LTST-C195KFKGKT Dual Color SMD LED Datasheet - Orange & Green - 20mA - English Technical Document

1. Product Overview

This document provides the complete technical specifications for a dual-color, surface-mount LED component. The device integrates two distinct light-emitting chips within a single industry-standard package, enabling the generation of orange and green light. It is designed for compatibility with automated assembly processes and modern soldering techniques, making it suitable for high-volume manufacturing applications in consumer electronics, indicators, and backlighting.

1.1 Key Features and Product Positioning

The primary features of this component include compliance with environmental regulations, utilization of high-brightness AlInGaP semiconductor technology for efficient light output, and packaging optimized for tape-and-reel automated placement. Its design is compatible with infrared (IR) and vapor phase reflow soldering processes, which are standard in surface-mount technology (SMT) assembly lines. The dual-color capability in a single package saves board space and simplifies design compared to using two separate single-color LEDs.

2. Technical Parameters: In-Depth Objective Interpretation

The following sections provide a detailed analysis of the device's electrical, optical, and thermal characteristics as defined in the specification sheet.

2.1 Absolute Maximum Ratings

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

• Power Dissipation (Pd): 75 mW per chip (Orange and Green). This is the maximum amount of power the LED can dissipate as heat at an ambient temperature (Ta) of 25°C. Exceeding this value risks thermal runaway and failure.
• Peak Forward Current (I_FP): 80 mA. This is the maximum allowable instantaneous forward current, typically specified under pulsed conditions (1/10 duty cycle, 0.1ms pulse width) to prevent excessive junction temperature rise.
• Continuous Forward Current (I_F): 30 mA DC. This is the maximum recommended current for continuous operation under normal conditions.
• Current Derating: 0.4 mA/°C linear from 25°C. As the ambient temperature rises above 25°C, the maximum allowable continuous forward current must be reduced by this factor to keep the junction temperature within safe limits.
• Reverse Voltage (V_R): 5 V. Applying a reverse bias voltage greater than this can cause breakdown and damage the LED junction.
• Operating & Storage Temperature: -30°C to +85°C and -40°C to +85°C, respectively. These define the environmental limits for reliable operation and non-operational storage.
• Soldering Temperature Limits: The device can withstand wave or IR soldering at 260°C for 5 seconds, and vapor phase soldering at 215°C for 3 minutes. These parameters are critical for defining the reflow profile during PCB assembly.

2.2 Electrical & Optical Characteristics

These parameters are measured at a standard test condition of Ta=25°C and I_F=20mA, unless otherwise noted. They define the typical performance of the device.

• Luminous Intensity (I_V):
  • Orange Chip: Minimum 45.0 mcd, Typical value unspecified, Maximum 280.0 mcd.
  • Green Chip: Minimum 18.0 mcd, Typical value unspecified, Maximum 71.0 mcd.

  The wide range between Min and Max indicates the device is available in different intensity bins (see Section 3). The orange chip is significantly brighter than the green chip at the same drive current.

• Viewing Angle (2θ_1/2): 130 degrees (typical) for both colors. This wide viewing angle indicates a diffuse lens type, suitable for applications requiring broad illumination rather than a focused beam.
• Wavelength:
  • Orange: Peak Wavelength (λ_P) ~611 nm, Dominant Wavelength (λ_d) ~605 nm.
  • Green: Peak Wavelength (λ_P) ~574 nm, Dominant Wavelength (λ_d) ~571 nm.

  Dominant wavelength is the perceived color by the human eye, derived from the CIE chromaticity diagram.

• Spectral Line Half-Width (Δλ): ~17 nm for Orange, ~15 nm for Green. This indicates the spectral purity or bandwidth of the emitted light.
• Forward Voltage (V_F): Typical 2.0V, Maximum 2.4V at 20mA for both colors. This low forward voltage is characteristic of AlInGaP technology and is important for calculating series resistor values and power consumption.
• Reverse Current (I_R): Maximum 10 µA at V_R=5V. This is the leakage current when the LED is reverse-biased.
• Capacitance (C): Typical 40 pF at 0V, 1MHz. This parameter can be relevant in high-frequency switching applications.

3. Binning System Explanation

The luminous intensity of the LEDs is sorted into bins to ensure consistency within a production lot. The bin code defines a specific intensity range.

3.1 Orange LED Intensity Bins

Intensity measured at I_F=20mA. Tolerance on each bin is +/-15%.

• Bin P: 45.0 - 71.0 mcd
• Bin Q: 71.0 - 112.0 mcd
• Bin R: 112.0 - 180.0 mcd
• Bin S: 180.0 - 280.0 mcd

3.2 Green LED Intensity Bins

Intensity measured at I_F=20mA. Tolerance on each bin is +/-15%.

