LTL-R42FTG2H106PT LED Lamp Datasheet - Right-Angle Holder - Green 525nm - 2.9V 10mA - English Technical Document

1. Product Overview

This document details the specifications for a through-hole mounted LED indicator lamp. The device consists of a green LED housed within a black plastic right-angle holder, designed for direct mounting onto printed circuit boards (PCBs). The primary function is to serve as a status or power indicator in electronic equipment.

1.1 Core Advantages

• Enhanced Contrast: The black housing provides a high contrast background, improving the visibility of the illuminated green diffused lens.
• Energy Efficiency: Features low power consumption and high luminous efficiency.
• Environmental Compliance: This is a lead-free product compliant with RoHS directives.
• Ease of Assembly: The right-angle, stackable housing design facilitates straightforward manual or automated assembly processes.
• Standard Packaging: Supplied in tape and reel format suitable for automated placement equipment.

1.2 Target Applications

This component is suitable for a wide range of electronic devices, including but not limited to:

• Computer peripherals and motherboards
• Communication equipment (routers, switches, modems)
• Consumer electronics (audio/video equipment, appliances)
• Industrial control systems and instrumentation

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

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

• Power Dissipation (Pd): 70 mW maximum. Exceeding this can lead to overheating and reduced lifespan.
• Peak Forward Current (I_FP): 60 mA, permissible only under pulsed conditions (duty cycle ≤ 10%, pulse width ≤ 10µs).
• DC Forward Current (I_F): 20 mA continuous. This is the recommended maximum for reliable long-term operation.
• Operating Temperature (T_opr): -30°C to +85°C. Performance is characterized at 25°C; operation at temperature extremes may affect light output and forward voltage.
• Soldering Temperature: Leads can withstand 260°C for a maximum of 5 seconds, provided the soldering point is at least 2.0mm from the LED body.

2.2 Electro-Optical Characteristics

Measured at an ambient temperature (T_A) of 25°C with a forward current (I_F) of 10mA, unless otherwise stated.

• Luminous Intensity (I_V): Ranges from a minimum of 180 mcd to a typical 420 mcd, with a maximum of 880 mcd. The actual value is binned (see Section 3). Measurement follows the CIE photopic eye-response curve.
• Viewing Angle (2θ_1/2): 100 degrees. This is the full angle at which luminous intensity drops to half its on-axis value, characteristic of a diffused lens providing wide-angle visibility.
• Peak Wavelength (λ_P): 526 nm. This is the wavelength at the highest point of the emission spectrum.
• Dominant Wavelength (λ_d): 525 nm (typical). This is the single wavelength perceived by the human eye, derived from the CIE chromaticity diagram, and defines the green color. It is binned from 516nm to 535nm.
• Spectral Bandwidth (Δλ): 35 nm. This indicates the spectral purity; a narrower bandwidth would indicate a more monochromatic green.
• Forward Voltage (V_F): 2.9V typical, ranging from 2.4V to 3.5V at 10mA. This parameter must be considered when designing current-limiting circuitry.
• Reverse Current (I_R): 10 µA maximum at a reverse voltage (V_R) of 5V. Important: 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. This allows designers to select parts meeting specific application requirements.

3.1 Luminous Intensity Binning

Bins are defined for luminous intensity measured at I_F=10mA. Each bin limit has a ±15% testing tolerance.

• HJ Bin: 180 mcd (Min) to 310 mcd (Max)
• KL Bin: 310 mcd (Min) to 520 mcd (Max)
• MN Bin: 520 mcd (Min) to 880 mcd (Max)

3.2 Dominant Wavelength (Hue) Binning

Bins are defined for the dominant wavelength, which determines the precise shade of green. Each bin limit has a ±1nm tolerance.

• G09 Bin: 516.0 nm to 520.0 nm (Greener, shorter wavelength)
• G10 Bin: 520.0 nm to 527.0 nm (Central green)
• G11 Bin: 527.0 nm to 535.0 nm (Yellowish-green, longer wavelength)

4. Performance Curve Analysis

Typical performance curves (referenced in the datasheet) provide insight into device behavior under varying conditions. While specific graphs are not reproduced here, their implications are analyzed.

