LTPL-G35UVC275PR UVC LED Datasheet - Dimensions 3.5x3.5x1.2mm - Voltage 5.9V Typ - Power 2.0W Max - 274nm Peak Wavelength - English Technical Documentation

1. Product Overview

The LTPL-G35UVC product series represents a significant advancement in solid-state ultraviolet light sources designed for sterilization and medical applications. This product combines the inherent benefits of Light Emitting Diode (LED) technology, such as long operational lifetime and high reliability, with performance levels suitable for displacing conventional ultraviolet light sources. It is engineered to provide design flexibility and enable new applications in areas requiring effective UVC irradiation.

Key features of this product include its compatibility with integrated circuit (I.C.) drive systems, compliance with RoHS (Restriction of Hazardous Substances) directives ensuring it is lead-free, and overall lower operating and maintenance costs compared to traditional UV technologies like mercury lamps. The primary target market includes equipment manufacturers in the medical device, water purification, air sterilization, and surface disinfection sectors.

2. Technical Parameters Deep Objective Interpretation

2.1 Absolute Maximum Ratings

The device is specified for operation under strict environmental and electrical limits to ensure reliability. The absolute maximum ratings, measured at an ambient temperature (Ta) of 25°C, define the boundaries beyond which permanent damage may occur.

• Power Dissipation (Po): Maximum 2.0 Watts. This is the total power the package can dissipate as heat.
• DC Forward Current (IF): Maximum 300 milliamperes.
• Operating Temperature Range (Topr): -40°C to +80°C. The device is rated to function within this broad temperature window.
• Storage Temperature Range (Tstg): -40°C to +100°C.
• Junction Temperature (Tj): Maximum 105°C. The temperature at the semiconductor chip itself must not exceed this limit.

A critical note warns against operating the LED under reverse bias conditions for extended periods, as this can lead to component failure.

2.2 Electro-Optical Characteristics

The core performance metrics are defined at Ta=25°C and a test current (If) of 250mA, which is considered a typical operating point.

• Forward Voltage (Vf): Typical value is 5.9V, with a minimum of 5.2V and a maximum of 7.7V. Measurement tolerance is ±0.1V.
• Radiant Flux (Φe): This is the total optical power output in the UVC spectrum. The typical value is 35.0 milliwatts (mW), with a minimum of 25.0 mW. Measurement tolerance is ±10%.
• Peak Wavelength (λp): The wavelength at which the LED emits the most optical power. The typical value is 274 nanometers (nm), within a range from 265nm to 280nm. Tolerance is ±3nm. This places it firmly in the UVC band (200-280nm), known for its germicidal effectiveness.
• Viewing Angle (2θ1/2): Typically 120 degrees, defining the angular spread of the emitted radiation.
• Thermal Resistance (Rth j-s): The thermal resistance from the semiconductor junction to the solder point is typically 16.8 K/W. This parameter is crucial for thermal management design. The reference measurement uses a specific aluminum Metal Core Printed Circuit Board (MCPCB).
• Electrostatic Discharge (ESD) Sensitivity: Withstands up to 2000V per the Human Body Model (JESD22-A114-B), indicating moderate ESD robustness but still requiring careful handling.

3. Binning System Explanation

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

3.1 Forward Voltage (Vf) Binning

LEDs are categorized into five bins (V1 to V5) based on their forward voltage at 250mA. Each bin covers a 0.5V range, from 5.2-5.7V (V1) up to 7.2-7.7V (V5). Tolerance within each bin is ±0.1V. This allows designers to select LEDs with similar electrical characteristics for parallel connections or current-sharing circuits.

3.2 Radiant Flux (Φe) Binning

Optical output power is binned into four categories (X1 to X4). The X2 bin, for example, covers LEDs with radiant flux between 30.0 mW and 35.0 mW at 250mA. The X4 bin specifies a minimum of 40.0 mW. Tolerance is ±7%. This binning is essential for applications requiring a specific minimum irradiance dose.

