LTL-R42NEWADH184 LED Lamp Datasheet - Red Diffused Lens - 2.5V - 52mW - Through Hole Package - English Technical Document

1. Product Overview

The LTL-R42NEWADH184 is a through-hole mount LED lamp assembly, specifically designed as a Circuit Board Indicator (CBI). It consists of a black plastic right-angle holder (housing) integrated with a red AlInGaP LED featuring a red diffused lens. This product is engineered for straightforward assembly onto printed circuit boards (PCBs), providing a solid-state light source for status indication and panel illumination.

1.1 Core Features and Advantages

• Ease of Assembly: The design is optimized for simple and efficient mounting on circuit boards.
• Enhanced Contrast: The black housing material improves the visual contrast ratio of the illuminated indicator.
• Solid-State Reliability: Utilizes LED technology for long operational life and robustness.
• Energy Efficiency: Characterized by low power consumption and high luminous efficiency.
• Environmental Compliance: This is a lead-free product compliant with RoHS (Restriction of Hazardous Substances) directives.
• Light Source: Employs a T-1 size AlInGaP chip emitting red light at a nominal 625nm wavelength, with a red diffused lens for wider viewing angle.

1.2 Target Applications

This component is suitable for a broad range of electronic equipment requiring reliable status indication. Primary application markets include:

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

2. In-Depth Technical Parameter Analysis

The following sections provide a detailed breakdown of the device's operational limits and performance characteristics under standard test conditions (TA=25°C).

2.1 Absolute Maximum Ratings

These ratings define the stress 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 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: The maximum continuous forward current must be linearly reduced by 0.27 mA for every degree Celsius the ambient temperature rises above 30°C.
• Operating Temperature Range: -30°C to +85°C.
• Storage Temperature Range: -40°C to +100°C.
• Lead Soldering Temperature: 260°C maximum for 5 seconds, measured at a point 2.0mm (0.079\") from the LED body.

2.2 Electrical and Optical Characteristics

These parameters define the typical performance of the device under normal operating conditions (I_F = 10mA, TA=25°C).

• Luminous Intensity (I_V): 3.8 mcd (Minimum), 18 mcd (Typical), 50 mcd (Maximum). Measurement follows the CIE photopic eye-response curve. Guaranteed values include a ±15% testing tolerance.
• Viewing Angle (2θ_1/2): 100 degrees (Typical). This is the full angle at which luminous intensity drops to half its axial (on-axis) value.
• Peak Emission Wavelength (λ_P): 630 nm (Typical). The wavelength at which the spectral power distribution is maximum.
• Dominant Wavelength (λ_d): 613.5 nm (Min), 625 nm (Typ), 633 nm (Max). This is the single wavelength perceived by the human eye to represent the color of the light, derived from CIE chromaticity coordinates.
• Spectral Line Half-Width (Δλ): 20 nm (Typical). The spectral bandwidth measured at half the maximum intensity.
• Forward Voltage (V_F): 2.0 V (Min), 2.5 V (Typ), V (Max).
• Reverse Current (I_R): 100 µA maximum at a reverse voltage (V_R) of 5V. Important Note: This device is not designed for operation under reverse bias; this test condition is for characterization only.

3. Binning System Specification

To ensure color and brightness consistency in production, LEDs are sorted into bins based on key parameters. The LTL-R42NEWADH184 uses two primary binning criteria.

3.1 Luminous Intensity Binning

Bins are defined by minimum and maximum luminous intensity values at I_F=10mA. Each bin limit has a tolerance of ±15%.

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

3.2 Dominant Wavelength (Hue) Binning

Bins are defined by minimum and maximum dominant wavelength values at I_F=10mA. Each bin limit has a tolerance of ±1nm.

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

4. Performance Curve Analysis

Typical performance curves (provided in the datasheet) illustrate the relationship between key parameters. These are essential for understanding device behavior under non-standard conditions.

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

This curve shows the exponential relationship between applied forward voltage and resulting current. It is crucial for designing the current-limiting circuitry. The typical forward voltage is 2.5V at 10mA.