• Bin M: 18.0 - 28.0 mcd
• Bin N: 28.0 - 45.0 mcd
• Bin P: 45.0 - 71.0 mcd

Designers should specify the required bin code when ordering to guarantee the desired brightness level in their application.

4. Performance Curve Analysis

The datasheet references typical characteristic curves which are essential for understanding device behavior under varying conditions. While the specific graphs are not reproduced here, their implications are analyzed.

4.1 Current vs. Voltage (I-V) Curve

The I-V curve for an LED is exponential. The typical V_F of 2.0V at 20mA provides a key operating point. The curve shows that a small increase in voltage beyond the knee point results in a large, potentially damaging, increase in current. This underscores the necessity of current-limiting methods (e.g., a series resistor or constant current driver).

4.2 Luminous Intensity vs. Forward Current

This curve is generally linear over a range. The luminous intensity is approximately proportional to the forward current. Driving the LED at the maximum continuous current (30mA) would yield higher brightness than the standard test condition of 20mA, but thermal management and lifetime considerations must be evaluated.

4.3 Temperature Dependence

LED performance is temperature-sensitive. The forward voltage (V_F) typically decreases with increasing junction temperature. More critically, luminous intensity degrades as temperature rises. The current derating specification (0.4 mA/°C) is a direct design constraint to manage this thermal effect and maintain reliability.

5. Mechanical & Package Information

The device conforms to an EIA standard surface-mount package footprint.

5.1 Pin Assignment

The dual-color LED has four pins (1, 2, 3, 4). According to the datasheet:

• Pins 1 and 3 are assigned to the Orange LED chip.
• Pins 2 and 4 are assigned to the Green LED chip.

This configuration typically implies a common-cathode or common-anode arrangement internally, which must be verified from the package outline drawing for correct circuit connection.

5.2 Package Dimensions and Tape & Reel

The device is supplied in 8mm tape on 7-inch diameter reels, compatible with automated pick-and-place machines. The tape and reel specifications follow ANSI/EIA 481-1-A-1994 standards. Key packaging details include:

• 4000 pieces per 7-inch reel.
• Minimum packing quantity for remainder parts is 500 pieces.
• A maximum of two consecutive missing components ("lamps") are allowed in the tape.

Suggested soldering pad dimensions are provided to ensure a reliable solder joint and proper alignment during reflow.

6. Soldering & Assembly Guidelines

6.1 Recommended Reflow Profiles

Two soldering profiles are suggested:

1. Standard IR Reflow Profile: For conventional tin-lead solder processes.
2. Lead-Free (Pb-Free) IR Reflow Profile: Must be used with Sn-Ag-Cu (SAC) solder paste. This profile typically has a higher peak temperature (e.g., 260°C) but a carefully controlled time above liquidus to prevent thermal damage to the LED's plastic lens and internal structure.

The absolute maximum condition is 260°C for 5 seconds for IR/wave soldering and 215°C for 3 minutes for vapor phase.

6.2 Storage and Handling Precautions

• Storage: Recommended not to exceed 30°C and 70% relative humidity. LEDs removed from their original moisture-barrier bag should be reflow-soldered within one week. For longer storage, they should be kept in a dry, sealed environment (e.g., with desiccant or in nitrogen) and baked at approximately 60°C for 24 hours before use to remove absorbed moisture and prevent "popcorning" during reflow.
• Cleaning: Only specified cleaning agents should be used. Isopropyl alcohol or ethyl alcohol at normal temperature for less than one minute is recommended. Unspecified chemicals may damage the LED package or lens.
• ESD Protection: LEDs are sensitive to electrostatic discharge. Proper ESD controls must be in place during handling: use grounded wrist straps, anti-static mats, ionizers to neutralize static on the lens, and ensure all equipment is properly grounded.

7. Application Suggestions

7.1 Typical Application Scenarios

This dual-color LED is suitable for a variety of indicator and status display applications, including but not limited to:

• Power/status indicators on consumer electronics (e.g., routers, chargers, appliances).
• Bi-color status lights (e.g., green for "on/ok," orange for "standby/warning").
• Backlighting for small icons or buttons.
• Automotive interior indicator lights (subject to appropriate qualification).
• Industrial equipment status panels.

7.2 Circuit Design Considerations

Drive Method: LEDs are current-driven devices. To ensure uniform brightness, especially when multiple LEDs are connected in parallel, a current-limiting resistor must be placed in series with each LED (Circuit Model A). Relying on the natural I-V characteristics to balance current in a parallel configuration without individual resistors (Circuit Model B) is not recommended, as small variations in V_F between LEDs can lead to significant differences in current and thus brightness.

