Rectangular Amber-Yellow LED Bar LTL-6201KY Datasheet - AlInGaP Technology - English Technical Document

1. Product Overview

The LTL-6201KY is a solid-state light source designed as a rectangular bar display. Its primary function is to provide a large, bright, and uniform emitting area for applications requiring clear visual indicators. The device is built using advanced AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology, specifically configured to produce an amber-yellow light output. This technology, grown on a transparent GaAs (Gallium Arsenide) substrate, contributes to its efficiency and color purity. The product is housed in a standard dual-in-line package (DIP), making it compatible with various mounting techniques, including panel and legend mounting, which broadens its applicability in different electronic assemblies and user interfaces.

1.1 Core Advantages and Target Market

The device offers several key advantages that make it suitable for a range of industrial, commercial, and consumer applications. Its large and bright light-emitting area ensures high visibility, which is critical for status indicators, backlighting for legends and panels, and general illumination in confined spaces. The low power requirement aligns with modern energy-efficient design principles, while the excellent on-off contrast ratio ensures the indicator is clearly distinguishable between its active and inactive states. The wide viewing angle is a significant benefit for applications where the indicator may be viewed from various positions, not just head-on. The inherent solid-state reliability of LED technology means the device offers long operational life, resistance to shock and vibration, and consistent performance over time. The primary target markets include industrial control panels, instrumentation, consumer electronics, automotive interior lighting, and any application requiring a robust, reliable, and bright indicator light.

2. In-Depth Technical Parameter Analysis

A thorough understanding of the device's specifications is essential for proper integration into a circuit design. The parameters define the operational boundaries and expected performance under specific conditions.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. They are not intended for normal operation.

• Power Dissipation per Chip: 75 mW. This is the maximum amount of power that can be dissipated as heat by each individual LED chip within the package without causing degradation.
• Peak Forward Current per Chip: 100 mA. This is the maximum instantaneous forward current allowed, but only under pulsed conditions with a 1/10 duty cycle and a 0.1 ms pulse width. Exceeding this, even briefly, can cause catastrophic failure.
• Continuous Forward Current per Chip: 25 mA at 25°C. This is the recommended maximum current for continuous DC operation. A derating factor of 0.33 mA/°C is applied for ambient temperatures (Ta) above 25°C. For example, at 50°C, the maximum continuous current would be approximately 25 mA - (0.33 mA/°C * 25°C) = 16.75 mA.
• Reverse Voltage per Chip: 5 V. Applying a reverse bias voltage exceeding this value can break down the LED's PN junction.
• Operating & Storage Temperature Range: -35°C to +85°C. The device can function and be stored within this ambient temperature range.
• Solder Temperature: Maximum 260°C for a maximum of 3 seconds, measured 1.6mm (1/16 inch) below the seating plane. This is critical for wave soldering or reflow processes to prevent package damage.

2.2 Electrical & Optical Characteristics (at Ta=25°C)

These are the typical performance parameters measured under specified test conditions, providing the expected behavior during normal operation.

• Average Luminous Intensity (Iv): Minimum 43 mcd, Typical 109 mcd at a forward current (IF) of 10 mA. This parameter is categorized, meaning devices are binned or sorted based on their measured light output. It is measured using a sensor and filter that mimics the human eye's photopic response (CIE curve).
• Peak Emission Wavelength (λp): 595 nm (nanometers) at IF=20 mA. This is the wavelength at which the optical power output is at its maximum.
• Spectral Line Half-Width (Δλ): 15 nm at IF=20 mA. This indicates the spectral purity or the spread of the emitted light's wavelengths. A smaller value indicates a more monochromatic (pure color) light.
• Dominant Wavelength (λd): 592 nm at IF=20 mA. This is the single wavelength that best represents the perceived color of the light by the human eye, which for this device is in the amber-yellow region.
• Forward Voltage (VF): Minimum 2.05 V, Typical 2.6 V at IF=20 mA. This is the voltage drop across the LED when it is conducting the specified current. It is crucial for designing the current-limiting circuitry.
• Reverse Current (IR): Maximum 100 µA at a reverse voltage (VR) of 5 V. This is the small leakage current that flows when the device is reverse-biased at its maximum rating.

