LTL42FYYGHKPRY LED Lamp Datasheet - Yellow & Yellow-Green - 20mA - 52mW - English Technical Document

1. Product Overview

The LTL42FYYGHKPRY is a through-hole LED lamp designed for circuit board indication. It utilizes a black plastic right-angle holder (housing) that mates with the LED components. This design is part of a Circuit Board Indicator (CBI) family, offering ease of assembly and a variety of mounting configurations, including top-view and right-angle orientations, which can be stacked for array applications.

1.1 Core Advantages

• Ease of Assembly: The design is optimized for straightforward circuit board assembly processes.
• Enhanced Contrast: The black housing material provides a high contrast ratio, improving the visibility of the emitted light.
• Energy Efficiency: Features low power consumption and high luminous efficiency.
• Environmental Compliance: This is a lead-free product and is compliant with RoHS (Restriction of Hazardous Substances) directives.
• Chip Technology: Utilizes AlInGaP semiconductor technology for the yellow (569nm, 589nm) and yellow-green LEDs, offering stable and bright output.

1.2 Target Applications

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

• Computer systems and peripherals
• Communication devices
• Consumer electronics
• Industrial equipment and controls

2. Technical Parameter Deep Dive

This section provides a detailed, objective analysis of the key electrical, optical, and thermal parameters specified for the LTL42FYYGHKPRY LED lamp.

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation at or near these limits is not recommended for extended periods.

• Power Dissipation (Pd): 52 mW (for both yellow and yellow-green LEDs). This parameter indicates the maximum power the LED can dissipate as heat at an ambient temperature (TA) of 25°C.
• Peak Forward Current (I_F(PEAK)): 60 mA. This is the maximum allowable pulsed forward current, with strict conditions: duty cycle ≤ 1/10 and pulse width ≤ 10μs. Exceeding this can cause immediate junction failure.
• DC Forward Current (I_F): 20 mA. This is the recommended maximum continuous forward current for reliable long-term operation.
• Operating Temperature Range: -40°C to +85°C. The device is designed to function within this ambient temperature range.
• Storage Temperature Range: -45°C to +100°C. The device can be stored safely within these limits when not in operation.
• Lead Soldering Temperature: 260°C for a maximum of 5 seconds, measured 2.0mm (0.079\") from the LED body. This is critical for wave or hand soldering processes to prevent thermal damage to the epoxy lens or internal die bonds.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters measured at TA=25°C and I_F=10mA, unless otherwise stated. They define the expected behavior of the device under normal operating conditions.

• Luminous Intensity (I_V): A measure of the perceived power of light emitted in a specific direction.
  • Yellow LEDs (LED1, LED2): Typical value is 14 mcd, with a range from 3.8 mcd (Min) to 30 mcd (Max). Testing tolerance is ±15%.
  • Yellow-Green LED (LED3): Typical value is 15 mcd, with a range from 8.7 mcd (Min) to 29 mcd (Max). Testing tolerance is ±15%.
• Viewing Angle (2θ_1/2): 100 degrees for all LEDs. This is the full angle at which the luminous intensity is half of the intensity at 0° (on-axis). A 100° angle indicates a relatively wide, diffused emission pattern suitable for status indication.
• Peak Emission Wavelength (λ_P): The wavelength at which the spectral emission is strongest.
  • Yellow LEDs: 591 nm.
  • Yellow-Green LED: 572 nm.
• Dominant Wavelength (λ_d): The single wavelength that best represents the perceived color of the light, derived from the CIE chromaticity diagram.
  • Yellow LEDs: Typical 588 nm, range 584-594 nm. Testing tolerance is ±1 nm.
  • Yellow-Green LED: Typical 570 nm, range 566-574 nm. Testing tolerance is ±1 nm.
• Spectral Line Half-Width (Δλ): 15 nm for all LEDs. This indicates the spectral purity; a smaller value means a more monochromatic color.
• Forward Voltage (V_F): The voltage drop across the LED when conducting the specified forward current.
  • Typical value is 2.0V for all LEDs, with a maximum of 2.6V at I_F=10mA.
• Reverse Current (I_R): Maximum 10 μA at a Reverse Voltage (V_R) of 5V. Important Note: This device is not designed for reverse-bias operation. This test condition is for characterization only.

3. Binning System Explanation

To ensure color and brightness consistency in production, LEDs are sorted into bins based on key parameters. The LTL42FYYGHKPRY uses separate binning for luminous intensity and dominant wavelength.

3.1 Luminous Intensity Binning

LEDs are categorized by their measured luminous intensity at I_F=10mA.

