LTL-R42FEWADHBPT Through Hole LED Lamp Datasheet - Red 625nm - 2.5V - 52mW - English Technical Document

1. Product Overview

The LTL-R42FEWADHBPT is a Circuit Board Indicator (CBI) component, consisting of a black plastic right-angle holder (housing) mated with a specific LED lamp. This design is intended for straightforward assembly onto printed circuit boards (PCBs). The product is part of a family available in various configurations, including top-view and right-angle orientations, as well as horizontal or vertical arrays that are stackable for design flexibility.

1.1 Core Advantages

• Ease of Assembly: The through-hole design and holder facilitate simple and reliable circuit board mounting.
• Energy Efficiency: Features low power consumption and high luminous efficiency.
• Environmental Compliance: This is a lead-free product compliant with RoHS directives.
• Standardized Packaging: Supplied in tape and reel format compatible with automated assembly processes.

1.2 Target Applications

This indicator lamp is suitable for a broad range of electronic equipment, including:

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

2. In-Depth Technical Parameter Analysis

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 maximum.
• Peak Forward Current (I_FP): 60 mA, permissible only under pulsed conditions (duty cycle ≤ 1/10, pulse width ≤ 10μs).
• Continuous Forward Current (I_F): 20 mA DC maximum.
• Current Derating: Required above 30°C ambient temperature at a rate of 0.27 mA/°C.
• Operating Temperature Range (T_opr): -30°C to +85°C.
• Storage Temperature Range (T_stg): -40°C to +100°C.

2.2 Electro-Optical Characteristics

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): Ranges from a minimum of 3.8 mcd to a maximum of 50 mcd, with a typical value of 18 mcd. A ±15% testing tolerance is applied to bin limits.
• Viewing Angle (2θ_1/2): Approximately 100 degrees, defined as the off-axis angle where intensity drops to half its axial value.
• Peak Wavelength (λ_P): 630 nm.
• Dominant Wavelength (λ_d): Ranges from 613.5 nm to 633 nm, defining the perceived color (red).
• Spectral Bandwidth (Δλ): 20 nm, typical.
• Forward Voltage (V_F): Typically 2.5V, with a maximum of 2.5V at 10mA.
• Reverse Current (I_R): 10 μA maximum at a reverse voltage (V_R) of 5V. The device is not designed for operation in reverse bias.

3. Binning System Specification

The product is classified into bins based on key optical parameters to ensure color and brightness consistency within an application.

3.1 Luminous Intensity Binning

Binned at I_F = 10mA. Each bin code has a ±15% tolerance on its limits.

• 3ST: 3.8 – 6.5 mcd
• 3UV: 6.5 – 11 mcd
• 3WX: 11 – 18 mcd
• 3YZ: 18 – 30 mcd
• AB: 30 – 50 mcd

3.2 Dominant Wavelength (Hue) Binning

Binned at I_F = 10mA. Tolerance for each bin limit is ±1 nm.

• H27: 613.5 – 617.0 nm
• H28: 617.0 – 621.0 nm
• H29: 621.0 – 625.0 nm
• H30: 625.0 – 629.0 nm
• H31: 629.0 – 633.0 nm

4. Performance Curve Analysis

The datasheet includes typical characteristic curves which are essential for circuit design and understanding device behavior under varying conditions.

• Relative Luminous Intensity vs. Forward Current: Shows the non-linear relationship between drive current and light output.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the decrease in light output as junction temperature rises, crucial for thermal management.
• Forward Voltage vs. Forward Current: Illustrates the diode's I-V characteristic, important for selecting current-limiting resistors.
• Spectral Distribution: Depicts the relative radiant power across wavelengths, centered around 630 nm for this red LED.
• Viewing Angle Pattern: A polar diagram showing the spatial distribution of luminous intensity.

5. Mechanical and Packaging Information

5.1 Outline Dimensions

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

• All dimensions are in millimeters (with inch equivalents).
• Standard tolerance is ±0.25mm (±0.010") unless specified otherwise.
• The holder (housing) is made of black or dark gray plastic.
• The integrated LED lamp is red with a red diffused lens.

5.2 Packaging Specification

• Carrier Tape: Black conductive polystyrene alloy. 10-sprocket hole pitch cumulative tolerance is ±0.20.
• Reel: Standard 13-inch reel containing 400 pieces.
• Carton:
  • 1 reel is packed with a desiccant and humidity indicator card in a Moisture Barrier Bag (MBB).
  • 2 MBBs are packed in 1 Inner Carton (total 800 pcs).
  • 10 Inner Cartons are packed in 1 Outer Carton (total 8,000 pcs).