3. Binning System Explanation

The datasheet explicitly states that the luminous intensity is \"categorized.\" This refers to a common industry practice known as binning. During manufacturing, there are natural variations in the performance of semiconductor devices. To ensure consistency for the end-user, LEDs are tested after production and sorted into different groups, or \"bins,\" based on key parameters. For the LTL-6201KY, the primary binned parameter is Luminous Intensity (Iv). The datasheet provides a range (43-109 mcd at 10mA), but in production, devices would be grouped into tighter sub-ranges (e.g., 43-55 mcd, 56-70 mcd, etc.). This allows designers to select parts with a known, consistent brightness level for their application, which is vital for products requiring uniform appearance across multiple indicators. While not explicitly detailed in this brief datasheet, other common binning parameters for colored LEDs can include forward voltage (VF) and dominant wavelength (λd) to ensure color consistency.

4. Performance Curve Analysis

While the provided datasheet excerpt mentions \"Typical Electrical / Optical Characteristic Curves,\" the specific graphs are not included in the text. Typically, such curves for an LED like the LTL-6201KY would include:

• Forward Current vs. Forward Voltage (I-V Curve): This non-linear curve shows the relationship between the current flowing through the LED and the voltage across it. It is essential for designing the driver circuit, as a small change in voltage can cause a large change in current.
• Luminous Intensity vs. Forward Current: This graph shows how the light output increases with increasing drive current. It is typically linear over a range but will saturate at higher currents, and excessive current leads to efficiency drop and accelerated aging.
• Luminous Intensity vs. Ambient Temperature: This curve demonstrates the derating of light output as the junction temperature of the LED increases. Higher temperatures generally reduce light output and can shift the wavelength slightly.
• Spectral Distribution: A plot showing the relative intensity of light emitted across the wavelength spectrum, centered around the peak wavelength of 595nm with a defined half-width.

Designers must consult the full datasheet with these graphs to understand the device's behavior under non-standard conditions (different currents, temperatures) and to optimize performance and reliability.

5. Mechanical and Packaging Information

5.1 Package Dimensions and Drawing

The device uses a rectangular, dual-in-line package. The dimensional drawing provides critical measurements for PCB (Printed Circuit Board) layout, including the overall length, width, and height of the package, the spacing between pins (pitch), the pin diameter, and the position of the light-emitting window. The note specifies that all dimensions are in millimeters, with a standard tolerance of ±0.25 mm (0.01 inches) unless otherwise noted. Accurate adherence to these dimensions is necessary for proper fitment in panel cutouts and on the PCB.

5.2 Pin Connection and Polarity Identification

The LTL-6201KY has 8 pins. The pinout is as follows: 1-Cathode A, 2-Anode A, 3-Anode B, 4-Cathode B, 5-Cathode D, 6-Anode D, 7-Anode C, 8-Cathode C. This configuration suggests the rectangular bar contains multiple LED chips (likely four, labeled A, B, C, D) arranged in a specific circuit. The internal circuit diagram, though not detailed here, would show how these anodes and cathodes are connected internally. Correct polarity is paramount; connecting an LED in reverse bias will prevent it from lighting and, if the reverse voltage rating is exceeded, can destroy the device. The package likely has a physical marker (a notch, a dot, or a beveled edge) to identify Pin 1.

6. Soldering and Assembly Guidelines

The absolute maximum rating section provides the key parameter for soldering: the body temperature must not exceed 260°C for more than 3 seconds. This is a standard rating for many through-hole components. For wave soldering, the conveyor speed and preheat temperature must be controlled to meet this limit. For manual soldering, a temperature-controlled iron should be used, and contact time with the pin should be minimized. It is recommended to solder no closer than 1.6mm from the plastic body to prevent thermal damage. After soldering, the device should be allowed to cool naturally. Proper ESD (Electrostatic Discharge) handling procedures should be followed during all assembly stages to prevent damage to the sensitive semiconductor junction.

7. Application Suggestions and Design Considerations

7.1 Typical Application Scenarios

• Industrial Control Panels: Status indicators for machinery, power on/off, fault alarms, and mode selection.
• Instrumentation: Backlighting for switches, scales, and dials on test equipment.
• Consumer Electronics: Power indicators, function status lights (e.g., record, play, mute) on audio/video equipment.
• Automotive Interiors: Illumination for dashboard switches, gear shift indicators, or general cabin lighting (where color and brightness are suitable).
• Legends and Panels: Backlighting for engraved or printed labels on front panels, providing a professional, evenly lit appearance.