3.1.1 Yellow LEDs (LED1, LED2)

• Bin 3ST: 3.8 - 6.5 mcd
• Bin 3UV: 6.5 - 11 mcd
• Bin 3WX: 11 - 18 mcd
• Bin 3YX: 18 - 30 mcd

Tolerance for each bin limit is ±15%.

3.1.2 Yellow-Green LED (LED3)

• Bin L3: 8.7 - 12.6 mcd
• Bin L2: 12.6 - 19 mcd
• Bin L1: 19 - 29 mcd

Tolerance for each bin limit is ±15%.

3.2 Dominant Wavelength (Hue) Binning

LEDs are sorted by their precise color point, defined by the dominant wavelength.

3.2.1 Yellow LEDs (LED1, LED2)

• Bin H15: 584.0 - 586.0 nm
• Bin H16: 586.0 - 588.0 nm
• Bin H17: 588.0 - 590.0 nm
• Bin H18: 590.0 - 592.0 nm
• Bin H19: 592.0 - 594.0 nm

Tolerance for each bin limit is ±1 nm.

3.2.2 Yellow-Green LED (LED3)

• Bin H06: 566.0 - 568.0 nm
• Bin H07: 568.0 - 570.0 nm
• Bin H08: 570.0 - 572.0 nm
• Bin H09: 572.0 - 574.0 nm

Tolerance for each bin limit is ±1 nm.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (Typical Electrical/Optical Characteristics Curves on pages 5-6), their implied relationships are critical for design.

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

The relationship is exponential. For a typical V_F of 2.0V at 10mA, slight increases in current will cause a corresponding increase in voltage. A constant current driver is essential to maintain stable light output and prevent thermal runaway, as the LED's forward voltage has a negative temperature coefficient.

4.2 Luminous Intensity vs. Forward Current

Luminous intensity is approximately proportional to the forward current in the normal operating range (up to 20mA). However, efficiency may drop at higher currents due to increased junction temperature. Operating at the typical 10mA provides a good balance of brightness and longevity.

4.3 Temperature Dependence

LED performance is temperature-sensitive.

• Luminous Intensity: Typically decreases as junction temperature increases.
• Forward Voltage (V_F): Decreases with increasing temperature (negative temperature coefficient).
• Dominant Wavelength: Can shift slightly with temperature, affecting perceived color.

5. Mechanical & Packaging Information

5.1 Outline Dimensions

The datasheet includes detailed mechanical drawings. Key notes from the drawing:

• All dimensions are in millimeters (inches are also provided).
• Standard tolerance is ±0.25mm (0.010\") unless otherwise specified.
• The holder (housing) material is black or dark gray plastic.
• LED1 and LED2 are yellow with a yellow diffused lens. LED3 is yellow-green with a green diffused lens.

5.2 Polarity Identification

For through-hole LEDs, the cathode is typically identified by a flat spot on the lens, a shorter lead, or other marking as shown in the dimensional drawing. Correct polarity must be observed during PCB assembly.

6. Soldering & Assembly Guidelines

Adherence to these guidelines is crucial for reliability and to prevent damage during manufacturing.

6.1 Lead Forming

• Bending must be done before soldering, at room temperature.
• The bend should be at least 3mm away from the base of the LED lens.
• Do not use the base of the lead frame as a fulcrum.
• Apply minimum clinch force during PCB insertion to avoid mechanical stress.

6.2 Soldering Parameters

A minimum clearance of 2mm must be maintained between the solder point and the base of the lens/holder. The lens/holder must not be dipped into solder.

6.2.1 Soldering Iron

• Temperature: 350°C Maximum.
• Time: 3 seconds Maximum per joint (one time only).

6.2.2 Wave Soldering

• Pre-heat Temperature: 120°C Max.
• Pre-heat Time: 100 seconds Max.
• Solder Wave Temperature: 260°C Max.
• Soldering Time: 5 seconds Max.

Critical Warning: Excessive temperature or time can deform the lens or cause catastrophic failure. IR reflow soldering is not suitable for this through-hole type LED product.

6.3 Storage Conditions

• Recommended storage ambient: ≤ 30°C and ≤ 70% relative humidity.
• LEDs removed from their original, moisture-barrier packaging should be used within three months.
• For longer storage outside original packaging, store in a sealed container with desiccant or in a nitrogen ambient desiccator.

6.4 Cleaning

If cleaning is necessary, use alcohol-based solvents such as isopropyl alcohol.

7. Application Notes & Design Considerations

7.1 Drive Method

LEDs are current-operated devices. To ensure consistent luminous intensity and color, and to prevent damage, they must be driven by a constant current source or with a current-limiting resistor in series with a voltage source. The design should be based on the maximum DC forward current (20mA) and typical forward voltage (2.0V).