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

The I-V curve is non-linear. The forward voltage (V_F) increases with current but has a positive temperature coefficient—it decreases as the junction temperature rises for a given current. This must be accounted for in constant-current driver designs.

4.2 Luminous Intensity vs. Forward Current

Light output is approximately proportional to forward current within the recommended operating range. However, efficiency may drop at very high currents due to increased thermal effects. Operating near the maximum DC current (20mA) will provide maximum brightness but may impact long-term reliability compared to a lower drive current.

4.3 Temperature Dependence

Luminous intensity typically decreases as the junction temperature increases. The device's ability to dissipate heat through its leads and the PCB will affect its sustained brightness in an application. The wide operating temperature range (-30°C to +85°C) indicates robust performance across environments, though light output at extremes will differ from the 25°C specification.

5. Mechanical and Packaging Information

5.1 Outline Dimensions and Mounting

The component features a right-angle design, allowing it to be mounted on the edge of a PCB with the lens facing perpendicular to the board surface. Critical dimensional notes include:

• All dimensions are in millimeters.
• Standard tolerance is ±0.25mm unless otherwise specified on the drawing.
• The housing material is black/dark gray plastic.
• The leads must be formed, if necessary, at a point no closer than 2mm from the base of the lens/housing to avoid stress damage.

5.2 Polarity Identification

Polarity is indicated by the physical structure of the housing or the lead length (typically, the longer lead is the anode). The datasheet drawing should be consulted for the exact identification method for this specific part number to ensure correct orientation during assembly.

5.3 Tape and Reel Packaging

The component is supplied on embossed carrier tape wound onto a 13-inch reel.

• Carrier Tape: Made of black conductive polystyrene alloy, 0.50mm thick (±0.06mm).
• Reel Capacity: 350 pieces per reel.
• Pitch Tolerance: Cumulative tolerance for 10 sprocket holes is ±0.20mm, ensuring compatibility with automated pick-and-place machines.

5.4 Carton Packaging

For bulk shipment and moisture protection:

• 2 reels (700 pieces total) are packed with a humidity indicator card and desiccants into one Moisture Barrier Bag (MBB).
• 1 MBB is packed into an Inner Carton.
• 10 Inner Cartons (7,000 pieces total) are packed into an Outer Carton.

6. Soldering and Assembly Guidelines

6.1 Storage Conditions

• Sealed Package: Store at ≤30°C and ≤70% RH. Use within one year of package seal date.
• Opened Package: If the MBB is opened, components should be stored at ≤30°C and ≤60% RH. It is strongly recommended to complete IR reflow soldering within 168 hours (7 days) of opening.
• Extended Storage (Opened): For storage beyond 168 hours, bake at 60°C for at least 48 hours before SMT assembly to remove absorbed moisture and prevent "popcorning" damage during reflow.

6.2 Cleaning

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

6.3 Lead Forming and PCB Mounting

• Perform any lead bending before soldering, at room temperature.
• Bend leads at a point ≥2mm from the base of the lens/holder. Do not use the holder body as a fulcrum.
• During PCB insertion, apply the minimum clinch force necessary to avoid imposing excessive mechanical stress on the LED package.

6.4 Soldering Process Parameters

Maintain a minimum distance of 2mm between the solder point and the base of the lens/holder.

• Hand Soldering (Iron):
  • Temperature: ≤ 350°C
  • Time: ≤ 3 seconds per joint
• Wave Soldering:
  • Pre-heat Temperature: ≤ 120°C
  • Pre-heat Time: ≤ 100 seconds
  • Solder Wave Temperature: ≤ 260°C
  • Contact Time: ≤ 5 seconds
  • Dipping Position: ≥2mm from lens base
• Reflow Soldering (SMT process for the holder itself if applicable):
  • Preheat/Soak: 150°C to 200°C over ≤100s
  • Time Above Liquidous (T_L=217°C): 60-150s
  • Peak Temperature (T_P): 250°C max
  • Specified Classification Temperature (T_C): 245°C

7. Application Notes and Design Considerations

7.1 Typical Application Circuits

This LED is typically driven by a constant current source or, more commonly, a voltage source with a series current-limiting resistor. The resistor value (R_s) can be calculated using Ohm's Law: R_s = (V_supply - V_F) / I_F. Use the maximum V_F from the datasheet (3.5V) to ensure the minimum required current is met under all conditions. For example, with a 5V supply and a target I_F of 10mA: R_s = (5V - 3.5V) / 0.01A = 150 Ω. A standard 150Ω or 160Ω resistor would be suitable.

