LTL42FGYAD3HKPY Through Hole LED Lamp Datasheet - Yellow Green 569nm - 20mA - 52mW - English Technical Document

1. Product Overview

The LTL42FGYAD3HKPY is a Circuit Board Indicator (CBI) designed for straightforward integration into printed circuit board (PCB) assemblies. It consists of a black plastic right-angle housing that securely holds three yellow-green LED chips. This design is intended to provide a high-contrast visual indicator suitable for a variety of electronic equipment.

1.1 Core Advantages

• Ease of Assembly: The through-hole design and stackable housing format simplify the PCB assembly process.
• Enhanced Visibility: The black housing material increases the contrast ratio, making the illuminated LED more noticeable.
• Energy Efficiency: The device operates with low power consumption while delivering high luminous efficiency.
• Environmental Compliance: The product is lead-free and compliant with RoHS (Restriction of Hazardous Substances) directives.
• Specific Emission: Utilizes AlInGaP (Aluminum Indium Gallium Phosphide) technology to produce a consistent yellow-green light with a dominant wavelength of 569nm.

1.2 Target Applications

This LED lamp is suitable for a broad range of electronic applications, including but not limited to:

• Computer peripherals and status indicators
• Communication equipment
• Consumer electronics
• Industrial control panels and machinery

2. Technical Parameter Deep-Dive

The following section provides a detailed, objective interpretation of the key electrical, optical, and thermal parameters specified for the LTL42FGYAD3HKPY LED lamp. All data is referenced at an ambient temperature (TA) of 25°C unless otherwise stated.

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed.

• Power Dissipation (PD): 52 mW. This is the maximum amount of power the LED can dissipate as heat.
• Peak Forward Current (IFP): 60 mA. Permissible only under pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 10μs).
• DC Forward Current (IF): 20 mA. The recommended maximum continuous forward current for reliable operation.
• Operating Temperature Range (Topr): -30°C to +85°C. The ambient temperature range within which the device is designed to function.
• Storage Temperature Range (Tstg): -40°C to +100°C.
• Lead Soldering Temperature: 260°C for a maximum of 5 seconds, measured 2.0mm (0.079\") from the LED body.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters under specified test conditions.

• Luminous Intensity (Iv): 8.7 to 29 mcd (millicandela), with a typical value of 15 mcd at IF=10mA. Note that testing tolerance of ±30% is included in the guarantee.
• Viewing Angle (2θ1/2): 100 degrees. This is the full angle at which the luminous intensity drops to half of its axial (on-axis) value, indicating a relatively wide viewing cone.
• Peak Emission Wavelength (λP): 572 nm. The wavelength at which the spectral power distribution is maximum.
• Dominant Wavelength (λd): 569 nm (typical), ranging from 566 nm to 574 nm. This is the single wavelength perceived by the human eye that defines the color of the light.
• Spectral Line Half-Width (Δλ): 15 nm (typical). This parameter indicates the spectral purity or bandwidth of the emitted light.
• Forward Voltage (VF): 1.6V to 2.5V, with a typical value of 2.0V at IF=10mA.
• Reverse Current (IR): 10 μA maximum at a Reverse Voltage (VR) of 5V. It is critical to note that the device is not designed for reverse operation; this test condition is for characterization only.

3. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (Fig.1, Fig.6), their typical interpretations are provided here. These curves are essential for understanding device behavior under varying conditions.

3.1 Forward Current vs. Forward Voltage (I-V Curve)

The I-V characteristic is non-linear. The forward voltage (VF) has a specified range (1.6V-2.5V at 10mA). Designers must account for this variance when designing current-limiting circuits to ensure consistent brightness across multiple LEDs, especially when connected in parallel.

3.2 Luminous Intensity vs. Forward Current

Luminous intensity is approximately proportional to the forward current within the recommended operating range. Exceeding the maximum DC current (20mA) can lead to accelerated lumen depreciation and reduced operational lifetime.

3.3 Spectral Distribution

The spectral curve (referenced in Fig.1) would show a peak at approximately 572nm with a half-width of around 15nm, confirming the narrow-band yellow-green emission characteristic of AlInGaP technology.

3.4 Viewing Angle Pattern

The polar diagram (referenced in Fig.6) illustrates the 100-degree viewing angle, showing how light intensity is distributed spatially from the LED.

4. Mechanical & Packaging Information

4.1 Outline Dimensions

The device uses a black or dark gray plastic right-angle holder. The dimensional drawing provides critical measurements for PCB footprint design. Key notes include:

• All dimensions are in millimeters (with inch equivalents).
• Standard tolerance is ±0.25mm (±0.010\") unless a specific feature note states otherwise.
• The housing contains three yellow-green LEDs (LED1, LED2, LED3) with green diffused lenses.

