LTPL-C035RH730 IR LED Datasheet - 3.5x3.5mm Package - 2.0V Typ - 1.96W Max - 730nm Peak Wavelength - English Technical Document

1. Product Overview

The LTPL-C035RH730 is a high-power, energy-efficient infrared light-emitting diode (LED) designed for solid-state lighting applications. This device represents an advanced light source technology that combines the long operational lifetime and reliability inherent to LEDs with significant radiant output. It is engineered to provide design flexibility and performance suitable for displacing conventional infrared lighting technologies in various applications.

1.1 Key Features and Advantages

The LED incorporates several features that enhance its usability and performance in electronic designs:

• Integrated Circuit Compatibility: The device is designed to be directly compatible with standard integrated circuit drive levels and logic, simplifying interface design.
• Environmental Compliance: The component is compliant with RoHS (Restriction of Hazardous Substances) directives and is manufactured using lead-free (Pb-free) processes.
• Operational Efficiency: The LED offers lower operating costs compared to traditional infrared sources due to its higher electrical-to-optical conversion efficiency.
• Reduced Maintenance: The extended lifetime and robust solid-state construction contribute to significantly reduced maintenance costs and downtime over the product lifecycle.

2. Technical Specifications Deep Dive

This section provides a detailed, objective analysis of the LED's key technical parameters as defined 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. Continuous operation at or near these limits is not advised and can affect reliability.

• DC Forward Current (If): 700 mA (Maximum)
• Power Consumption (Po): 1.96 W (Maximum)
• Operating Temperature Range (Topr): -40°C to +85°C
• Storage Temperature Range (Tstg): -55°C to +100°C
• Junction Temperature (Tj): 110°C (Maximum)

Important Note: Prolonged operation of the LED under reverse bias conditions can lead to component damage or failure. Proper circuit design should include protection against reverse voltage.

2.2 Electro-Optical Characteristics

Measured at a typical drive current of 350mA and an ambient temperature of 25°C, these parameters define the core performance of the LED.

• Forward Voltage (Vf):
  • Minimum: 1.6 V
  • Typical: 2.0 V
  • Maximum: 2.4 V
• Radiant Flux (Φe): This is the total optical power output, measured in milliwatts (mW) using an integrating sphere.
  • Minimum: 230 mW
  • Typical: 250 mW
  • Maximum: 310 mW
• Peak Wavelength (Wp): The wavelength at which the spectral radiant intensity is maximum.
  • Minimum: 720 nm
  • Maximum: 740 nm
  • The part number '730' indicates a nominal peak wavelength of 730nm.
• Viewing Angle (2θ1/2): The full angle at which the radiant intensity is half of the maximum intensity (typically measured from the optical axis).
  • Typical: 130°

3. Bin Code and Classification System

The LEDs are sorted (binned) based on key performance parameters to ensure consistency within a batch. The bin code is marked on each packing bag.

3.1 Forward Voltage (Vf) Binning

LEDs are categorized into four voltage bins (V0 to V3) with a tolerance of ±0.1V at 350mA.

• V0: 1.6V – 1.8V
• V1: 1.8V – 2.0V
• V2: 2.0V – 2.2V
• V3: 2.2V – 2.4V

3.2 Radiant Flux (Φe) Binning

LEDs are sorted into four radiant flux bins (R0 to R3) with a tolerance of ±10% at 350mA.

• R0: 230 mW – 250 mW
• R1: 250 mW – 270 mW
• R2: 270 mW – 290 mW
• R3: 290 mW – 310 mW

3.3 Peak Wavelength (Wp) Binning

LEDs are classified into four wavelength bins (P7E to P7H) with a tolerance of ±3nm at 350mA.

• P7E: 720 nm – 725 nm
• P7F: 725 nm – 730 nm
• P7G: 730 nm – 735 nm
• P7H: 735 nm – 740 nm

Special or limited bin requests require direct consultation.

4. Performance Curve Analysis

The following typical curves, measured at 25°C unless specified, provide insight into the LED's behavior under varying conditions.

4.1 Relative Radiant Flux vs. Forward Current

This graph shows how the optical output (radiant flux) increases with forward current. It is typically non-linear, with efficiency (radiant flux per unit current) often decreasing at very high currents due to increased thermal effects and internal losses. Designers use this to select an optimal operating point that balances output and efficiency.