6. Soldering and Assembly Guidelines

6.1 Storage Conditions

• Sealed Package: Store at ≤30°C and ≤70% RH. Use within one year.
• Opened Package: Store at ≤30°C and ≤60% RH. Components should be IR-reflowed within 168 hours (1 week) of opening. For storage beyond 168 hours, a 48-hour bake at 60°C is recommended before SMT assembly.

6.2 Lead Forming

Bending must be performed at a point at least 2.0 mm from the base of the LED lens/holder, at normal temperature, and before soldering. The base of the lead frame should not be used as a fulcrum.

6.3 Soldering Parameters

A minimum clearance of 2.0 mm must be maintained between the solder point and the base of the lens/holder.

• Hand Soldering (Iron): Maximum temperature 350°C for a maximum of 3 seconds (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 a maximum of 5 seconds.

6.4 Cleaning

If necessary, clean only with alcohol-based solvents such as isopropyl alcohol.

7. Application Notes and Design Considerations

7.1 Typical Application Scenarios

This LED is suitable for general-purpose status indication in both indoor and outdoor signage, as well as standard electronic equipment across computing, communications, consumer, and industrial sectors.

7.2 Design Considerations

• Current Limiting: Always use a series resistor to limit the forward current to 20 mA DC or less. The resistor value can be calculated using the typical forward voltage (V_F = 2.5V).
• Thermal Management: Observe the current derating curve above 30°C ambient. In high-temperature environments or enclosed spaces, reduce the drive current to prevent exceeding the maximum junction temperature.
• Mechanical Stress: Apply minimal clinch force during PCB assembly to avoid stressing the LED package. Avoid any external stress on the leads during soldering while the device is hot.
• Reverse Voltage Protection: As the device has a low reverse breakdown voltage, ensure circuit design prevents the application of reverse bias exceeding 5V.

8. Frequently Asked Questions (FAQs)

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

Peak Wavelength (λ_P): The wavelength at which the emitted optical power is maximum (630 nm for this device). Dominant Wavelength (λ_d): A single wavelength derived from the CIE chromaticity diagram that best represents the perceived color of the light (ranging from 613.5 to 633 nm). Dominant wavelength is more relevant for color specification.

8.2 Can I drive this LED with a 5V supply?

Yes, but a current-limiting resistor is mandatory. For example, to achieve a typical I_F of 10mA from a 5V supply: R = (V_supply - V_F) / I_F = (5V - 2.5V) / 0.01A = 250 Ω. A standard 240 Ω or 270 Ω resistor would be appropriate.

8.3 Why is the storage and handling after opening the package so critical?

LED packages can absorb moisture from the atmosphere. During the high-temperature reflow soldering process, this trapped moisture can rapidly expand, causing internal delamination or cracking ("popcorning"), which leads to failure. The specified bake-out process removes this absorbed moisture.

8.4 How do I interpret the bin codes on the packaging?

The bin code (e.g., 3WX-H29) specifies the luminous intensity range (3WX = 11-18 mcd) and the dominant wavelength range (H29 = 621.0-625.0 nm). For applications requiring uniform appearance, specifying and using components from the same bin is essential.

9. Practical Design Example

Scenario: Designing a power-on indicator for a device powered by a 3.3V rail, requiring a medium-brightness red signal.

1. Component Selection: Choose a bin code like 3WX-H30 for consistent brightness (11-18 mcd) and color (625-629 nm red).
2. Circuit Design: Target I_F = 10mA for long life and adequate brightness.
   • Calculate resistor: R = (3.3V - 2.5V) / 0.01A = 80 Ω.
   • Use the nearest standard value, e.g., 82 Ω.
   • Verify power in resistor: P = I²R = (0.01)² * 82 = 0.0082W. A standard 1/8W or 1/10W resistor is sufficient.
3. PCB Layout: Place the LED footprint according to the right-angle dimension drawing. Ensure the 2.0mm keep-out zone from the lens base is respected in the solder mask and copper pour.
4. Assembly: Follow the wave soldering profile specified, ensuring the PCB is pre-heated and the LED is not immersed beyond the allowed depth.

10. Operational Principle

This device is a light-emitting diode (LED). When a forward voltage exceeding its characteristic forward voltage (V_F) is applied, electrons and holes recombine within the semiconductor material (AlInGaP for this red LED), releasing energy in the form of photons (light). The specific composition of the semiconductor layers determines the wavelength (color) of the emitted light. The diffused lens integrated into the package scatters the light, creating the wide 100-degree viewing angle characteristic of this indicator lamp.

11. Technology Trends

While through-hole LEDs remain vital for reliability in certain applications, the broader industry trend is toward surface-mount device (SMD) packages for higher density, automated assembly, and better thermal performance. However, through-hole components like this one continue to be preferred in applications requiring high mechanical strength, ease of manual assembly/prototyping, or where point-to-point wiring is used. Advances in materials continue to improve the efficiency and longevity of all LED types, including through-hole indicators.