LTL-R42FTGYH106PT Bicolor LED Lamp Datasheet - Green/Yellow - 525nm/587nm - 20mA/30mA - Through-Hole Package

1. Product Overview

The LTL-R42FTGYH106PT is a bicolor through-hole LED lamp designed for use as a Circuit Board Indicator (CBI). It integrates a black plastic right-angle holder (housing) that mates with two distinct LED chips: one emitting green light and the other emitting yellow light. This component is engineered for straightforward assembly onto printed circuit boards (PCBs) and is supplied in tape and reel packaging for automated placement.

1.1 Core Advantages

• Ease of Assembly: The design is optimized for simplified circuit board assembly processes.
• Enhanced Contrast: The black housing material provides a high contrast ratio, improving indicator visibility.
• High Efficiency: Offers low power consumption with high luminous output.
• Environmental Compliance: This is a lead-free product compliant with RoHS directives.
• Dual Color Source: Incorporates an InGaN chip for green emission (525nm) and an AlInGaP chip for yellow emission (587nm).
• Automation Ready: Packaged on tape and reel for compatibility with high-volume, automated pick-and-place equipment.

1.2 Target Applications

This LED lamp is suitable for a variety of electronic equipment requiring status or indicator functions. Primary application areas include:

• Communication equipment
• Computer and peripheral devices
• Consumer electronics
• Industrial control systems and instrumentation

2. In-Depth Technical Parameter Analysis

All specifications are defined at an ambient temperature (TA) of 25°C unless otherwise stated. Understanding these parameters is critical for reliable circuit design.

2.1 Absolute Maximum Ratings

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

2.2 Electrical & Optical Characteristics

These are the typical operating parameters under specified test conditions.

Key Notes:

• Luminous intensity is measured per the CIE photopic eye-response curve.
• The viewing angle (θ1/2) is the off-axis angle where intensity drops to half its axial value.
• Dominant wavelength defines the perceived color on the CIE chromaticity diagram.
• The device is not designed for reverse bias operation; the reverse current test is for characterization only.

2.3 Thermal Characteristics

The specified operating and storage temperature ranges ensure long-term reliability. The power dissipation ratings (70mW for Green, 78mW for Yellow) must be considered in conjunction with ambient temperature to prevent junction temperature from exceeding safe limits, which can degrade light output and lifespan.

3. Binning System Explanation

To ensure color and brightness consistency in production, LEDs are sorted into bins based on key parameters. The LTL-R42FTGYH106PT uses separate binning for luminous intensity and dominant wavelength.

3.1 Green LED Binning

Luminous Intensity @ 10mA:

• Bin HJ: 180 mcd (Min) to 310 mcd (Max)
• Bin KL: 310 mcd (Min) to 520 mcd (Max)
• Bin MN: 520 mcd (Min) to 880 mcd (Max)
• Tolerance on each bin limit is ±15%.

Dominant Wavelength @ 10mA:

• Bin G09: 516.0 nm to 520.0 nm
• Bin G10: 520.0 nm to 527.0 nm
• Bin G11: 527.0 nm to 535.0 nm
• Tolerance on each bin limit is ±1 nm.

3.2 Yellow LED Binning

Luminous Intensity @ 20mA:

• Bin HJ: 180 mcd (Min) to 310 mcd (Max)
• Bin KL: 310 mcd (Min) to 520 mcd (Max)
• Bin MN: 520 mcd (Min) to 880 mcd (Max)
• Tolerance on each bin limit is ±15%.

Dominant Wavelength @ 20mA:

• Bin H15: 584.0 nm to 586.0 nm
• Bin H16: 586.0 nm to 588.0 nm
• Bin H17: 588.0 nm to 590.0 nm
• Bin H18: 590.0 nm to 592.0 nm
• Bin H19: 592.0 nm to 594.0 nm
• Tolerance on each bin limit is ±1 nm.

4. Performance Curve Analysis

The datasheet references typical performance curves which illustrate the relationship between key parameters. While the specific graphs are not reproduced here, their implications are critical for design.

4.1 Forward Current vs. Luminous Intensity (I-V Curve)

This curve shows that luminous intensity is approximately proportional to forward current within the recommended operating range. Driving the LED above its rated current leads to super-linear increase in light output but also significantly increases junction temperature and accelerates degradation.

4.2 Temperature Dependence

LED light output typically decreases as junction temperature rises. The green InGaN and yellow AlInGaP chips will have different temperature coefficients. Designers must account for this derating in applications with high ambient temperatures or poor thermal management to ensure consistent brightness.

4.3 Spectral Distribution

The spectral curves for each color show the concentration of emitted light around the peak wavelength (526nm for green, 588nm for yellow). The narrower half-width for yellow (15nm typical) indicates a more spectrally pure color compared to green (35nm typical).

5. Mechanical & Packaging Information

5.1 Outline Dimensions

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

• All dimensions are in millimeters (with inch equivalents).
• Standard tolerance is ±0.25mm (±0.010") unless specified otherwise.
• The housing material is black or dark gray plastic.
• LED1 is green with a green diffused lens; LED2 is yellow with a yellow diffused lens.

5.2 Polarity Identification

Correct polarity is essential for operation. The datasheet drawing indicates the anode and cathode leads for each LED within the common housing. Designers must reference the physical drawing to identify the pinout correctly for PCB layout.

5.3 Packaging Specification

The device is supplied in an industry-standard tape and reel format for automated assembly.