7.2 Thermal Management

Although power dissipation is low (52mW), ensuring adequate airflow or heat sinking in high-density layouts or high ambient temperatures helps maintain performance and lifespan by keeping the junction temperature within safe limits.

7.3 Optical Considerations

The 100-degree viewing angle and diffused lens provide wide, even illumination suitable for panel indicators. The black housing minimizes stray light and improves contrast. For applications requiring specific beam patterns, secondary optics may be needed.

8. Technical Comparison & Differentiation

While a direct comparison requires specific competitor data, key differentiators of this product based on its datasheet include:

• Dual-Color Array in Single Package: The integration of two yellow and one yellow-green LED in a single, stackable housing allows for compact multi-status indication.
• Wide Operating Temperature Range: -40°C to +85°C suitability for industrial and automotive environments where many consumer-grade LEDs may not perform reliably.
• Strict Binning with Tolerances: The defined binning for both intensity (±15%) and wavelength (±1nm) allows for precise color and brightness matching in production runs, reducing the need for post-assembly calibration.
• Robust Mechanical Design: The right-angle holder is designed for ease of assembly and provides physical protection for the LED elements.

9. Frequently Asked Questions (Based on Technical Parameters)

Q1: Can I drive this LED at 20mA continuously?
A1: Yes, 20mA is the maximum recommended DC forward current for continuous operation. For optimal longevity and to account for variations, designing for a typical current of 10-15mA is often advisable.

Q2: What resistor value should I use with a 5V supply?
A2: Using Ohm's Law: R = (V_supply - V_F) / I_F. For a typical V_F of 2.0V and a target I_F of 10mA: R = (5V - 2.0V) / 0.01A = 300 Ω. Use the nearest standard value (e.g., 330 Ω for slightly less current). Always calculate using the maximum V_F (2.6V) to ensure current does not exceed limits under worst-case conditions.

Q3: Why is there a peak current rating (60mA) much higher than the DC rating?
A3: The peak current rating is for very short pulses (≤10μs) at a low duty cycle (≤10%). This allows for applications like multiplexing or brief overdrive for brighter flashing signals, but the average power and junction temperature must remain within limits to avoid damage.

Q4: Can I use reflow soldering for this LED?
A4: No. The datasheet explicitly states \"IR reflow is not suitable process for through-hole type LED lamp product.\" Only wave soldering or hand soldering with an iron, following the specified time/temperature profiles, should be used.

10. Design-in Case Study

Scenario: Designing a multi-status indicator panel for an industrial controller.
The panel needs to show Power (steady yellow), Activity (blinking yellow), and Fault (steady yellow-green). Using the LTL42FYYGHKPRY:

• Layout: A single 3-LED package saves PCB space compared to three discrete LEDs.
• Drive Circuit: Three separate current-limiting resistor circuits are designed from a common 3.3V rail. Calculations use V_F(max)=2.6V and I_F=10mA, resulting in R = (3.3V-2.6V)/0.01A = 70 Ω (use 68 Ω standard).
• Control: A microcontroller's GPIO pins, capable of sourcing/sinking 10mA, directly drive the LEDs through the resistors. The \"Activity\" LED is pulsed using a timer interrupt, staying within the peak current specs for the short pulse.
• Thermal: The low total power (3 * ~20mW = 60mW) requires no special heatsinking on the standard FR4 PCB.
• Result: A compact, reliable, and clearly distinguishable multi-status indicator that meets the industrial temperature range requirement.

11. Technology Principle Introduction

The LTL42FYYGHKPRY utilizes Aluminium Indium Gallium Phosphide (AlInGaP) semiconductor material for its light-emitting region. When a forward voltage is applied, electrons and holes recombine within the semiconductor's p-n junction, releasing energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy, which directly dictates the wavelength (color) of the emitted light—yellow (~589nm) and yellow-green (~570nm) in this case. The diffused epoxy lens encapsulates the semiconductor die, providing environmental protection, mechanical stability, and shaping the light output into a wide viewing angle. The right-angle plastic holder provides a standardized mechanical interface for PCB mounting and aids in light direction.

12. Industry Trends & Context

While through-hole LEDs like the LTL42FYYGHKPRY remain vital for prototyping, repair, and certain industrial applications requiring robust mechanical connections, the broader industry trend is strongly towards surface-mount device (SMD) LEDs. SMD packages enable higher automation, smaller form factors, and better thermal performance for high-power applications. However, through-hole components offer advantages in mechanical strength, ease of hand assembly, and visibility in certain panel designs. The continued development of through-hole LEDs focuses on improving efficiency, color consistency (through tighter binning), and reliability under harsh conditions (wider temperature ranges, resistance to thermal shock during soldering). The integration of multiple dice or colors in a single package, as seen here, is a response to the need for space-saving and functional integration even in traditional form factors.