LTPL-C035RH660 LED Datasheet - 660nm Red - 2.1W Power - 350mA Current - English Technical Document

1. Product Overview

This document details the specifications for a high-power, surface-mount red LED emitting at a peak wavelength of 660nm. Designed for solid-state lighting applications, this component offers a combination of high radiant flux output and energy efficiency in an ultra-compact package. It is intended to provide design flexibility and reliable performance, serving as an alternative to conventional lighting technologies in various applications.

1.1 Key Features and Advantages

The LED is characterized by several key features that contribute to its performance and ease of integration:

• IC Compatibility: The device is designed to be compatible with integrated circuit drive methods, simplifying system design.
• Environmental Compliance: The component is RoHS compliant and manufactured using lead-free processes, adhering to modern environmental standards.
• Operational Efficiency: The LED technology offers lower operating costs compared to traditional light sources due to higher energy conversion efficiency.
• Reduced Maintenance: The long operational lifetime inherent to LED technology leads to significantly reduced maintenance requirements and costs over the product lifecycle.
• Compact Form Factor: The surface-mount package allows for high-density PCB layouts and streamlined assembly processes.

2. Absolute Maximum Ratings

Operating the device beyond these limits may cause permanent damage. All ratings are specified at an ambient temperature (Ta) of 25°C.

• DC Forward Current (If): 700 mA
• Power Consumption (Po): 2.1 W
• Operating Temperature Range (Topr): -40°C to +85°C
• Storage Temperature Range (Tstg): -55°C to +100°C
• Junction Temperature (Tj): 110°C

Important Note: Prolonged operation under reverse bias conditions can lead to component damage or failure. Proper circuit design must ensure the LED is not subjected to reverse voltage.

3. Electro-Optical Characteristics

The following parameters define the core performance of the LED under standard test conditions at Ta=25°C and a forward current (If) of 350mA. This is the recommended operating point.

3.1 Primary Characteristics Table

• Forward Voltage (Vf):
  • Minimum: 1.6 V
  • Typical: 2.1 V
  • Maximum: 2.6 V
• Radiant Flux (Φe): This is the total optical power output, measured with an integrating sphere.
  • Minimum: 330 mW
  • Typical: 405 mW
  • Maximum: 480 mW
• Peak Wavelength (λp): The wavelength at which the spectral emission is strongest.
  • Minimum: 650 nm
  • Maximum: 670 nm
• Viewing Angle (2θ1/2): The angular width at half the maximum luminous intensity.
  • Typical: 130°

4. Bin Code and Classification System

To ensure consistency in production and application, LEDs are sorted into performance bins based on key parameters. The bin code is marked on the product packaging.

4.1 Forward Voltage (Vf) Binning

LEDs are classified into voltage bins with a tolerance of ±0.1V at If=350mA.

• V0: 1.6V - 1.8V
• V1: 1.8V - 2.0V
• V2: 2.0V - 2.2V
• V3: 2.2V - 2.4V
• V4: 2.4V - 2.6V

4.2 Radiant Flux (Φe) Binning

LEDs are sorted by optical output power with a tolerance of ±10%.

• R2: 330 mW - 360 mW
• R3: 360 mW - 390 mW
• R4: 390 mW - 420 mW
• R5: 420 mW - 450 mW
• R6: 450 mW - 480 mW

4.3 Peak Wavelength (λp) Binning

LEDs are categorized by their dominant emission wavelength with a tolerance of ±3nm.

• P6K: 650 nm - 655 nm
• P6L: 655 nm - 660 nm
• P6M: 660 nm - 665 nm
• P6N: 665 nm - 670 nm

Note for Designers: For applications requiring specific performance consistency (e.g., color matching in arrays, precise voltage drop), specifying or requesting limited bin codes is recommended and should be discussed during the procurement process.

5. Performance Curves and Detailed Analysis

The following curves provide a deeper understanding of the LED's behavior under various operating conditions. All data is typical and measured at 25°C unless otherwise noted.