4.2 Polarity Identification

For through-hole LEDs, polarity is typically indicated by lead length (the longer lead is the anode) and/or a flat spot or notch on the LED lens or housing flange. The PCB footprint should be designed to match this orientation.

4.3 Packing Specification

The datasheet includes a dedicated section for packing specifications, which would detail the reel, tube, or tray packaging format, quantities per package, and labeling information to ensure proper handling and inventory management.

5. Soldering & Assembly Guidelines

Adherence to these guidelines is crucial for maintaining reliability and preventing damage during the manufacturing process.

5.1 Storage Conditions

LEDs should be stored in an environment not exceeding 30°C and 70% relative humidity. If removed from their original moisture-barrier packaging, they should be used within three months. For longer storage outside the original bag, use a sealed container with desiccant or a nitrogen desiccator.

5.2 Cleaning

If cleaning is necessary, use alcohol-based solvents like isopropyl alcohol. Avoid harsh or unknown chemical cleaners.

5.3 Lead Forming

If leads need to be bent, this must be done before soldering and at normal room temperature. The bend should be made at least 3mm away from the base of the LED lens. Do not use the lens base or lead frame as a fulcrum during bending.

5.4 Soldering Process

Critical Rule: Maintain a minimum clearance of 2mm from the base of the lens/holder to the soldering point. Never immerse the lens or holder into solder.

• Hand Soldering (Iron): Maximum temperature 350°C, maximum time 3 seconds per lead (one time only).
• Wave Soldering: Pre-heat to a maximum of 120°C for up to 100 seconds. Solder wave temperature maximum 260°C for up to 5 seconds. The dipping position must be no lower than 2mm from the base of the epoxy lens.
• Important Note: IR reflow soldering is not suitable for this through-hole type LED lamp product. Excessive temperature or time can cause lens deformation or catastrophic failure.

5.5 PCB Assembly

During insertion into the PCB, use the minimum clinch force necessary to avoid imposing excessive mechanical stress on the LED leads or housing.

6. Application & Circuit Design Recommendations

6.1 Drive Method

LEDs are current-operated devices. To ensure uniform brightness when using multiple LEDs, it is strongly recommended to drive each LED with its own current-limiting resistor connected in series (Circuit Model A).

• Circuit Model A (Recommended): [Power Supply] -> [Resistor] -> [LED] -> [Ground]. This configuration compensates for the natural variance in forward voltage (VF) between individual LEDs, ensuring each receives the intended current.
• Circuit Model B (Not Recommended for Parallel): Connecting multiple LEDs directly in parallel with a single shared resistor (Circuit Model B) is discouraged. Small differences in the I-V characteristics of each LED can cause significant current imbalance, leading to visible differences in brightness and potential over-stress of the LED with the lowest VF.

6.2 Electrostatic Discharge (ESD) Protection

LEDs are susceptible to damage from electrostatic discharge. A robust ESD control program is essential in the handling and assembly environment.

• Personal Grounding: Operators should wear conductive wrist straps or anti-static gloves.
• Equipment Grounding: All tools, equipment, and workstations must be properly grounded.
• Static Neutralization: Use ionizers to neutralize static charge that may build up on the plastic lens surface due to handling friction.
• Area Control: Implement static-safe work areas with proper signage. Surfaces within these areas should measure less than 100V.
• Training: Ensure personnel are trained and certified in ESD prevention procedures.

7. Cautions & Reliability Considerations

7.1 Application Environment

This LED lamp is suitable for both indoor and outdoor signage applications, as well as standard electronic equipment. The operating temperature range of -30°C to +85°C supports use in various environments.

7.2 Thermal Management

While the device has a power dissipation rating, ensuring adequate heat sinking via the PCB traces and maintaining operation within the specified current and temperature limits is vital for long-term luminous output stability and lifetime.

7.3 Design Verification

Always prototype and verify the final design under expected operating conditions, including temperature extremes, to ensure performance meets application requirements. Account for the ±30% tolerance on luminous intensity in brightness-critical applications.

8. Technical Comparison & Differentiation

The LTL42FGYAD3HKPY offers specific advantages in its niche:

• Versus Single LED Lamps: The integration of three LEDs in one right-angle housing provides higher collective luminous output and potentially wider viewing coverage compared to a single discrete LED in a similar package.
• Versus SMD LEDs: The through-hole design offers superior mechanical strength and retention on the PCB, which can be advantageous in high-vibration environments or applications requiring frequent manual handling. It also simplifies prototyping and low-volume assembly.
• Color Specificity: The use of AlInGaP technology for 569nm yellow-green provides high color purity and efficiency for this specific wavelength, which may be preferable over filtered or phosphor-converted white LEDs for certain indicator applications requiring a precise color.

