LTL-R42FGYYHKP LED Lamp Datasheet - Through Hole - Yellow Green & Yellow - 10mA - 2.0V - English Technical Document

1. Product Overview

The LTL-R42FGYYHKP is a through-hole mount LED lamp designed as a Circuit Board Indicator (CBI). It consists of a black plastic right-angle housing that integrates multiple LED chips. The primary function of this component is to provide clear, high-contrast status or indicator lighting on electronic circuit boards. Its design prioritizes ease of assembly and reliable performance in a variety of electronic applications.

1.1 Core Advantages

• Ease of Assembly: The design is optimized for straightforward placement and soldering onto printed circuit boards (PCBs).
• Enhanced Contrast: The black housing material significantly improves the contrast ratio, making the illuminated LEDs more visible against the board.
• Energy Efficiency: The device features low power consumption while maintaining high luminous efficiency.
• Environmental Compliance: This is a lead-free product compliant with the RoHS (Restriction of Hazardous Substances) directive.
• Chip Technology: Utilizes AlInGaP semiconductor technology for the yellow-green (569nm) and yellow (589nm) emission chips.

1.2 Target Applications

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

• Computer systems and peripherals
• Communication devices
• Consumer electronics
• Industrial control and instrumentation

2. Technical Parameters: In-Depth Objective Interpretation

2.1 Absolute Maximum Ratings

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

• Power Dissipation (Pd): 52 mW per LED. This is the maximum power the LED chip can safely dissipate as heat.
• Peak Forward Current (I_FP): 60 mA. This current can only be applied under pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 10μs).
• DC Forward Current (I_F): 20 mA. This is the maximum continuous forward current recommended for reliable long-term operation.
• Operating Temperature (T_opr): -40°C to +85°C. The ambient temperature range within which the device will function.
• Storage Temperature (T_stg): -45°C to +100°C. The temperature range for non-operational storage.
• Lead Soldering Temperature: 260°C for a maximum of 5 seconds, measured 2.0mm from the LED body. This is critical for wave or hand soldering processes.

2.2 Electrical and Optical Characteristics

These are the typical performance parameters measured at an ambient temperature (T_A) of 25°C and a forward current (I_F) of 10mA, unless otherwise specified.

• Luminous Intensity (I_V):
  • LED1 (Yellow-Green): Typical 15 mcd, ranging from 8.7 mcd (Min) to 29 mcd (Max).
  • LED2 & 3 (Yellow): Typical 14 mcd, ranging from 3.8 mcd (Min) to 30 mcd (Max). A ±15% testing tolerance is applied to these guarantees.
• Viewing Angle (2θ_1/2): 100 degrees for all LEDs. This is the full angle at which luminous intensity drops to half its peak value.
• Peak Wavelength (λ_P):
  • LED1 (Yellow-Green): 572 nm.
  • LED2 & 3 (Yellow): 591 nm.
• Dominant Wavelength (λ_d): Derived from CIE coordinates, this defines the perceived color.
  • LED1 (Yellow-Green): 570 nm (566-573 nm range).
  • LED2 & 3 (Yellow): 588 nm (584-593 nm range). Testing tolerance is ±1nm.
• Spectral Half-Width (Δλ): 15 nm for all LEDs, indicating the spectral purity.
• Forward Voltage (V_F): Typical 2.0V, with a maximum of 2.6V for all LEDs at 10mA.
• Reverse Current (I_R): Maximum 10 μA at a reverse voltage (V_R) of 5V. Important: The device is not designed for operation in reverse bias; this test condition is for characterization only.

3. Binning System Explanation

The datasheet indicates inherent variations in key parameters. While a formal binning table is not provided, the Min/Typ/Max values for luminous intensity and dominant wavelength imply a sorting or selection process to ensure devices meet the specified ranges. Designers should account for these variations, especially for intensity matching in multi-LED applications.

4. Performance Curve Analysis

The datasheet references typical characteristic curves which are essential for design.

• I-V Curve: Shows the relationship between forward voltage (V_F) and forward current (I_F). This is non-linear and crucial for selecting the appropriate current-limiting resistor.
• Relative Luminous Intensity vs. Forward Current: Demonstrates how light output increases with current, typically in a near-linear relationship within the operating range.
• Relative Luminous Intensity vs. Ambient Temperature: Shows the derating of light output as junction temperature increases. Performance decreases at higher temperatures.
• Spectral Distribution: Illustrates the relative power emitted across wavelengths, centered around the peak and dominant wavelengths.

5. Mechanical and Package Information

5.1 Outline Dimensions

The device uses a through-hole right-angle package. Key dimensional notes:

• All dimensions are in millimeters (inches provided in tolerance).
• Standard tolerance is ±0.25mm (±0.010") unless otherwise specified on the drawing.
• The housing material is black or dark gray plastic, rated UL 94V-0 for flammability.
• LED1 has a yellow-green chip with a green diffused lens. LED2 and LED3 have yellow chips with yellow diffused lenses.