7.2 Critical Design Considerations

• Current Limiting: An LED is a current-driven device. A series current-limiting resistor is mandatory when driving from a voltage source to set the operating point (e.g., 10mA or 20mA as per datasheet) and prevent thermal runaway. The resistor value is calculated using Ohm's Law: R = (V_source - VF_LED) / I_desired.
• Thermal Management: Although low-power, the derating curve for continuous current must be respected. In high ambient temperature environments or enclosed spaces, the effective current must be reduced to prevent exceeding the junction temperature limits, which affects light output and lifespan.
• Viewing Angle: The wide viewing angle is beneficial but must be considered in the mechanical design. Light may spill into adjacent areas, which could be desirable or require light guides/baffles to control.
• Binning for Consistency: For applications with multiple indicators, specifying a tight luminous intensity bin from the supplier is recommended to ensure uniform brightness across the product.

8. Technical Comparison and Differentiation

The LTL-6201KY's primary differentiator is its use of AlInGaP technology for amber-yellow light. Compared to older technologies like standard GaAsP (Gallium Arsenide Phosphide) LEDs, AlInGaP offers significantly higher luminous efficiency, meaning more light output for the same electrical input power. It also provides better color stability over temperature and lifetime, and a more saturated, pure color due to its narrower spectral half-width. The rectangular bar form factor with a large emitting area and DIP packaging makes it distinct from smaller, point-source LEDs (like 3mm or 5mm round LEDs) and surface-mount device (SMD) alternatives, offering easier handling for through-hole assembly and potentially better heat dissipation via its longer leads.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED at 30mA for more brightness?
A: The maximum continuous current rating is 25mA at 25°C. Operating at 30mA exceeds this rating, which will increase junction temperature, reduce efficiency, and significantly shorten the device's lifespan. It is not recommended.

Q: The forward voltage is listed as \"2.05V min, 2.6V typ.\" Which value should I use for my circuit calculation?
A: For a robust design, use the maximum typical value (2.6V) to ensure sufficient voltage headroom. If you use the minimum (2.05V) and get a device with a higher VF, your circuit may not provide enough current to achieve the desired brightness.

Q: What does \"categorized for light output\" mean for my order?
A: It means you can request devices from a specific brightness range (bin). If your application requires consistent brightness across multiple units, you should consult the supplier's detailed binning document and specify the desired Iv bin code when ordering.

Q: Can I connect the four internal LED chips in series?
A: The internal circuit diagram is needed to confirm. The given pinout suggests independent anodes and cathodes for chips A, B, C, D. This typically allows for individual control or wiring in various series/parallel combinations, but the configuration must be verified against the diagram to avoid short circuits.

10. Practical Design and Usage Case

Scenario: Designing a status panel for a network router with four indicator lights (Power, Internet, Wi-Fi, Ethernet).
The LTL-6201KY is selected for its bright, uniform amber light and wide viewing angle. A 5V supply rail is available on the PCB. Targeting a forward current of 15mA (a compromise between brightness and power consumption), and using a typical VF of 2.4V, the current-limiting resistor value is calculated: R = (5V - 2.4V) / 0.015A = 173.3 Ohms. A standard 180 Ohm resistor is chosen. Four identical circuits are built, one for each LED. The LEDs are mounted behind a front panel with laser-etched legends. Because the LEDs are binned for consistent intensity, all four indicators appear equally bright to the user. The wide viewing angle ensures the status is visible even when the router is placed on a low shelf.

11. Technology Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor devices that emit light through a process called electroluminescence. When a forward voltage is applied across the PN junction of the semiconductor material (in this case, AlInGaP), electrons from the N-type region recombine with holes from the P-type region in the depletion zone. This recombination releases energy in the form of photons (light particles). The specific wavelength (color) of the emitted light is determined by the energy bandgap of the semiconductor material. AlInGaP has a bandgap that corresponds to light in the red, orange, amber, and yellow parts of the visible spectrum. The use of a transparent GaAs substrate allows more of the generated light to escape the chip, improving overall light extraction efficiency compared to absorbing substrates.

12. Technology Development Trends

The trend in indicator LED technology continues towards higher efficiency, greater reliability, and more compact packaging. While through-hole DIP packages like the LTL-6201KY remain relevant for certain applications requiring high power handling or ease of manual assembly, the industry has largely shifted to Surface-Mount Device (SMD) packages (e.g., 0603, 0805, PLCC) for automated PCB assembly, saving space and cost. For colored LEDs, AlInGaP technology for red-amber-yellow and InGaN (Indium Gallium Nitride) for blue-green-white have become dominant due to their superior performance. Future developments may focus on even higher efficiency (more lumens per watt), improved color rendering for white LEDs, and the integration of control electronics (like constant current drivers) within the LED package itself (\"smart LEDs\"). However, the fundamental principles of reliability, clear datasheet specifications, and proper thermal and electrical design remain constant and critical for successful implementation.