4.2 Relative Luminous Intensity vs. Forward Current

This graph demonstrates how light output increases with forward current. It is generally linear within the recommended operating range but will saturate at higher currents. Designers use this to select an appropriate drive current for desired brightness.

4.3 Relative Luminous Intensity vs. Ambient Temperature

LED light output decreases as junction temperature increases. This curve quantifies the thermal derating of luminous intensity, highlighting the importance of thermal management in high-reliability or high-brightness applications.

4.4 Spectral Power Distribution

This plot shows the relative radiant power emitted as a function of wavelength. It confirms the peak wavelength (630nm typical) and spectral half-width (20nm typical), defining the precise red color point of the LED.

5. Mechanical and Packaging Information

5.1 Outline Dimensions and Construction

• Holder Material: Plastic, black or dark gray.
• LED: Red AlInGaP chip with a red diffused lens (T-1 size).
• Tolerances: All dimensions have a standard tolerance of ±0.25mm (0.010\") unless otherwise specified on the dimensional drawing.

5.2 Packaging Specification

The device is supplied on tape-and-reel for automated assembly.

• Carrier Tape: Black conductive polystyrene alloy, 0.50mm ±0.06mm thick.
• Reel: Standard 13-inch reel.
• Quantity per Reel: 400 pieces.
• Master Carton: 2 reels (800 pcs) are packed in a Moisture Barrier Bag (MBB) with desiccant and a humidity indicator card. 10 of these inner cartons are packed into one outer carton, totaling 8,000 pieces.

6. Soldering and Assembly Guidelines

Adherence to these guidelines is critical to prevent mechanical or thermal damage during the manufacturing process.

6.1 Storage

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

6.2 Cleaning

If cleaning is necessary, use only alcohol-based solvents such as isopropyl alcohol. Avoid harsh or abrasive chemicals.

6.3 Lead Forming

If leads require bending, perform this operation before soldering and at room temperature. The bend must be made at a point at least 3mm from the base of the LED lens. Do not use the lens base or lead frame as a fulcrum. Apply minimal force during PCB insertion to avoid stress.

6.4 Soldering Process

Critical Rule: Maintain a minimum distance of 2mm between the solder point and the base of the lens/holder. Never immerse the lens or holder into solder.

• Hand Soldering (Iron): Maximum temperature 350°C. Maximum soldering time 3 seconds per lead. Perform only once.
• Wave Soldering: Maximum pre-heat temperature 160°C for up to 120 seconds. Maximum solder wave temperature 265°C for a maximum of 10 seconds. Ensure the PCB is oriented so the solder wave does not come closer than 2mm to the lens base.

Warning: Excessive temperature or time can cause lens deformation or catastrophic LED failure. The maximum wave soldering temperature is not indicative of the holder's Heat Deflection Temperature (HDT) or melting point.

7. Application Design Considerations

7.1 Drive Circuit Design

LEDs are current-operated devices. Their forward voltage (V_F) has a tolerance and a negative temperature coefficient. To ensure uniform brightness, especially when connecting multiple LEDs in parallel, it is strongly recommended to use a series current-limiting resistor for each LED (Circuit Model A).

Circuit Model A (Recommended): [Power Supply] -> [Resistor] -> [LED] -> [Ground]. This configuration compensates for variations in individual LED V_F.

Circuit Model B (Not Recommended for Parallel): Connecting multiple LEDs in parallel to a single current-limiting resistor (or constant voltage source) is discouraged. Small differences in the I-V characteristics of each LED can cause significant current imbalance, leading to uneven brightness and potential over-stress of one device.

7.2 Electrostatic Discharge (ESD) Protection

While not explicitly rated for ESD in this datasheet, AlInGaP LEDs can be sensitive to electrostatic discharge. Standard ESD handling precautions should be observed during assembly and handling, including the use of grounded workstations and wrist straps.

7.3 Thermal Management

Although power dissipation is low (52mW max), the derating curve shows luminous intensity decreases with rising temperature. For consistent performance, especially in high ambient temperature environments or at higher drive currents, consider PCB layout to allow for some heat dissipation through the leads.

