LTPL-C034UVD375 UV LED Datasheet - 3.7x3.7x1.6mm - Voltage 3.7V - Power 2W - 375nm Peak Wavelength - English Technical Document

1. Product Overview

The product is a high-efficiency ultraviolet (UV) light-emitting diode (LED) designed primarily for UV curing processes and other common UV applications. It represents a solid-state lighting solution that aims to replace conventional UV light sources by combining the long lifetime and reliability inherent to LED technology with competitive brightness levels. This enables greater design flexibility and opens new opportunities in applications requiring UV illumination.

1.1 Key Features and Advantages

The device offers several distinct advantages over traditional UV sources:

• Integrated Circuit (IC) Compatibility: The LED is designed to be easily driven and controlled by standard electronic circuits.
• Environmental Compliance: The product is RoHS compliant and manufactured using lead-free processes.
• Operational Efficiency: It contributes to lower overall operating costs due to its energy-efficient nature.
• Reduced Maintenance: The long lifespan of LEDs significantly reduces the frequency and cost associated with lamp replacement and maintenance.

2. Technical Parameters: In-Depth Objective Interpretation

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. They are specified at an ambient temperature (Ta) of 25°C.

• DC Forward Current (If): 500 mA (Maximum)
• Power Consumption (Po): 2 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 under reverse bias conditions can lead to component failure.

2.2 Electro-Optical Characteristics

These are the typical performance parameters measured at Ta=25°C and a forward current (If) of 350mA, which appears to be the recommended operating point.

• Forward Voltage (Vf): Typical value is 3.7V, with a range from 2.8V (Min) to 4.4V (Max).
• Radiant Flux (Φe): This is the total optical power output in the UV spectrum. The typical value is 470 mW, ranging from 350 mW (Min) to 590 mW (Max).
• Peak Wavelength (λp): The wavelength at which the LED emits the most power. It ranges from 370 nm to 380 nm, centering around 375 nm.
• Viewing Angle (2θ1/2): Approximately 130 degrees, indicating a wide radiation pattern.
• Thermal Resistance (Rthjc): Junction-to-case thermal resistance is typically 14.7 °C/W. This parameter is crucial for thermal management design, as it indicates how effectively heat can be conducted away from the LED chip.

3. Binning System Explanation

The LEDs are sorted into performance bins to ensure consistency. The bin code is marked on the packaging.

3.1 Forward Voltage (Vf) Binning

LEDs are categorized into four voltage bins (V0 to V3) based on their forward voltage at 350mA. For example, bin V1 includes LEDs with Vf between 3.2V and 3.6V. The tolerance is +/- 0.1V.

3.2 Radiant Flux (Φe) Binning

Optical output power is binned from R2 (350-380 mW) up to R9 (560-590 mW). The typical bin appears to be R5 (440-470 mW). The tolerance is +/- 10%.

3.3 Peak Wavelength (Wp) Binning

The UV wavelength is binned into two groups: P3P (370-375 nm) and P3Q (375-380 nm). The tolerance is +/- 3 nm. This allows selection for applications sensitive to specific UV wavelengths.

4. Performance Curve Analysis

4.1 Relative Radiant Flux vs. Forward Current

The radiant flux increases with forward current but not linearly. Designers must balance desired optical output with electrical input power and the resulting heat generation. Operating significantly above 350mA may reduce efficiency and lifespan.

4.2 Relative Spectral Distribution

This curve shows the emission spectrum, confirming the peak in the 375nm region (UVA) and the spectral bandwidth. It is important for applications where the spectral purity or specific photon energy is critical.

4.3 Radiation Pattern

The polar diagram illustrates the 130-degree viewing angle, showing the intensity distribution. This is vital for designing optics to collect, collimate, or focus the UV light onto a target area.

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

This fundamental curve shows the exponential relationship typical of diodes. The operating point (e.g., 350mA, ~3.7V) is where the device is characterized. The curve helps in designing the appropriate current-drive circuit.

4.5 Relative Radiant Flux vs. Junction Temperature

This graph demonstrates the negative impact of rising junction temperature on light output. As temperature increases, radiant flux decreases. Effective heat sinking is therefore essential to maintain stable and high optical performance.

5. Mechanical and Package Information

5.1 Outline Dimensions

The package has a footprint of approximately 3.7mm x 3.7mm. Key dimensions include the lens height and ceramic substrate size, which have tighter tolerances (±0.1mm) compared to other features (±0.2mm). The thermal pad is electrically isolated from the anode and cathode, allowing it to be connected to a heatsink for thermal management without creating an electrical short.

5.2 Recommended PCB Attachment Pad

A land pattern design is provided for the printed circuit board (PCB). This includes the pads for the two electrical contacts (anode and cathode) and the larger central thermal pad. Proper pad design is critical for reliable soldering and effective heat transfer from the LED package to the PCB.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A detailed temperature-time profile is provided for reflow soldering. Key parameters include a peak temperature of 260°C measured on the package body, with a time above 240°C not exceeding 30 seconds. A controlled cooling rate is recommended. Hand soldering is possible but should be limited to 300°C for a maximum of 2 seconds, only once.

6.2 Important Assembly Notes

• Reflow soldering should be performed a maximum of three times.
• The lowest possible soldering temperature that achieves a reliable joint is desirable.
• Dip soldering is not a recommended or guaranteed assembly method for this component.
• Cleaning should be done only with alcohol-based solvents like isopropyl alcohol (IPA). Unspecified chemicals may damage the package.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The components are supplied on embossed carrier tape sealed with cover tape. The tape is wound onto 7-inch reels, with a maximum of 500 pieces per reel. For smaller quantities, a minimum pack of 100 pieces is available. The packaging conforms to EIA-481-1-B standards.

