LTST-S326KGJRKT Dual-Color SMD LED Datasheet - Side-View - AlInGaP Green and Red - 30mA - Technical Documentation

1. Product Overview

This document provides the complete technical specifications for the LTST-S326KGJRKT, a surface-mount device (SMD) LED lamp. This component is a side-view, bicolor LED that integrates independent AlInGaP chips within a single compact package for emitting green and red light respectively. Designed for automated printed circuit board (PCB) assembly, it is well-suited for space-constrained applications in various consumer electronics and industrial electronic equipment.

1.1 Core Features and Advantages

LTST-S326KGJRKT provides several key advantages for modern electronic design:

• Dual-color light source:It integrates independent ultra-high brightness AlInGaP chips for emitting green and red light, controlled via separate pins (C1 for red light, C2 for green light).
• Side-view package:The main light is emitted from the side of the component, suitable for edge lighting, status indication in narrow spaces, and backlight applications where vertical mounting is not feasible.
• Manufacturing compatibility:Packaged in compliance with EIA standards and supplied on 8mm carrier tape in 7-inch reels, fully compatible with high-speed automatic placement equipment.
• Robust assembly process:Designed to withstand standard infrared (IR) reflow soldering processes, facilitating reliable surface-mount assembly.
• Environmental compliance:The device complies with the RoHS (Restriction of Hazardous Substances) directive.
• Electrical Compatibility:The device is compatible with integrated circuits and in many cases allows direct drive by a microcontroller or logic output.

1.2 Target Applications and Market

This LED is designed for various electronic devices requiring reliable and compact indicators, offering broad applicability. The main application areas include:

• Telecommunications equipment:Status indicators in cordless phones, mobile phones, and network system hardware.
• Computer and Office Automation:Backlighting for keyboards and keys in laptops and other portable devices; status lights on peripherals.
• Consumer Electronics and Home Appliances:Power, mode, or function indicator lights in various household devices.
• Industrial Equipment:Panel indicator lights, machine status lights, and control system feedback lights.
• Dedicated display:Suitable for micro displays, and as a light source for small-size signal and symbol illumination.

2. In-depth Technical Parameter Analysis

The following sections provide a detailed and objective interpretation of the key electrical, optical, and reliability parameters defined in the specification.

2.1 Absolute Maximum Ratings

These ratings define the stress limits that may cause permanent damage to the device. It is not recommended to operate at or near these limits during normal use. All ratings are specified at an ambient temperature (Ta) of 25°C.

• Power Dissipation (Pd):75 mW per chip. This is the maximum power that each LED chip can dissipate as heat. Exceeding this value may lead to excessive junction temperature, accelerating performance degradation or failure.
• Peak Forward Current (I_FP):80 mA, allowed only under pulse conditions (duty cycle 1/10, pulse width 0.1ms). This allows for brief, high-intensity flashing without causing overheating.
• Continuous Forward Current (I_F):30 mA DC. This is the recommended maximum current for continuous operation, balancing brightness and long-term reliability.
• Reverse Voltage (V_R):5 V. Applying a reverse bias voltage higher than this value may cause breakdown and damage the semiconductor junction.
• Operating and Storage Temperature:The device can operate at -30°C to +85°C and be stored at -40°C to +85°C. These ranges ensure functionality in most commercial and industrial environments.
• Soldering Thermal Limit:During IR reflow soldering, the package can withstand a peak temperature of up to 260°C for 10 seconds, which complies with the standard for lead-free assembly processes.

2.2 Electrical and Optical Characteristics

These are typical performance parameters measured under standard test conditions (Ta=25°C, unless noted, I_F=20mA). They define the expected behavior of the device in a circuit.