The series resistor value (R_s) can be calculated using Ohm's Law: R_s = (V_supply - V_F) / I_F. Use the maximum V_F from the datasheet (2.4V) to ensure sufficient current under all conditions.

7.3 Thermal Management

While the power dissipation is low (75mW per chip), proper PCB layout can aid thermal performance. Ensure adequate copper area connected to the LED's thermal pads (if any) or surrounding the solder pads to act as a heat sink, especially when operating near maximum ratings or in high ambient temperatures.

8. Technical Comparison & Differentiation

The key differentiating factors of this component are its dual-color capability in a single SMD package and the use of AlInGaP technology for the orange emitter.

• vs. Single Color LEDs: Saves PCB space, reduces part count, and simplifies assembly compared to mounting two separate LEDs.
• AlInGaP vs. Other Technologies: AlInGaP (Aluminum Indium Gallium Phosphide) is known for high efficiency and stability in the red, orange, and yellow wavelength regions, often offering higher brightness and better temperature performance than older technologies like GaAsP.
• Wide Viewing Angle (130°): Offers a diffuse light pattern ideal for wide-area indication, as opposed to narrow-angle LEDs used for focused illumination.

9. Frequently Asked Questions (Based on Technical Parameters)

9.1 Can I drive this LED directly from a 5V or 3.3V microcontroller pin?

No, not directly. An LED requires current control. Connecting it directly to a voltage source like a MCU pin (which is typically current-limited but not designed for driving LEDs) can damage both the LED and the microcontroller output. Always use a series current-limiting resistor or a dedicated LED driver circuit.

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

Peak Wavelength (λ_P) is the wavelength at which the spectral power distribution is maximum. Dominant Wavelength (λ_d) is the single wavelength of monochromatic light that would match the perceived color of the LED, calculated from the CIE chromaticity coordinates. λ_d is more relevant for color specification in human-centric applications.

9.3 Why is the current derating necessary?

As ambient temperature increases, the LED junction temperature rises for a given operating current. Higher junction temperatures accelerate degradation mechanisms, reducing the LED's lifespan and potentially causing catastrophic failure. Derating the current lowers the power dissipation and thus the junction temperature, ensuring long-term reliability.

10. Practical Design Case Study

Scenario: Designing a dual-color status indicator for a device powered by a 5V rail. The indicator should show Green for "Normal Operation" and Orange for "Charging/Warning."

Design Steps:

1. Circuit Topology: Use two microcontroller GPIO pins. Each pin drives one color of the LED through a separate current-limiting resistor. Configure the internal connection (common anode/cathode) correctly based on the package drawing.
2. Resistor Calculation (for 20mA drive):
   • Assume V_F (max) = 2.4V, V_supply = 5V, I_F = 20mA.
   • R = (5V - 2.4V) / 0.020A = 130 Ohms.
   • Select the nearest standard value (e.g., 130Ω or 120Ω). A 120Ω resistor would yield a slightly higher current (~21.7mA), which is acceptable as it's below the 30mA maximum.
3. PCB Layout: Place the LED and its series resistors close together. Provide a modest amount of copper pour around the LED pads for heat dissipation. Follow the suggested soldering pad layout from the datasheet.
4. Software: Implement logic to turn on the Green GPIO for normal state and the Orange GPIO for warning state. Ensure they are not both on simultaneously unless a mixed color is desired, considering the drive current limits for the package.

11. Operational 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 and holes are injected into the active region where they recombine. The energy released during this recombination is emitted as photons (light). The specific wavelength (color) of the light is determined by the bandgap energy of the semiconductor material used in the active region. In this device, the orange light is produced by an AlInGaP chip, and the green light is produced by another chip (likely based on InGaN technology, though not explicitly stated here for green). The two chips are housed together in a single epoxy package with a diffuse lens that shapes the light output into a wide viewing angle.

12. Technology Trends

The field of LED technology continues to evolve with several clear trends relevant to components like this one:

• Increased Efficiency: Ongoing material science and chip design improvements lead to higher luminous efficacy (more light output per watt of electrical input), allowing for brighter indicators or lower power consumption.
• Miniaturization: The drive for smaller electronic devices pushes for LEDs in ever-smaller package footprints while maintaining or improving optical performance.
• Enhanced Reliability & Lifetime: Improvements in packaging materials, die attach methods, and phosphor technology (for white LEDs) continue to extend operational lifetimes and stability under harsh conditions.
• Integration: Beyond multi-color, there is a trend towards integrating control electronics (like constant current drivers or PWM controllers) directly with the LED die or within the package, creating "smart LED" modules that simplify system design.
• Environmental Compliance: The shift towards lead-free (Pb-free) soldering and halogen-free materials is now standard, as reflected in the separate soldering profiles provided in this datasheet.