• Carrier Tape: Black conductive polystyrene alloy, 0.50mm ±0.06mm thick.
• Reel: Standard 13-inch (330mm) diameter reel.
• Quantity per Reel: 350 pieces.
• Master Packing: Reels are packed in Moisture Barrier Bags (MBB) with desiccant. Cartons contain multiple reels, with a standard outer carton holding 7,000 pieces total.

6. Soldering & Assembly Guidelines

Adherence to these guidelines is mandatory to prevent mechanical or thermal damage.

6.1 Storage Conditions

For long-term storage, maintain an environment not exceeding 30°C and 70% relative humidity. Components removed from their original sealed, moisture-barrier packaging should be used within three months. For extended storage outside the original package, use a sealed container with desiccant or a nitrogen ambient.

6.2 Cleaning

If cleaning is necessary after soldering, use only alcohol-based solvents such as isopropyl alcohol. Avoid aggressive or unknown chemical cleaners.

6.3 Lead Forming

• Bend leads at a point at least 3mm from the base of the LED lens/holder.
• Do not use the base of the lead frame as a fulcrum.
• Perform all lead forming at room temperature and before the soldering process.
• During PCB insertion, apply the minimum clinch force required to avoid stressing the component.

6.4 Soldering Process

A minimum clearance of 2mm must be maintained between the solder point and the base of the lens/holder. Never immerse the lens into solder.

Recommended Soldering Conditions:

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

7. Application & Design Considerations

7.1 Drive Circuit Design

LEDs are current-driven devices. To ensure uniform brightness when driving multiple LEDs in parallel, it is essential to use a individual current-limiting resistor in series with each LED. Driving LEDs directly from a voltage source without current regulation leads to uneven brightness and potential overcurrent damage due to the natural variation in forward voltage (Vf) from device to device.

7.2 Thermal Management

While the through-hole design offers some heat sinking via the leads, applications operating at high ambient temperatures or at the maximum forward current should consider the PCB layout. Providing adequate copper area around the lead insertion points on the PCB can help dissipate heat and maintain stable performance.

7.3 Optical Considerations

The different viewing angles (100° for green, 65° for yellow) mean the yellow LED will have a more focused beam. This should be considered if the indicator needs to be visible from wide angles. The black housing improves contrast by absorbing stray light, making the illuminated LED easier to see.

8. Technical Comparison & Differentiation

The LTL-R42FTGYH106PT offers specific advantages in its category:

• Dual Color in Single Package: Saves board space and simplifies assembly compared to using two separate single-color LEDs.
• Right-Angle Design: Allows the light to be emitted parallel to the PCB surface, ideal for edge-lit panels or status indicators on vertical boards.
• Pre-Assembled Holder: The integrated black holder eliminates the need for a separate light pipe or spacer, reducing part count and assembly steps.
• Material Choice: The black housing is superior for contrast compared to clear or translucent housings commonly found in similar indicators.

9. Frequently Asked Questions (FAQ)

9.1 Can I drive both LEDs simultaneously?

Yes, but they must be driven independently with separate current-limiting resistors, as they have different forward voltage (Vf) and recommended operating current (10mA for green, 20mA for yellow) characteristics.

9.2 What is the difference between peak wavelength and dominant wavelength?

Peak wavelength (λP) is the wavelength at which the spectral power distribution is maximum. Dominant wavelength (λd) is the single wavelength perceived by the human eye, calculated from the CIE chromaticity coordinates. λd is more relevant for color specification.

9.3 How do I select the correct current-limiting resistor?

Use Ohm's Law: R = (V_supply - Vf_LED) / I_LED. For the green LED at 10mA with a typical Vf of 2.9V and a 5V supply: R = (5 - 2.9) / 0.01 = 210 Ω. Always calculate for the worst-case (minimum Vf) to ensure current does not exceed the maximum rating.

9.4 Is this LED suitable for outdoor use?

The datasheet states it is good for indoor and outdoor signs. However, for harsh outdoor environments with prolonged UV exposure, wide temperature swings, and moisture, the specific lens material's weatherability and the integrity of the housing seal should be verified for the intended lifetime.

10. Design-in Case Study

Scenario: Designing a status panel for an industrial router with Power, Network Activity, and System Error indicators. Space is limited.

Implementation: A single LTL-R42FTGYH106PT can serve a dual-purpose indicator slot. The green LED can indicate "Power On / Normal Operation." The yellow LED can be programmed to indicate "Network Activity" (blinking) or "System Warning" (steady). This consolidates two indicator functions into one footprint, simplifying the front panel design and PCB layout. The right-angle emission is perfect for a panel where the PCB is mounted perpendicular to the viewing surface.

11. 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 wavelength (color) of the emitted light is determined by the energy bandgap of the semiconductor material. The green LED uses an Indium Gallium Nitride (InGaN) chip, while the yellow LED uses an Aluminium Indium Gallium Phosphide (AlInGaP) chip, each chosen for their specific bandgap energies corresponding to their respective colors.

12. Technology Trends

While through-hole LEDs remain vital for prototyping, serviceable equipment, and certain industrial applications, the broader industry trend is towards surface-mount device (SMD) packages like 0603, 0402, and even smaller for higher density. SMDs enable fully automated assembly, smaller form factors, and better thermal performance to the PCB. However, through-hole components like the LTL-R42FTGYH106PT offer superior mechanical strength, easier manual handling for low-volume production, and often higher single-point brightness, ensuring their continued relevance in specific market segments.