• Luminous intensity (I_V):The key metric for perceived brightness. For the green light chip, the typical value is 35.0 mcd (millicandela), ranging from 18.0 mcd (minimum) to 112.0 mcd (maximum). For the red light chip, the typical value is higher, at 45.0 mcd, with the same minimum/maximum range. The broad range necessitates the binning system described later.
• Viewing Angle (2θ_1/2):130 degrees (typical). This is the full angle at which the luminous intensity drops to half of its peak (axial) value. The wide 130° viewing angle is characteristic of side-view LEDs with a diffused lens, providing a broad emission pattern suitable for area lighting or wide-angle visibility.
• Forward Voltage (V_F):At 20mA, the typical value for both colors is 2.0 V, with a maximum of 2.4 V. Compared to some blue or white LEDs, this value is relatively low, simplifying the design of the drive circuit. The consistent V_Fallows the use of similar current-limiting resistor values when driving them individually.
• Peak Wavelength (λ_P) and Dominant Wavelength (λ_d):
  • Green Light:The peak wavelength is at 574 nm (typical), and the dominant wavelength is at 571 nm (typical). This places it within the pure green region of the spectrum.
  • Red Light:Peak wavelength is at 639 nm (typical), and dominant wavelength is at 631 nm (typical). This is a standard red, distinct from deep red or orange-red.
  Dominant wavelength is the perceived single wavelength of a color derived from the CIE chromaticity diagram.
• Spectral line half-width (Δλ):For green light, it is about 15 nm, and for red light, about 20 nm. This indicates spectral purity; a smaller value means the output is closer to monochromatic (purer color).
• Reverse current (I_R):Maximum 10 µA at 5V reverse bias, indicating high junction quality and low leakage current.

3. Binning System Description

To ensure consistency in mass production, LEDs are classified (binned) based on key optical parameters. The LTST-S326KGJRKT employs a two-dimensional binning system.

3.1 Luminous Intensity (Brightness) Binning

Green and red chips use the same binning method for luminous intensity at 20mA. The bin code defines the minimum and maximum brightness range. The tolerance within each bin is +/-15%.

• Bin Code M:18.0 – 28.0 mcd
• Bin Code N:28.0 – 45.0 mcd (covers typical value)
• Bin code P:45.0 – 71.0 mcd
• Bin code Q:71.0 – 112.0 mcd

Designers must select the appropriate bin based on the brightness required for their application. Using a higher bin (e.g., P or Q) ensures a higher minimum brightness but may incur additional cost.

3.2 Green Hue (Dominant Wavelength) Binning

Only green chips have specified hue (wavelength) binning to control color consistency. The tolerance for each bin is +/- 1 nm.

• Binning Code C:567.5 – 570.5 nm
• Bin code D:570.5 – 573.5 nm (including typical 571 nm)
• Bin code E:573.5 – 576.5 nm

The dominant wavelength of the red LED chip is specified only as a typical value (631 nm) in this datasheet, with no formal binning table. This indicates tighter process control or lower sensitivity to color shift in the application.

4. Performance Curve Analysis

Although specific graphical curves (e.g., Figure 1, Figure 5) are referenced in the datasheet, their general meaning is crucial for design.

4.1 Current-Voltage (I-V) Characteristics

Forward Voltage (V_F) has a positive temperature coefficient and also increases slightly with current. At 20mA, the typical V_Fis 2.0V, which is a key parameter for designing current-limiting circuits. Usually, a simple series resistor is sufficient: R = (V_{Power supply}- V_F) / I_F. Designers should use the maximum V_F(2.4V) to calculate the worst-case current to avoid overdriving the LED.

4.2 Relationship Between Luminous Intensity and Forward Current

Within the normal operating range, the light output (I_V) is approximately proportional to the forward current (I_F). Driving the LED with a current below 20mA will proportionally reduce the brightness. Operating above 20mA up to the maximum of 30mA will increase brightness, but will also increase power consumption and junction temperature, which may affect lifespan and cause a slight wavelength shift.

4.3 Temperature Dependence

Like all LEDs, the performance of AlInGaP chips is sensitive to temperature. As the junction temperature increases:

• Luminous intensity decreases:Light output decreases. The datasheet may show a derating curve.
• Forward voltage drop:Slightly reduced due to changes in the semiconductor bandgap.
• Wavelength shift:Typically, the dominant wavelength increases with temperature (shifting towards longer wavelengths). This is more pronounced in AlInGaP LEDs than in some other types. In critical applications, good thermal management on the PCB is essential for color stability.

5. Mechanical and Packaging Information

5.1 Package Dimensions and Polarity

The device employs a standard SMD package. Pin assignment is clearly defined: Cathode 1 (C1) for the red LED chip, Cathode 2 (C2) for the green LED chip. The anode may be common or internally connected per the package drawing; the drawing must be consulted for the exact layout. All critical dimensions are provided in millimeters with a standard tolerance of ±0.1 mm, ensuring reliable mounting and soldering.

