LTLR42FGAFEH79Y LED Lamp Datasheet - Yellow-Green & Orange - 20mA/10mA - 52mW - English Technical Document

1. Product Overview

The LTLR42FGAFEH79Y is a Circuit Board Indicator (CBI) module, integrating multiple LED lamps within a black plastic right-angle housing. This design is specifically engineered for straightforward assembly onto printed circuit boards (PCBs). The product combines solid-state lighting technology with a user-friendly mechanical package.

1.1 Core Advantages

• Ease of Assembly: The right-angle holder is designed for simplified circuit board mounting and is stackable for creating arrays.
• Enhanced Contrast: The black housing material improves the visual contrast ratio of the illuminated LEDs.
• Energy Efficiency: Utilizes low-power consumption, high-efficiency LED chips.
• Environmental Compliance: This is a lead-free product compliant with RoHS directives.
• Reliable Source: Features solid-state light sources for long operational life.

1.2 Target Applications

This component is suitable for a wide range of electronic equipment requiring status indication, including but not limited to:

• Communication devices
• Computer systems and peripherals
• Consumer electronics
• Home appliances

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

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

• Power Dissipation (PD): 52 mW for both Yellow-Green and Orange LEDs.
• Peak Forward Current (IFP): 60 mA (pulse condition: duty cycle ≤1/10, pulse width ≤0.1ms).
• Continuous DC Forward Current (IF): 20 mA.
• Operating Temperature Range: -40°C to +85°C.
• Storage Temperature Range: -40°C to +100°C.
• Lead Soldering Temperature: 260°C maximum for 5 seconds, measured 2.0mm from the LED body.

2.2 Electrical & Optical Characteristics

Characteristics are measured at TA=25°C. The test conditions differ between the LED types.

• Luminous Intensity (Iv):
  • Yellow-Green (LED1, IF=20mA): Typical 80 mcd, ranging from 23 mcd (Min) to 140 mcd (Max).
  • Orange (LED3/4, IF=10mA): Typical 65 mcd, ranging from 30 mcd (Min) to 140 mcd (Max).
• Viewing Angle (2θ1/2): 100 degrees for both LED types, providing a wide illumination pattern.
• Peak Emission Wavelength (λP): Approximately 571 nm for Yellow-Green and 611 nm for Orange LEDs.
• Dominant Wavelength (λd):
  • Yellow-Green: 569 nm (Typ), range 565-571 nm.
  • Orange: 605 nm (Typ), range 598-613.5 nm.
• Spectral Line Half-Width (Δλ): ~15 nm for Yellow-Green, ~17 nm for Orange.
• Forward Voltage (VF):
  • Yellow-Green: 2.1V (Typ), range 1.6-2.6V at 20mA.
  • Orange: 1.9V (Typ), range 1.4-2.5V at 10mA.
• Reverse Current (IR): 10 μA maximum at a reverse voltage (VR) of 5V. Important: The device is not designed for operation in reverse bias; this parameter is for test purposes only.

3. Binning System Explanation

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

3.1 Yellow-Green LED (LED1) Binning

Luminous Intensity Bins (@20mA):

• AB: 23 - 50 mcd
• CD: 50 - 85 mcd
• EF: 85 - 140 mcd
• Tolerance: ±15% on bin limits.

Dominant Wavelength Bins (@20mA):

• Bin 1: 565.0 - 568.0 nm
• Bin 2: 568.0 - 571.0 nm
• Tolerance: ±1 nm on bin limits.

3.2 Orange LED (LED3, LED4) Binning

Luminous Intensity Bins (@10mA):

• AB: 30 - 50 mcd
• CD: 50 - 85 mcd
• EF: 85 - 140 mcd
• Tolerance: ±30% on bin limits.

Dominant Wavelength (Hue) Bins (@10mA):

• H22: 598.0 - 600.0 nm
• H23: 600.0 - 603.0 nm
• H24: 603.0 - 606.0 nm
• H25: 606.0 - 610.0 nm
• H26: 610.0 - 613.5 nm
• Tolerance: ±1 nm on bin limits.

4. Performance Curve Analysis

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

4.1 Relative Luminous Intensity vs. Forward Current

These curves show the relationship between the drive current and the light output for both LED colors. They demonstrate the super-linear region of operation and are critical for determining the appropriate current for a desired brightness level, ensuring efficiency and longevity.

4.2 Forward Voltage vs. Forward Current

These IV curves are vital for designing the current-limiting circuitry. The curves show the typical voltage drop across the LED at various currents, allowing engineers to calculate necessary series resistor values or design constant-current driver circuits accurately.

4.3 Spectral Distribution

While not graphed in detail, the specified peak and dominant wavelengths, along with spectral half-width, define the color purity of the emitted light. The yellow-green LED emits in the ~571 nm region, while the orange LED emits in the ~611 nm region, providing distinct visual indicators.

5. Mechanical & Packaging Information

5.1 Outline Dimensions

The component features a right-angle through-hole design. Key dimensional notes include:

• All primary dimensions are in millimeters.
• Standard tolerance is ±0.25mm unless otherwise specified.
• The housing material is black plastic rated UL94-V0 for flame retardancy.
• LED1 (Yellow-Green) uses a white diffused lens. LED3 and LED4 (Orange) use an orange diffused lens.

5.2 Polarity Identification

Polarity is typically indicated by the physical structure of the housing (e.g., flat side on the lens or pin length). The datasheet's outline drawing should be consulted to identify the cathode and anode leads for correct installation.