7.2 Thermal Management

While the power dissipation is low (70mW max), proper thermal design extends lifespan and maintains brightness. Ensure the PCB has adequate copper area connected to the LED's leads to act as a heat sink, especially if operating near maximum current or in high ambient temperatures.

7.3 Optical Design

The built-in diffused lens provides a wide, even viewing angle. For applications requiring light piping or additional diffusion, the initial wide angle makes this LED a good candidate. The black housing minimizes internal reflections and light leakage, improving contrast.

8. Frequently Asked Questions (FAQs)

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

Peak Wavelength (λ_P) is the physical wavelength at which the LED emits the most optical power. Dominant Wavelength (λ_d) is a calculated value based on human color perception (CIE chart) that best represents the color we see. For a monochromatic green LED, they are often close, but λ_d is the critical parameter for color matching in an application.

8.2 Can I drive this LED with a 3.3V supply without a resistor?

Not recommended. The forward voltage ranges from 2.4V to 3.5V. At 3.3V, an LED with a low V_F (e.g., 2.5V) would experience a large, uncontrolled current, potentially exceeding its maximum rating and causing immediate or gradual failure. Always use a current-limiting mechanism.

8.3 Why is the 168-hour floor life important after opening the MBB?

Plastic LED packages can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can vaporize rapidly, creating internal pressure that can delaminate the package or crack the epoxy lens ("popcorning"). The 168-hour limit and baking procedure are critical to prevent this manufacturing defect.

9. Practical Use Case Example

Scenario: Designing a power indicator for a network switch.

• Requirement: A clear, wide-angle green light visible from the front panel.
• Component Selection: The LTL-R42FTG2H106PT is chosen for its right-angle mounting (suitable for vertical PCBs behind a panel), wide 100° viewing angle, and appropriate brightness.
• Circuit Design: The switch's internal logic supply is 3.3V. Using the formula with max V_F=3.5V and target I_F=8mA (for long life and sufficient brightness): R_s = (3.3V - 3.5V) / 0.008A. This yields a negative value, indicating 3.3V may be insufficient to reliably drive all units. Therefore, the 5V supply rail is used instead: R_s = (5V - 3.5V) / 0.008A = 187.5 Ω. A 180Ω or 200Ω resistor is selected.
• Layout: The LED is placed on the PCB edge. The two leads are connected to small copper pours to aid heat dissipation. The assembly instructions for lead bending and soldering clearance are followed precisely.
• Result: A reliable, consistently bright power indicator that meets all design and manufacturing requirements.

10. Operating Principle

This device is a light-emitting diode (LED). It operates on the principle of electroluminescence in a semiconductor material (InGaN for green light). 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 Indium Gallium Nitride (InGaN) semiconductor determines the wavelength of the emitted light, in this case, centered in the green spectrum (~525nm). The integrated diffused lens scatters the light, creating a uniform, wide beam pattern.

11. Technology Trends

Through-hole LEDs with discrete holders remain relevant for applications requiring high reliability, ease of manual assembly, repair, or where wave soldering is the primary process. The industry trend for status indicators, however, continues to shift towards surface-mount device (SMD) LEDs due to their smaller footprint, suitability for fully automated assembly, and lower profile. The right-angle through-hole design offers a specific mechanical advantage for panel mounting that some SMD solutions replicate with side-view packages. Advances in LED technology focus on increasing efficiency (more light per watt), improving color consistency, and enhancing reliability under higher temperature and humidity conditions.