5.2 Recommended PCB Pad Design

The datasheet includes the recommended PCB land pattern. Adhering to this design is crucial for achieving reliable solder joints, proper alignment, and managing heat dissipation during reflow soldering. The land pattern design accounts for solder fillet formation and prevents tombstoning (lifting of one end during reflow).

6. Soldering, Assembly and Operation Guide

6.1 IR Reflow Soldering Parameters

For lead-free assembly, the following reflow soldering profile is recommended:

• Preheat:150–200°C
• Preheat time:Maximum 120 seconds.
• Peak temperature:Maximum 260°C at component leads.
• Time above liquidus:The component shall not be exposed to peak temperature for more than 10 seconds. Reflow soldering should be performed a maximum of two times.

This profile complies with JEDEC standards, ensuring reliable solder joint formation while maintaining package integrity.

6.2 Manual Soldering (If Required)

If manual rework is required, use a soldering iron with a temperature not exceeding 300°C. Contact time with the pad should be limited to a maximum of 3 seconds and to a single operation only. Excessive heat or prolonged time may damage the plastic package or internal bond wires.

6.3 Cleaning

If post-soldering cleaning is required, use only the specified solvents. Immersing the LED in ethanol or isopropyl alcohol at room temperature for no more than one minute is acceptable. Unspecified or corrosive chemicals may damage the lens material or the encapsulating epoxy.

6.4 Storage and Moisture Sensitivity

LEDs are packaged in moisture barrier bags with desiccant. In this sealed state, they should be stored at ≤30°C and ≤90% relative humidity and used within one year. Once the original bag is opened, the devices have a Moisture Sensitivity Level of 3 (MSL3). This means they must be IR reflow soldered within one week after exposure to factory ambient conditions (≤30°C/60% RH). For storage longer than this after opening, they must be stored in a sealed container with desiccant or in a nitrogen environment. Devices exposed for more than one week require baking at 60°C for a minimum of 20 hours prior to soldering to remove absorbed moisture and prevent "popcorning" (package cracking due to vapor pressure during reflow).

6.5 Electrostatic Discharge (ESD) Precautions

AlInGaP LEDs are sensitive to electrostatic discharge. Proper ESD control measures must be taken during handling and assembly. This includes using grounded wrist straps, anti-static mats, and ensuring all equipment is properly grounded. ESD can cause immediate failure or latent damage, thereby shortening device lifetime.

7. Bayanin Kunshin da Oda

7.1 Ma'aunin Kaset da Reel

Components are supplied in embossed carrier tape wound on 7-inch (178 mm) diameter reels for automated assembly.

• Carrier Tape Width:8 mm.
• Quantity per Reel:3000 pcs.
• Minimum Order Quantity (MOQ):The remaining quantity is 500 pcs.
• Material bag coverage:Empty material bags are sealed with covering tape.
• Missing Parts:According to the packaging standard, a maximum of two consecutive missing LEDs is allowed.

Packaging conforms to ANSI/EIA-481 specification, ensuring compatibility with standard tape feeders on pick-and-place machines.

8. Application Design Considerations

8.1 Drive Circuit Design

Since the two colors have independent cathodes, they can be driven separately. For each channel, a simple constant current source or current limiting resistor is sufficient. Given the similar V_F, if driven from the same voltage rail, the same resistor value can typically be used for both colors, but separate calculations are recommended for precision. For multiplexing or PWM dimming, ensure the drive current and switching speed are within the device's ratings.

8.2 Thermal Management

Although the power consumption is low (maximum 75 mW per chip), effective thermal management on the PCB remains important for maintaining stable light output and long-term reliability, especially under high ambient temperatures or when driven at maximum continuous current. Ensure the PCB pads have sufficient thermal relief or are connected to a copper plane for heat dissipation.

8.3 Optical Integration

The side-view characteristics of this LED require careful mechanical design. Light guides, reflectors, or diffusers may be needed to direct light to the desired viewing area or to create uniform backlighting. The wide 130° viewing angle helps illuminate larger areas without creating hot spots.

9. Technical Comparison and Differentiation

LTST-S326KGJRKT distinguishes itself in the market through its specific combination of features:

• Comparison with Monochrome Side-View LEDs:It provides dual functionality within the same package size, saving PCB space and assembly time compared to installing two separate monochrome LEDs.
• Compared to top-view bicolor LEDs:The side-emitting characteristic is its primary differentiating factor, enabling use in unique mechanical designs where light must be emitted parallel to the PCB surface.
• Compared to other bicolor technologies:Both colors use AlInGaP technology, which provides high efficiency and good color saturation for red and green compared to older technologies such as GaP.
• Compared with RGB LED:This is a bicolor (red/green) device. It cannot produce blue or white light. It is selected for applications that specifically require only red and green indicators (e.g., power/status, run/warning signals).