5.1 Relative Radiant Flux vs. Forward Current

This curve shows the relationship between the drive current and the light output. The radiant flux increases with current but not linearly. Operating above the recommended 350mA will yield higher output but will also increase junction temperature and accelerate lumen depreciation. The curve is essential for determining the optimal drive current for balancing brightness and longevity.

5.2 Relative Spectral Distribution

This graph depicts the intensity of light emitted across the wavelength spectrum. It confirms the monochromatic nature of the LED, with a sharp peak centered around 660nm (deep red) and a narrow spectral bandwidth. This characteristic is crucial for applications requiring specific spectral purity, such as horticultural lighting or optical sensors.

5.3 Radiation Pattern (Viewing Angle)

The polar plot illustrates the spatial distribution of light. The typical 130° viewing angle indicates a wide, lambertian-like emission pattern. This provides broad, even illumination suitable for general lighting and signage applications, as opposed to a narrow beam angle used for spotlights.

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

This fundamental curve shows the exponential relationship between voltage and current in a diode. The knee voltage is around the typical Vf of 2.1V. Understanding this curve is vital for designing the current-limiting circuitry. A small change in forward voltage can lead to a large change in current if driven by a voltage source, hence the necessity for constant-current drivers or series resistors.

5.5 Relative Radiant Flux vs. Junction Temperature

This is one of the most critical curves for thermal management design. It shows how light output decreases as the junction temperature (Tj) increases. High-power LEDs are sensitive to heat; elevated Tj reduces efficiency (lumen depreciation) and shortens lifespan. Effective heat sinking is required to maintain Tj as low as possible, ideally well below the maximum rating of 110°C, to ensure stable performance and long-term reliability.

6. Mechanical Dimensions and Package Information

The LED is housed in a surface-mount device (SMD) package. Key dimensional notes include:

• All linear dimensions are in millimeters (mm).
• General dimension tolerance is ±0.2mm.
• Tolerances for lens height and ceramic substrate length/width are tighter at ±0.1mm.
• The central thermal pad is electrically isolated (floating) from the anode and cathode electrical pads. This pad's primary function is to conduct heat away from the LED die to the printed circuit board (PCB).

The outline drawing provides exact measurements for PCB footprint design, including pad size, spacing, and component placement.

7. Assembly and Soldering Guidelines

Proper handling and soldering are critical to reliability.

7.1 Recommended Reflow Soldering Profile

A detailed temperature-time profile is provided. Key parameters typically include:

• Preheat/Ramp-up: A controlled rise to activate flux.
• Soak Zone: A plateau to ensure uniform board temperature.
• Reflow (Liquidus) Zone: The peak temperature where solder melts. The maximum package body temperature must not exceed the specified limit (often around 260°C for a short duration).
• Cooling Rate: A controlled, non-rapid cooldown is recommended to prevent thermal shock.

Important Notes: The profile may need adjustment based on solder paste specifications. Reflow soldering should be performed a maximum of three times. Hand soldering, if necessary, should be limited to 300°C for a maximum of 2 seconds per pad. Dip soldering is not recommended or guaranteed.

7.2 Recommended PCB Pad Layout

A land pattern diagram is supplied for designing the PCB. This pattern ensures proper solder joint formation, electrical connection, and most importantly, optimal thermal transfer from the LED's thermal pad to the PCB's copper plane. The size and shape of the thermal pad on the PCB are crucial for effective heat dissipation.

7.3 Cleaning and Handling

• Cleaning: Use only approved alcohol-based solvents like isopropyl alcohol (IPA). Unspecified chemicals may damage the silicone lens or package material.
• Manual Handling: Always pick up the LED by its sides, not by the lens or the wire bonds inside. Avoid touching the optical surface to prevent contamination.

8. Packaging Specifications

The LEDs are supplied in tape-and-reel packaging compatible with automated pick-and-place equipment.

• Tape Dimensions: Specifies pocket size, pitch, and cover tape details.
• Reel Dimensions: Specifies reel diameter, hub size, and orientation.
• Packing Quantities: A standard 7-inch reel holds a maximum of 500 pieces. A minimum pack quantity for remainders is 100 pieces.
• Quality: Conforms to EIA-481-1-B standards. The maximum number of consecutive missing components in the tape is two.