8. Application Suggestions

8.1 Typical Application Scenarios

• UV Curing: Adhesive curing, ink drying, resin polymerization in manufacturing processes.
• Medical & Scientific: Fluorescence analysis, sterilization (where wavelength is appropriate), phototherapy.
• Industrial: Inspection, counterfeit detection, optical sensors.

8.2 Design Considerations

• Drive Method: LEDs are current-driven devices. A constant current source is strongly recommended to ensure stable optical output and prevent thermal runaway, as the forward voltage has a negative temperature coefficient.
• Thermal Management: Given the typical 470mW of radiant flux and a total power of ~1.3W (350mA * 3.7V), over 0.8W is dissipated as heat. With a thermal resistance of 14.7°C/W, the junction temperature will rise about 11.8°C above the case temperature. Adequate heatsinking is mandatory to keep the junction below 110°C for reliability.
• Optics: The wide 130-degree beam may require secondary optics (lenses, reflectors) to achieve the desired illumination pattern on the target.
• Safety: UV radiation, especially in the UVA range, can be harmful to eyes and skin. Appropriate protective enclosures and safety warnings are necessary in the final product design.

9. Reliability and Testing

A comprehensive reliability test plan is documented, including:

• Low, Room, and High Temperature Operating Life tests.
• Wet High Temperature Operating Life test.
• Thermal Shock testing.
• Solderability and Resistance to Soldering Heat tests.

All tests reported zero failures from the sample sizes, indicating robust product construction and reliability. The criteria for judging a device as failed are a shift in forward voltage beyond ±10% or a shift in radiant flux beyond ±30% from initial values.

10. Technical Comparison and Positioning

This UV LED positions itself as an energy-efficient alternative to conventional UV sources like mercury-vapor lamps. Key differentiators include:

• Instant On/Off: Unlike lamps that require warm-up/cool-down, LEDs achieve full output instantly.
• Longevity: LED lifetimes typically far exceed those of arc lamps.
• Compact Size & Design Freedom: The small form factor enables integration into smaller devices and allows for array configurations for higher intensity or larger area coverage.
• Narrow Spectrum: The relatively narrow emission peak around 375nm can be more efficient for processes tuned to that wavelength, reducing wasted energy compared to broadband sources.

11. Frequently Asked Questions (Based on Technical Parameters)

11.1 What is the recommended operating current?

The datasheet characterizes the device at 350mA, which is likely the recommended typical operating current (It is below the absolute maximum of 500mA). Operating at this current ensures optimal performance and reliability as validated by the life tests.

11.2 How do I select the right bin for my application?

Choose based on your system's requirements: - Vf Bin: Affects driver design and power supply voltage. Tighter bins ensure more uniform current sharing in parallel arrays. - Φe Bin: Determines the optical power. Select a higher bin (e.g., R6, R7) for more intensity. - Wp Bin: Critical for processes with a specific spectral sensitivity. Choose P3P or P3Q as needed.

11.3 Why is thermal management so important?

High junction temperature directly reduces light output (as shown in the performance curves) and accelerates the degradation of the LED, shortening its lifespan. The thermal resistance value (14.7°C/W) quantifies this challenge; a lower thermal resistance path from the junction to the ambient environment is essential.

12. Practical Design and Usage Case

Case: Designing a UV Curing Spot Lamp

1. Specification: Target is to deliver >400mW of 375nm UV light onto a 10mm diameter spot for curing adhesives.
2. LED Selection: Choose an LED from the R5 (440-470mW) or higher flux bin to ensure sufficient power after optical losses.
3. Drive Circuit: Design a constant current driver set to 350mA with appropriate voltage headroom (e.g., 5V supply for a ~3.7V LED).
4. Thermal Design: Mount the LED on a metal-core PCB (MCPCB) or a dedicated heatsink. Calculate the required heatsink thermal resistance to keep the junction temperature below, for example, 85°C in a 40°C ambient environment.
5. Optics: Use a collimating or focusing lens in front of the LED to concentrate the wide 130-degree beam into the desired small spot.
6. Integration: House the assembly in a mechanically robust and thermally conductive enclosure, with safety interlocks to prevent exposure to UV light.

13. Principle Introduction

This device is a semiconductor light source. When a forward voltage is applied, electrons and holes recombine within the active region of the semiconductor chip, releasing energy in the form of photons. The specific semiconductor materials (typically involving aluminum gallium nitride - AlGaN) are engineered so that the energy bandgap corresponds to photon energies in the ultraviolet spectrum (around 375nm or 3.31 eV). The generated light is extracted through the package lens.

14. Development Trends

The field of UV LEDs is actively evolving. Trends include:p>

• Increased Efficiency: Ongoing research aims to improve the wall-plug efficiency (electrical-to-optical power conversion) of UV LEDs, particularly in the shorter wavelength UVC band for germicidal applications.
• Higher Power Density: Development of chips and packages capable of handling higher drive currents and dissipating more heat, leading to greater radiant flux from a single emitter.
• Improved Reliability: Advancements in materials and packaging technologies continue to extend operational lifetimes and stability.
• Cost Reduction: As manufacturing volumes increase and processes mature, the cost per milliwatt of UV output is expected to decrease, further accelerating the adoption of UV LEDs over traditional technologies.