9. Frequently Asked Questions (FAQ)

9.1 Can I drive this LED at 20mA continuously?

Yes, 20mA is the maximum recommended DC forward current for continuous operation. For optimal longevity and reliability, operating at or slightly below this value (e.g., 15-18mA) is often advised.

9.2 Why is there a large range in luminous intensity (8.7 to 29 mcd)?

This range represents the minimum and maximum values specified in the datasheet, which includes an inherent ±30% testing tolerance. The typical value is 15 mcd. This variance is normal in LED manufacturing due to process variations. For consistent brightness in production, purchasing LEDs sorted into tighter luminous intensity bins is recommended.

9.3 What resistor value should I use for a 5V supply?

Using Ohm's Law (R = (Vsupply - VF_LED) / I_LED) and assuming a typical VF of 2.0V and a desired current of 10mA: R = (5V - 2.0V) / 0.01A = 300 Ohms. Always calculate using the maximum possible VF (2.5V) to ensure the minimum current is safe, and verify the resistor power rating (P = I^2 * R).

9.4 Is this LED suitable for automotive applications?

The operating temperature range (-30°C to +85°C) covers many automotive interior applications. However, automotive use typically requires qualification to specific standards (e.g., AEC-Q102) for reliability under harsh conditions like thermal cycling and humidity, which may not be covered by this general datasheet. Consult the manufacturer for automotive-grade variants.

10. Practical Design Case Study

Scenario: Designing a status indicator panel for an industrial router with multiple ports. Each port requires a clear, wide-angle yellow-green link/activity indicator.

Implementation:

1. Component Selection: The LTL42FGYAD3HKPY is chosen for its right-angle mounting (suitable for side-panel viewing), wide 100-degree viewing angle, and distinct yellow-green color.
2. Circuit Design: Each LED is driven independently from the router's 3.3V logic supply. Using the formula with max VF=2.5V and target IF=10mA: R = (3.3V - 2.5V) / 0.01A = 80 Ohms. A standard 82-ohm, 1/8W resistor is selected for each LED, connected in series as per Circuit Model A.
3. PCB Layout: The footprint is placed according to the mechanical drawing. Thermal relief is added to the pads to facilitate soldering. The 2mm clearance rule from the lens base is strictly observed in the solder mask and paste layer definitions.
4. Assembly: LEDs are inserted after all SMD components are placed. A wave soldering process is used with the specified profile (pre-heat <120°C, wave <260°C for <5s), ensuring the PCB is oriented so the LED bodies are not submerged.
5. Result: The panel provides uniform, highly visible indicators across all ports, with reliable operation in the equipment's operating environment of 0°C to 70°C.

11. Technology Principle Introduction

The LTL42FGYAD3HKPY utilizes AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material. When a forward voltage is applied across the p-n junction, electrons and holes recombine, releasing energy in the form of photons. The specific composition of the AlInGaP alloy is engineered to produce photons with a wavelength corresponding to yellow-green light (around 569nm). This direct-bandgap material is highly efficient at converting electrical energy into visible light, resulting in the high brightness and low power consumption noted in the features. The green diffused lens over the chip serves to scatter the light, helping to create the wide, uniform viewing angle characteristic of the device.

12. Industry Trends & Context

While surface-mount device (SMD) LEDs dominate high-volume production due to their small size and suitability for automated pick-and-place assembly, through-hole LEDs like the LTL42FGYAD3HKPY maintain relevance in several areas:

• Prototyping & Hobbyist Use: Their ease of hand-soldering and robust mechanical connection make them ideal for breadboards and prototype PCBs.
• High-Reliability/Industrial: The physical connection of a through-hole lead can be more resistant to mechanical shock and vibration than solder joints alone on an SMD part.
• Legacy Designs & Maintenance: Many existing products are designed with through-hole components, and replacement parts must maintain form-fit-function compatibility.
• Specific Form Factors: Right-angle holders and other specialized through-hole packages offer optical and mechanical solutions that may not be readily available or as cost-effective in SMD formats for certain applications, such as panel indicators where light needs to be directed parallel to the PCB.

The trend towards miniaturization and automation continues, but through-hole optoelectronics will likely persist in niches where their specific advantages in strength, thermal management (via leads), and design flexibility are paramount.