8. Technical Comparison and Positioning

The LTL-R42NEWADH184 differentiates itself through its integrated right-angle holder design, which simplifies assembly and provides a consistent mounting height and orientation. Compared to discrete LEDs that require separate mounting hardware, this integrated CBI (Circuit Board Indicator) solution offers:

• Reduced Assembly Complexity: Single component placement versus multiple parts.
• Improved Aesthetics and Consistency: Uniform black housing enhances contrast and provides a clean, professional appearance on the PCB.
• Robustness: The holder protects the LED lens and provides mechanical stability.
• Standardized Footprint: Simplifies PCB layout design.

9. Frequently Asked Questions (Based on Technical Parameters)

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

Peak Wavelength (λ_P): The specific wavelength where the LED emits the most optical power (630nm typical). Dominant Wavelength (λ_d): The single wavelength that best matches the color perceived by the human eye (625nm typical). λ_d is calculated from the CIE color coordinates and is more relevant for color specification.

9.2 Can I drive this LED at 20mA continuously?

Yes, 20mA is the maximum rated continuous DC forward current at an ambient temperature of 25°C. However, if the ambient temperature exceeds 30°C, you must derate the current according to the specified rate of 0.27 mA/°C. For example, at 50°C ambient, the maximum allowable continuous current would be 20mA - (0.27mA/°C * (50°C-30°C)) = 14.6mA.

9.3 Why is a series resistor necessary even with a constant voltage supply?

The forward voltage of an LED is not a fixed value like a Zener diode; it has production tolerance and decreases with increasing temperature. A series resistor acts as a simple, stable current regulator. Without it, a small change in supply voltage or LED V_F (due to temperature or bin variation) can cause a large change in current, drastically affecting brightness and potentially exceeding maximum ratings.

10. Practical Application Example

Scenario: Designing a power-on indicator for a device operating from a 5V DC rail. The desired brightness is in the mid-range of the LED's capability.

1. Select Drive Current: Choose I_F = 10mA, which is a standard test condition and provides good brightness with long life.
2. Determine LED Forward Voltage: Use the typical value from the datasheet, V_F = 2.5V.
3. Calculate Series Resistor: R = (V_supply - V_F) / I_F = (5V - 2.5V) / 0.010A = 250 Ohms.
4. Select Standard Resistor Value: Choose the nearest standard value, e.g., 240 Ohms or 270 Ohms. Recalculating current with 240 Ohms: I_F = (5V - 2.5V) / 240Ω ≈ 10.4mA (acceptable).
5. Calculate Resistor Power: P = I² * R = (0.0104A)² * 240Ω ≈ 0.026W. A standard 1/8W (0.125W) or 1/10W resistor is more than sufficient.
6. PCB Layout: Place the resistor in series with the LED's anode or cathode. Ensure the LED is oriented correctly (typically, the longer lead is the anode). Maintain the 2mm clearance from the lens base to the solder pad on the PCB layout.

11. Operational Principle

The LTL-R42NEWADH184 is based on a semiconductor AlInGaP (Aluminum Indium Gallium Phosphide) LED chip. When a forward voltage exceeding the chip's bandgap voltage is applied, electrons and holes recombine in the active region of the semiconductor, releasing energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy, which directly corresponds to the wavelength (color) of the emitted light—in this case, red (~625nm). The integrated red diffused lens serves to extract the light from the semiconductor chip, shape the beam into a wide viewing angle (100°), and diffuse the light source to appear softer and more uniform.

12. Technology Trends

While through-hole LEDs like the LTL-R42NEWADH184 remain vital for applications requiring robust mechanical mounting or manual assembly, the broader LED industry trend is towards surface-mount device (SMD) packages. SMD LEDs offer significant advantages in automated assembly speed, board space savings, and lower profile. However, through-hole components continue to be preferred in scenarios demanding very high mechanical bond strength (e.g., connectors subject to frequent mating), in high-vibration environments, or for prototyping and repair where manual soldering is common. The integrated holder design of this product represents an evolution within the through-hole segment, adding value through ease of use and improved aesthetics.