5.2 Polarity Identification

For through-hole LEDs, the cathode is typically identified by a flat side on the lens, a shorter lead, or a marking on the housing. The specific identification method should be verified from the detailed dimensional drawing referenced in the datasheet.

6. Soldering and Assembly Guidelines

6.1 Storage

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

6.2 Cleaning

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

6.3 Lead Forming

Bend leads at a point at least 3mm from the base of the LED lens. Do not use the lens base as a fulcrum. Perform forming before soldering and at room temperature. Use minimal force during PCB insertion to avoid mechanical stress.

6.4 Soldering Parameters

Maintain a minimum 2mm clearance from the lens/holder base to the solder point. Do not immerse the lens in solder.

• Hand Soldering (Iron): Max temperature 350°C, max time 3 seconds per lead.
• Wave Soldering: Pre-heat to max 120°C for up to 100s. Solder wave at max 260°C for max 5 seconds.
• Reflow Soldering (Profile for Reference):
  • Preheat/Soak: 150-200°C for up to 100s.
  • Time Above Liquidous (T_L=217°C): 60-90s.
  • Peak Temperature (T_P): 250°C (Classification Temp T_C=245°C for max 30s).
  • Total time from 25°C to peak: 5 minutes max.

Warning: Excessive temperature or time can deform the lens or cause catastrophic LED failure.

7. Application Recommendations

7.1 Drive Circuit Design

LEDs are current-driven devices. To ensure uniform brightness when connecting multiple LEDs in parallel, it is strongly recommended to use a individual current-limiting resistor in series with each LED (Circuit A). Connecting LEDs directly in parallel without individual resistors (Circuit B) is not recommended, as small variations in forward voltage (V_F) between LEDs will cause significant differences in current share and, consequently, brightness.

7.2 Electrostatic Discharge (ESD)

Although not fully detailed in the excerpt, LEDs are generally sensitive to ESD. Proper ESD handling procedures (use of grounded wrist straps, anti-static mats, etc.) should be followed during assembly and handling to prevent latent or immediate damage.

7.3 Thermal Management

While the power is low, operating at or near the maximum current (20mA) and/or at high ambient temperatures (towards +85°C) will reduce light output and potentially affect longevity. Ensure adequate airflow if used in high-density or high-temperature environments.

8. Technical Comparison and Differentiation

The LTL-R42FGYYHKP differentiates itself through its integrated multi-LED, right-angle housing design. This provides a ready-made indicator solution that combines multiple colors (yellow-green and yellow) in a single, easy-to-mount package, saving board space and assembly time compared to using discrete LEDs and separate holders. The use of AlInGaP technology offers good efficiency and color stability for the yellow spectrum.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED at 20mA continuously?
A: Yes, 20mA is the maximum recommended DC forward current. For longest lifetime and reliability, operating at a lower current (e.g., 10-15mA) is often advisable.

Q: Why is there such a wide range in luminous intensity (e.g., 3.8 to 30 mcd)?
A: This reflects natural variations in semiconductor manufacturing. The device is guaranteed to fall within this range. For applications requiring tight brightness matching, LEDs can be selected (binned) from within a narrower range.

Q: Can I use a single resistor for two LEDs in parallel?
A: It is not recommended (see Circuit B warning). Due to V_F variance, one LED may draw most of the current, leading to uneven brightness and potential overstress of the brighter LED. Always use individual resistors.

Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λ_P) is the wavelength at the highest point of the emission spectrum. Dominant wavelength (λ_d) is calculated from color coordinates and represents the single wavelength of the pure spectral color that would match the perceived color of the LED. λ_d is more relevant for color specification.

10. Practical Design and Usage Case

Scenario: Designing a status panel for an industrial controller requiring distinct indicators for "Power On" (steady yellow-green) and "Fault" (blinking yellow).

Implementation: A single LTL-R42FGYYHKP component can be used. LED1 (yellow-green) is connected via a current-limiting resistor to a constant voltage source (e.g., 5V) to indicate "Power On." LED2 or LED3 (yellow) is connected via its own resistor to a microcontroller GPIO pin configured for blinking output to indicate "Fault." The right-angle housing allows the panel to be mounted perpendicular to the main PCB, directing light optimally towards the user. The black housing ensures high contrast against the panel bezel.

11. Operating 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 and holes recombine in the active region (made of AlInGaP in this case). This recombination releases energy in the form of photons (light). The specific wavelength (color) of the light is determined by the bandgap energy of the semiconductor material. A diffused lens over the chip helps to scatter the light, creating the wide 100-degree viewing angle.

12. Technology Trends

Through-hole indicator LEDs like the LTL-R42FGYYHKP continue to serve applications requiring robustness, ease of manual assembly, or high reliability in harsh environments. However, the broader industry trend is towards surface-mount device (SMD) LEDs for most new designs due to their smaller size, suitability for automated pick-and-place assembly, and lower profile. Advancements in LED technology focus on increasing efficiency (lumens per watt), improving color rendering, and enhancing reliability under higher temperature and current conditions. The fundamental operating principle remains unchanged, but materials and packaging techniques continue to evolve.