4.2 Relative Spectral Distribution

This plot illustrates the intensity of light emitted across different wavelengths, centered around the peak wavelength (730nm). It shows the spectral width or bandwidth of the emission. A narrower spectrum is typical for monochromatic LEDs like this infrared device.

4.3 Radiation Pattern (Characteristics)

This polar diagram depicts the spatial distribution of light intensity around the LED, defining its viewing angle of 130°. The pattern influences how light is distributed in an application, such as for uniform illumination or directed sensing.

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

This fundamental curve shows the relationship between the voltage applied across the LED and the resulting current flow. It demonstrates the diode's exponential characteristic. The typical forward voltage (Vf) is specified at a given current (350mA). The curve is essential for designing the current-limiting circuitry.

4.5 Relative Radiant Flux vs. Junction Temperature

This critical graph shows how the optical output decreases as the LED's junction temperature (Tj) increases. This thermal derating is a key characteristic of all LEDs. Effective thermal management (heat sinking) is crucial to maintain stable, long-term light output and to prevent accelerated degradation.

5. Mechanical and Package Information

5.1 Outline Dimensions

The LED features a compact surface-mount package. Key dimensional notes include:

• All dimensions are in millimeters (mm).
• General dimension tolerance is ±0.2mm.
• Lens height and ceramic substrate length/width have a tighter tolerance of ±0.1mm.
• The thermal pad on the bottom of the device is electrically isolated (neutral) from the anode and cathode electrical pads. This allows it to be connected directly to a PCB ground plane for heat dissipation without creating an electrical short.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A recommended reflow soldering profile is provided. Critical parameters include:

• Peak Temperature: Specified (refer to profile curve). All temperatures refer to the top side of the package body.
• Time Above Liquidus (TAL): Defined by the profile.
• Ramp Rates: Controlled heating and cooling rates are specified. A rapid cooling process is not recommended.

Important Notes: The profile may need adjustment based on specific solder paste characteristics. The lowest possible soldering temperature that achieves a reliable joint is always desirable to minimize thermal stress on the LED. The device is not guaranteed if assembled using dip soldering methods.

6.2 Recommended PCB Pad Layout

A land pattern design is suggested for the printed circuit board to ensure proper soldering and mechanical stability.

• Soldering Methods: Reflow or hand soldering can be used.
• Hand Soldering: Maximum 300°C for a maximum of 2 seconds, once only.
• Reflow Limit: The LED should not undergo reflow soldering more than three times.

6.3 Cleaning

If cleaning is necessary after soldering, only alcohol-based solvents like isopropyl alcohol (IPA) should be used. Unspecified chemical cleaners can damage the LED package material and optical components.

7. Reliability and Testing

A comprehensive reliability test plan validates the LED's robustness under various environmental and operational stresses. All tests listed showed 0 failures out of 10 samples.

7.1 Reliability Test Summary

• Low/High Temperature Operating Life (LTOL/HTOL): Tests operation at -10°C, 25°C, and 85°C for 1000 hours.
• Wet High Temperature Operating Life (WHTOL): 60°C/90% Relative Humidity for 500 hours.
• Thermal Shock (TMSK): 100 cycles between -40°C and 125°C.
• High Temperature Storage: 1000 hours at 100°C.
• Solderability & Reflow Resistance: Tests for soldering heat resistance (260°C for 10s) and solder wetting.

7.2 Failure Criteria

Post-test, devices are judged against strict limits:

• Forward Voltage (Vf): Must remain within ±10% of the initial typical value.
• Radiant Flux (Φe): Must remain within ±15% of the initial typical value.

8. Packaging and Handling

8.1 Tape and Reel Specifications

The LEDs are supplied in embossed carrier tape on reels for automated assembly.

• Empty pockets in the tape are sealed with a cover tape.
• A standard 7-inch (178mm) reel can hold a maximum of 500 pieces.
• A maximum of two consecutive missing components (empty pockets) is allowed per specification.
• Packaging conforms to EIA-481-1-B standards.