10. Frequently Asked Questions (Based on Technical Parameters)

Q1: Can I drive the red and green LEDs simultaneously to produce yellow/orange?
A: Yes, by illuminating both chips simultaneously, the combined light output will be perceived as yellow or yellow-orange, depending on the relative intensity of each chip. The exact hue can be fine-tuned by adjusting the current ratio between the two channels.

Q2: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λ_P) is the wavelength at which the spectral power distribution is highest. Dominant wavelength (λ_d) is derived from CIE color coordinates and represents the wavelength of monochromatic light that appears to have the same color. λ_dMore relevant in terms of color specifications within the application.

Q3: Why does the binning system exist, and how do I specify which bin I need?
A: The binning system exists to account for natural variations in semiconductor manufacturing. It allows customers to select LEDs that meet their product's specific requirements for brightness and color consistency. When ordering, you must specify the required luminous intensity bin code (e.g., "N"), and for green LEDs, also specify the hue bin code (e.g., "D"), to ensure the received parts fall within these performance windows.

Q4: Does this LED require a heat sink?
A: N'ọnọdụ ọrụ nkịtị (I_F≤ 30mA, Ta ≤ 85°C), ọ naghị adịkarị mkpa iji heatsink pụrụ iche. Otú ọ dị, a na-atụ aro iji ezigbo nhazi okpomọkụ PCB - dịka iji zuru ezu ọla kọpa pad na traktị - iji belata okpomọkụ nkwonkwo dị ka o kwere mee, si otú a na-ebuli mmepụta ìhè na ndụ kacha elu.

11. Practical Application Examples

Example 1: Portable Device Status Indicator:In handheld medical devices, LEDs can be mounted on the edge of the main PCB. Green can indicate "Ready/Power On", red can indicate "Error/Low Battery", and both lit simultaneously can indicate "Standby/Charging". Side-emitting allows the light to be visible through a thin slit on the device housing.

Example 2: Industrial Control Panel Backlight:A series of such LEDs can be placed along the side of a translucent membrane switch panel. The side light is coupled into the panel material, providing uniform, low-glare backlighting for labels or symbols. Two colors can distinguish operating modes (e.g., green for automatic, red for manual).

12. Technical Principle Introduction

The LTST-S326KGJRKT uses aluminum indium gallium phosphide (AlInGaP) semiconductor material as its light-emitting chip. AlInGaP is a direct bandgap III-V compound semiconductor. By precisely controlling the ratios of aluminum, indium, and gallium, the material's bandgap energy can be tuned. When forward biased, electrons and holes recombine in the chip's active region, releasing energy in the form of photons. The wavelength (color) of these photons is determined by the bandgap energy: a larger bandgap produces a shorter wavelength (green), while a slightly smaller bandgap produces a longer wavelength (red). The device contains two such chips, fabricated with different material compositions, encapsulated within a reflective plastic package featuring a diffused lens that shapes the light output into a wide side-emitting pattern.

13. Industry Trends and Background

The development of such side-view SMD LEDs is driven by the ongoing miniaturization of electronic devices and the demand for more sophisticated user interfaces in smaller form factors. Trends influencing this product area include:

• Increased Integration:Transition from multiple discrete indicators to multi-chip, multi-color packaging to save space and simplify assembly.
• Higher efficiency:Continuous improvements in AlInGaP and InGaN (for blue/green light) epitaxial growth technology have led to higher luminous efficacy (more light output per watt of electrical power).
• The need for color consistency:Especificaciones de clasificación más estrictas y pruebas avanzadas a nivel de oblea se están volviendo cada vez más comunes para satisfacer las demandas de aplicaciones con requisitos críticos de coincidencia de color, como matrices de múltiples LED o señalización.
• Robustez en entornos adversos:Las mejoras en los materiales de encapsulado y las tecnologías de sellado han aumentado la confiabilidad frente a la humedad, los ciclos térmicos y la exposición química, ampliando su uso en aplicaciones automotrices y exteriores.

LTST-S326KGJRKT represents a mature, well-characterized solution in this evolving field, offering a reliable combination of bicolor functionality, side-view emission, and manufacturability.