9. Application Notes and Design Considerations

9.1 Drive Circuit Design

LEDs are current-driven devices. For reliable operation:

• Constant Current Drive: The recommended method is to use a constant current source or driver IC. This ensures stable light output regardless of minor variations in forward voltage.
• Series Resistor (Simpler Method): When using a voltage source, a current-limiting resistor must be placed in series with each LED. The resistor value is calculated using Ohm's Law: R = (Vsupply - Vf) / If. This method is less efficient but straightforward.
• Parallel Connection Caution: Connecting multiple LEDs directly in parallel to a single current source is not recommended. Small variations in the I-V characteristics of individual LEDs (even from the same bin) can cause significant current imbalance, leading to uneven brightness and potential overcurrent in some devices. Use separate current-limiting elements per LED or connect them in series.

9.2 Thermal Management

This is paramount for high-power LEDs. Design steps include:

1. PCB Design: Use a PCB with a dedicated thermal pad connected to internal ground planes or large copper areas.
2. Vias: Incorporate an array of thermal vias under the LED's thermal pad to conduct heat to inner layers or the bottom side of the board.
3. External Heatsinking: For high-current operation or applications in high ambient temperatures, an external heatsink attached to the PCB may be necessary.
4. Monitoring: In critical applications, consider monitoring board temperature near the LED to ensure operating limits are not exceeded.

9.3 Environmental and Material Compatibility

The device has gold-plated electrodes, but caution is advised:

• Avoid using sulfur-containing materials (e.g., certain seals, gaskets, adhesives) in the final assembly, as sulfur can corrode the gold and lead to connection failure.
• Do not operate or store the product in environments with high humidity (>85% RH), condensation, salty air, or corrosive gases (Cl2, H2S, NH3, SO2, NOx).

10. Typical Application Scenarios

The 660nm red LED is suited for a variety of applications due to its specific wavelength and power:

• Horticultural Lighting: The 660nm wavelength is within the photosynthetic active radiation (PAR) range, particularly effective for promoting flowering and fruiting in plants in greenhouse or indoor farming setups.
• Automotive Lighting: Can be used in rear combination lamps (tail/stop lights), interior ambient lighting, or status indicators.
• Signage and Display Backlighting: Its high brightness and wide viewing angle make it suitable for channel letters, light boxes, and decorative lighting.
• Industrial and Machine Vision: Used as a structured light source or for illumination in optical sensing and inspection systems.
• Consumer Electronics: Status indicators, backlighting for buttons or panels in appliances and audio/video equipment.

11. Frequently Asked Questions (FAQ)

Q1: What is the difference between Radiant Flux (mW) and Luminous Flux (lm)?

A1: Radiant flux measures total optical power in watts, regardless of wavelength. Luminous flux measures perceived brightness by the human eye, weighted by the photopic vision curve (which peaks at 555nm green). For a deep red 660nm LED, the luminous efficacy (lm/W) is lower than for white or green LEDs, so radiant flux is the more relevant metric for its optical power.

Q2: Can I drive this LED at its absolute maximum current of 700mA?

A2: While possible, it is not recommended for continuous operation. Doing so will generate significantly more heat, drastically reduce efficiency (see Relative Flux vs. Temperature curve), and shorten the LED's lifespan. The recommended operating point of 350mA provides an optimal balance of output, efficiency, and longevity.

Q3: Why is the thermal pad electrically neutral?

A3: This design simplifies PCB layout and improves thermal performance. It allows the thermal pad to be connected directly to a large copper ground plane or heatsink on the PCB without creating an electrical short circuit. This maximizes heat transfer away from the LED junction.

Q4: How do I interpret the bin codes when ordering?

A4: The bin code (e.g., V2R4P6L) specifies the performance range for Voltage, Radiant Flux, and Peak Wavelength. For consistent performance in an array, you should specify a narrow or single bin for each parameter. Standard orders may receive a mix of bins within the product's overall specification.