakai daban-daban (misali, A, B, C...). Ana auna ƙarfin haske a daidaitaccen ƙarfin kuzari na 5mA. Misali, matakin jan haske 'A' ya ƙunshi 26.0-31.0 mcd, yayin da matakin 'E' ya ƙunshi 54.0-65.0 mcd. Kore da shuɗi suna da nasu jadawalin bincike na kansu. Ana amfani da ƙimar sallamar +/-10% a cikin kowane mataki. Dole ne mai zane ya ƙayyade lambar binciken da ake buƙata, don tabbatar da daidaiton haske tsakanin sassa da yawa a cikin kayan aikin.

3.2 Hue (Dominant Wavelength) Binning

This binning ensures color consistency. LEDs are classified based on their dominant wavelength. For example, red LEDs are binned in 1 nm steps from 616-628 nm (bins 1-4). Green LEDs are binned from 519-537 nm (bins 1-6), and blue LEDs from 464-479 nm (bins 1-5). Each bin has a +/-1 nm tolerance. Specifying a hue bin is crucial in applications requiring precise color matching, such as multi-LED displays or status indicators where all red LEDs must appear identical.

4. Performance Curve Analysis

Although specific diagrams (Figure 1, Figure 5) are referenced in the specification, their meaning is standard.

• I-V curve:Forward Voltage (V_F) Increases with current (I_F) in a typical diode nonlinear, exponential manner. The curve for each chip color will differ due to the semiconductor material and bandgap.
• Luminous intensity vs. current:Within the normal operating range, light output is typically proportional to forward current, but at extremely high currents, efficiency may decrease due to thermal effects and efficiency droop.
• Spectral Distribution:Ensure the output spectrum of the red LED chip is single-peaked. The graph will show the relationship between relative radiant power and wavelength, indicating the peak wavelength (λ_P) and the spectral half-width (Δλ).
• Angular Distribution Diagram:The polar plot (Figure 5) illustrates the angular distribution of light intensity, confirming a 120-degree viewing angle where the intensity drops to half of its axial value.

5. Mechanical and Packaging Information

5.1 Package Dimensions and Pin Definitions

The device adheres to standard SMD package dimensions. Pin definitions are clear: Pin 2 is the cathode for the red chip, Pin 3 is the cathode for the green chip, and Pin 4 is the cathode for the blue chip. The common anode is most likely Pin 1 (inferred from standard RGB LED configuration). All dimensions are provided in millimeters, with a standard tolerance of ±0.1mm. The ultra-thin 0.65mm height is a key mechanical characteristic.

5.2 Recommended PCB Land Pattern

Pad pattern design is provided to ensure proper soldering and mechanical stability. Adhering to this recommended package outline is crucial for achieving reliable solder joints, preventing tombstoning, and ensuring correct alignment during reflow.

6. Soldering and Assembly Guide

6.1 Infrared Reflow Soldering Conditions (Lead-Free Process)

Recommended detailed reflow temperature profile. Key parameters include the preheat phase, specified time above liquidus, and a peak temperature not exceeding 260°C for a maximum of 10 seconds. This device is rated to withstand this profile a maximum of two times. For manual rework using a soldering iron, the tip temperature should not exceed 300°C, contact time per solder joint should be limited to within 3 seconds, and it should be performed only once.

6.2 Storage and Operation

• ESD Prevention Measures:Wrist straps, anti-static mats, and properly grounded equipment must be used, especially for ESD-sensitive green and blue light chips.
• Moisture Sensitivity Level (MSL):This device is rated MSL 3. After opening the original moisture barrier bag, if stored under conditions ≤30°C/60% RH, reflow soldering must be completed within 1 week. If stored outside the original bag for a longer period, baking at approximately 60°C for at least 20 hours is required before soldering to prevent "popcorn" effect during reflow.
• Cleaning:If post-solder cleaning is required, only alcohol-based solvents such as isopropyl alcohol or ethanol may be used. Immersion should be less than one minute at room temperature. Unspecified chemicals may damage the LED package or lens.

7. Packaging and Ordering Information

The LEDs are supplied in embossed carrier tape with a width of 8mm, wound on standard 7-inch (178mm) diameter reels. Each reel contains 4,000 pieces. The carrier tape is equipped with a cover tape to protect the components. Reels are typically packed three per inner box. The packaging complies with the ANSI/EIA-481 specification. The part number LTST-B32JEGBK-AT uniquely identifies this specific full-color, water-clear lens model.