9. Application Notes and Design Considerations

9.1 Drive Method

Critical Design Rule: An LED is a current-operated device. Its light output is primarily a function of forward current (If), not voltage. To ensure intensity uniformity when connecting multiple LEDs in parallel in an application, each LED or parallel string should be driven by a dedicated current-limiting mechanism (e.g., a resistor or, preferably, a constant current driver). Relying solely on the natural Vf matching of LEDs in parallel can lead to significant current imbalance and uneven brightness due to the steep I-V curve and manufacturing variances.

9.2 Thermal Management

As indicated by the Radiant Flux vs. Junction Temperature curve, performance is highly temperature-dependent. For reliable, long-term operation at high drive currents (e.g., near 350mA or above), effective heat sinking is mandatory. This involves:

• Using the designated thermal pad to conduct heat away from the LED die.
• Designing the PCB with adequate thermal vias and copper pours connected to the thermal pad.
• Considering the overall system airflow and ambient temperature.

9.3 Typical Application Scenarios

With a peak wavelength of 730nm in the near-infrared (NIR) spectrum, this LED is suited for applications including but not limited to:

• Machine Vision & Inspection: Illumination for IR-sensitive cameras in industrial automation.
• Security & Surveillance: Covert illumination for night-vision CCTV systems.
• Biometric Sensors: Used in devices like heart rate monitors or proximity sensors.
• Optical Switches & Encoders: As a light source in interruptive or reflective sensors.
• General IR Illumination: For scientific, agricultural, or specialty lighting needs.

10. Technical Comparison and Positioning

This LED differentiates itself through its combination of parameters:

• High Radiant Flux: Output up to 310mW at 350mA places it in the mid-to-high power category for IR LEDs, suitable for applications requiring substantial IR illumination.
• Wide Viewing Angle: The 130° viewing angle provides broad, diffuse illumination ideal for covering large areas or for applications where the exact alignment of source and detector is not critical.
• Robust Package & Reliability: The ceramic-based package and comprehensive reliability testing indicate suitability for industrial and demanding environments.
• Specific Wavelength: The 730nm wavelength is a common choice for silicon-based photodetectors, which have good sensitivity in this range, making it a practical system-level choice.

11. Frequently Asked Questions (Based on Technical Parameters)

11.1 What is the difference between Radiant Flux and Luminous Flux?

Radiant Flux (Φe, measured in Watts) is the total optical power emitted across all wavelengths. Luminous Flux (measured in Lumens) weights this power by the sensitivity of the human eye. Since this is an infrared LED invisible to humans, its performance is correctly specified in Radiant Flux (mW).

11.2 Can I drive this LED at the maximum current of 700mA continuously?

The Absolute Maximum Rating of 700mA is a stress limit. Continuous operation at this current would likely cause the junction temperature to exceed its maximum rating of 110°C unless exceptional cooling is provided, leading to rapid degradation. The typical operating condition is 350mA. Any design near the maximum rating requires meticulous thermal analysis and heat sinking.

11.3 How do I interpret the Bin Codes when ordering?

For consistent performance in a batch, specify the required bins for Vf, Φe, and Wp. For example, requesting V1 (1.8-2.0V), R2 (270-290mW), and P7G (730-735nm) ensures all LEDs in your order have tightly grouped electrical and optical characteristics. If no bin is specified, you will receive LEDs from the standard production distribution across all bins.

12. Operational Principles and Technology Trends

12.1 Basic Operating Principle

An infrared LED is a semiconductor p-n junction diode. When a forward voltage is applied, electrons and holes are injected into the junction region where they recombine. In this specific LED material system, a significant portion of this recombination energy is released as photons (light) in the infrared spectrum, with a peak wavelength determined by the energy bandgap of the semiconductor materials used (typically based on Aluminum Gallium Arsenide - AlGaAs).

12.2 Industry Trends

The solid-state lighting trend continues to advance, with IR LEDs seeing improvements in:

• Wall-Plug Efficiency (WPE): The ratio of radiant flux output to electrical power input, driving lower energy consumption for the same optical power.
• Power Density: Development of packages that can handle higher drive currents and dissipate more heat, enabling smaller, brighter sources.
• Spectral Control: Tighter wavelength tolerances and the development of LEDs at specific wavelengths for applications like gas sensing or optical communications.
• Integration: Combining multiple LED chips, drivers, and optics into modular or smart lighting systems.