6. Soldering & Assembly Guidelines

6.1 Storage Conditions

• Sealed Package: Store at ≤30°C and ≤70% RH. Use within one year of packing.
• Opened Package: Store at ≤30°C and ≤60% RH. Components should undergo IR reflow soldering within 168 hours (1 week) of opening the moisture barrier bag (MBB).
• Extended Storage: For storage beyond 168 hours, bake at 60°C for at least 48 hours before soldering to prevent moisture-induced damage (\"popcorning\") during reflow.

6.2 Lead Forming

• Bend leads at a point at least 3mm away from the base of the LED lens.
• Do not use the LED body or lead frame base as a fulcrum during bending.
• Perform all lead forming operations at room temperature and before the soldering process.

6.3 PCB Assembly & Soldering

• Apply minimal clinching force during PCB insertion to avoid mechanical stress on the LED.
• Hand soldering with a temperature-controlled iron is applicable for this through-hole component, adhering to the maximum 260°C for 5 seconds limit.
• For cleaning, use alcohol-based solvents like isopropyl alcohol if necessary.

7. Packaging & Ordering Information

7.1 Packing Specification

The product is supplied in standard packaging suitable for automated or manual assembly. The exact reel, tube, or tray configuration (e.g., quantity per reel) is defined in the packing specification section of the datasheet.

7.2 Part Number Interpretation

The part number LTLR42FGAFEH79Y follows an internal coding system that identifies the product family, package type, LED configuration, and likely the bin codes for luminous intensity and wavelength.

8. Application Notes & Design Considerations

8.1 Typical Application Circuits

These LEDs require a current-limiting device when powered from a voltage source. A simple series resistor is the most common method. 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 forward voltage, and IF is the desired forward current (20mA for Yellow-Green, 10mA for Orange). Always ensure the resistor's power rating is sufficient.

8.2 Thermal Management

Although power dissipation is low (52mW), maintaining the LED junction temperature within the specified range is crucial for longevity and stable light output. Ensure adequate spacing and possible airflow in high-density layouts, especially when operating near the maximum ambient temperature of 85°C.

8.3 Optical Design

The 100-degree viewing angle provides a wide beam. For applications requiring more focused light, external lenses or light pipes can be used. The black housing minimizes internal reflections and improves off-state contrast.

9. Technical Comparison & Differentiation

The LTLR42FGAFEH79Y offers specific advantages in its class:

• Multi-LED Integration: Combines different color LEDs (Yellow-Green and Orange) in a single, easy-to-mount package, saving board space and assembly time compared to using discrete LEDs.
• Right-Angle Design: The housing allows the light to be emitted parallel to the PCB surface, which is ideal for edge-lit panels or status indicators viewed from the side.
• Stackable Housing: The mechanical design permits stacking multiple units to form vertical or horizontal arrays cleanly.
• Clear Binning: Well-defined intensity and wavelength bins allow for precise color and brightness matching in production runs.

10. Frequently Asked Questions (FAQ)

10.1 Can I drive the Orange LED (LED3/4) at 20mA?

The Absolute Maximum Rating specifies a continuous DC forward current of 20mA for all LEDs. However, the Optical Characteristics are specified at IF=10mA for the Orange LEDs. Driving them at 20mA will produce higher luminous intensity but may exceed the typical values listed and could affect long-term reliability. It is recommended to follow the test condition (10mA) for guaranteed optical performance.

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

Peak Wavelength (λP) is the wavelength at which the emission spectrum has its maximum intensity. Dominant Wavelength (λd) is a colorimetric quantity derived from the CIE chromaticity diagram; it represents the single wavelength of the monochromatic light that would appear to have the same color as the LED's output to the human eye. λd is often more relevant for color specification.

10.3 Why is the storage and handling moisture sensitivity so important?

LED packages can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can rapidly vaporize, creating internal pressure that may delaminate the package or crack the die (\"popcorning\"). The MSL3 (Moisture Sensitivity Level 3) rating and associated baking requirements are critical process controls to prevent this failure mode.

11. Practical Design Case Study

Scenario: Designing a multi-status indicator panel for a network router. The panel needs a power-on indicator (steady green), an activity indicator (blinking yellow-green), and a fault indicator (steady orange).

Implementation: A single LTLR42FGAFEH79Y module can be used. The Yellow-Green LED (LED1) can serve as the activity indicator, driven by a microcontroller pin with PWM for blinking. One of the Orange LEDs (e.g., LED3) can be the fault indicator. A separate green LED would be needed for the power indicator. The right-angle housing allows the panel to be mounted perpendicular to the main PCB, directing light towards the user. The designer must calculate appropriate current-limiting resistors for each LED based on the microcontroller's GPIO voltage (e.g., 3.3V) and the LED's VF at the desired current.

12. Operational Principle

Light Emitting Diodes (LEDs) are semiconductor devices that emit light through electroluminescence. When a forward voltage is applied across the p-n junction, electrons recombine with holes, releasing energy in the form of photons. The specific color of the light is determined by the energy bandgap of the semiconductor material used. The Yellow-Green LED uses an AllnGaP (Aluminum Indium Gallium Phosphide) chip, while the Orange LED uses an AIInGaP chip, with slight variations in material composition altering the bandgap and thus the emitted wavelength.

13. Technology Trends

The field of indicator LEDs continues to evolve. Trends include:

• Increased Efficiency: Ongoing material science improvements yield higher luminous efficacy (more light output per electrical watt), allowing for lower current operation and reduced system power consumption.
• Miniaturization: While through-hole packages remain popular for robustness, there is a parallel trend towards smaller surface-mount device (SMD) packages for high-density boards.
• Integrated Solutions: Growth in multi-chip packages and modules with built-in current limiting resistors or even driver ICs, simplifying circuit design further.
• Color Consistency: Advances in epitaxial growth and binning processes continue to improve the consistency of color and brightness across production batches, which is critical for aesthetic and functional applications.