8. Application Suggestions and Design Considerations

8.1 Typical Application Circuit

Each color channel (red, green, blue) must be driven independently. A current-limiting resistor must be connected in series with each anode pin to set the desired forward current and protect the LED. The resistor value is calculated using Ohm's Law: R = (V_{Power Supply}- V_F) / I_F. Since the V_Fof each color is different, even when using the same power supply voltage and the same drive current, three different resistor values are typically required. For precise current control or multiplexing multiple LEDs, it is recommended to use a dedicated LED driver IC or constant current source.

8.2 Thermal Management

Even though the power consumption is low, good thermal design on the PCB is very important for extending lifespan and maintaining stable light output. Ensure that the copper foil area connected to the thermal pad (if present) or the LED pad is sufficient to act as a heat sink, especially when operating near the maximum ratings or under high ambient temperatures.

8.3 Optical Design

Water clear lens provides a wide, diffuse light pattern. For applications requiring focused light or specific beam patterns, secondary optics (such as light guides, lenses, or diffusers) must be designed considering the LED's 120-degree viewing angle and the spatial separation of the three color chips within the package (which affects color mixing at close distances).

9. Technical Comparison and Differentiation

The primary differentiating factor of the LTST-B32JEGBK-AT is its achievement of a full RGB color gamut within an ultra-thin 0.65mm package height. Compared to older technologies using discrete monochrome LEDs or larger RGB packages, this device enables slimmer product designs. The use of AlInGaP for red light provides higher efficiency and better temperature stability compared to some other red LED technologies. Its compatibility with automated assembly and standard reflow processes reduces manufacturing complexity and cost compared to devices requiring manual soldering or special handling.

10. Frequently Asked Questions (Based on Technical Parameters)

10.1 Why is the maximum DC current different for red light (25mA) and green/blue light (20mA)?

This difference stems from inherent material properties and chip design. Under identical package thermal constraints, AlInGaP red chips can typically withstand slightly higher current densities than InGaN green and blue chips, resulting in a higher rated continuous current.

10.2 Can I use a single resistor on the common anode to drive all three colors?

No. Due to the different forward voltages (V_F) There is a significant difference. Connecting them in parallel with a single current-limiting resistor will cause severe current imbalance. The color with the lowest V_F(red light) will draw most of the current, potentially exceeding its rating, while other colors may be dim or not light up at all. Each color channel must have its own independent current-limiting mechanism.

10.3 What does "Bin Code" mean? Why is it important to specify it?

Due to manufacturing variations, LEDs are not identical. They are sorted (binned) after production based on measured luminous intensity and dominant wavelength. Specifying a binning code when ordering ensures you receive LEDs with nearly identical brightness and color. This is crucial for applications using multiple LEDs that require visual uniformity, such as backlight panels or multi-segment displays. Using LEDs from different bins can lead to noticeable differences in brightness or color.

11. Practical Design and Use Cases

Case: Designing Multi-Color Status Indicators for a Network Router
The designer required three status LEDs (power, internet, Wi-Fi), but there was only space for one LED on the PCB. Therefore, the LTST-B32JEGBK-AT was selected. The microcontroller drives each color independently: red for "power off/error," green for "normal operation," blue for "Wi-Fi activity," and combinations like cyan (green+blue) for other statuses. The 0.65mm height is suitable for the slim router housing. The designer specified strict chromaticity bins (e.g., green bin 2: 522-525nm) and mid-range luminous intensity bins to ensure consistent color and brightness across all manufactured units. The recommended reflow temperature profile was used during assembly, and the device passed all reliability tests.

12. Principle Introduction

Light emission in LEDs is based on the phenomenon of electroluminescence in semiconductor materials. When a forward voltage is applied across a p-n junction, electrons and holes are injected into the active region where they recombine. This recombination releases energy in the form of photons (light). The color (wavelength) of the emitted light is determined by the bandgap energy of the semiconductor material. The bandgap of AlInGaP (Aluminum Indium Gallium Phosphide) corresponds to red and amber-orange light. InGaN (Indium Gallium Nitride) has a wider, tunable bandgap, enabling emission across the spectrum from ultraviolet to blue and green light. Full-color functionality is achieved by integrating chips of these different materials into a single package.

13. Development Trends

The development trend for SMD LEDs used in indicator lights and backlighting continues towards higher efficiency (more light output per watt), smaller package sizes, and lower profile heights to enable thinner end products. Efforts are also being made to improve color rendering and consistency. Furthermore, integrating control electronics (such as drivers or PWM circuits) into the LED package itself is an ongoing development direction to simplify system design. The use of advanced materials and Chip Scale Package (CSP) technology may further push the limits of miniaturization and performance.