3.3 Peak Wavelength (Wp) Binning

Currently, all devices fall into a single wavelength bin, W1, which spans from 265nm to 280nm. The tolerance is ±3nm. This ensures all devices emit within the effective germicidal range.

4. Performance Curve Analysis

The datasheet provides several graphs illustrating device behavior under varying conditions. All curves are based on a 25°C ambient temperature unless specified otherwise.

4.1 Relative Radiant Flux vs. Forward Current

This curve shows that the optical output increases with drive current but is not perfectly linear. It demonstrates the relationship between electrical input and optical output, helping to determine the optimal operating point for efficiency and output.

4.2 Relative Spectral Distribution

This graph depicts the emission spectrum, showing the intensity of light across different wavelengths. It confirms the peak emission around 274nm and the spectral bandwidth, which is important for understanding the LED's effectiveness against specific microorganisms.

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

The fundamental electrical characteristic of a diode. This curve is essential for designing the current drive circuit, as it shows the voltage required to achieve a desired current.

4.4 Relative Radiant Flux vs. Junction Temperature

This critical curve shows how optical output decreases as the junction temperature (Tj) increases. Effective thermal management is paramount to maintaining high output power over the LED's lifetime.

4.5 Radiation Characteristics (Spatial Distribution)

A polar plot illustrating the angular intensity distribution, confirming the 120-degree viewing angle. This is vital for optical system design to ensure uniform irradiation of a target surface.

4.6 Forward Current Derating Curve

This graph defines the maximum allowable forward current as a function of the ambient temperature. As temperature rises, the maximum safe current decreases to prevent the junction temperature from exceeding its 105°C limit.

4.7 Forward Voltage vs. Junction Temperature

Shows the relationship between forward voltage and the temperature of the semiconductor junction, which can be used for indirect temperature monitoring or understanding temperature-dependent behavior.

5. Mechanical and Packaging Information

5.1 Outline Dimensions

The LED package has a square footprint. All dimensions are provided in millimeters with a standard tolerance of ±0.2mm unless otherwise noted. The physical size is a key factor for PCB layout and integration into final products.

5.2 Recommended PCB Attachment Pad

A detailed land pattern diagram is provided for the Printed Circuit Board (PCB). Adhering to these recommended pad dimensions and spacing is crucial for achieving reliable solder joints, proper thermal transfer, and mechanical stability. The specification tolerance for the pad is ±0.1mm.

5.3 Polarity Identification

The datasheet includes markings or diagrams indicating the anode and cathode connections. Correct polarity must be observed during assembly to prevent damage.

6. Soldering and Assembly Guidelines

6.1 Suggested Reflow Soldering Profile

A detailed reflow profile for lead-free solder assembly is specified. Key parameters include:

• Peak Temperature (Tp): 260°C maximum (245°C recommended).
• Time above liquidus (217°C): 60-150 seconds.
• Preheat temperature: 150-200°C for 60-120 seconds.
• Maximum ramp-up and ramp-down rates are defined to minimize thermal stress.

The total time from 25°C to peak temperature should not exceed 8 minutes. Reflow soldering should be performed a maximum of three times.

6.2 Hand Soldering

If hand soldering is necessary, the iron tip temperature should not exceed 300°C, and contact time should be limited to 2 seconds maximum, for only one operation.

6.3 Cleaning

If cleaning is required after soldering, only alcohol-based solvents like isopropyl alcohol should be used. Unspecified chemical cleaners may damage the LED package.

6.4 Drive Method

The LED is a current-operated device. To ensure uniform light output when connecting multiple LEDs, they should be driven in a series configuration or using individual current regulators for each parallel branch. Constant current drivers are strongly recommended over constant voltage sources.

7. Packaging and Ordering Information

7.1 Tape and Reel Packaging

The LEDs are supplied in embossed carrier tape on reels for automated assembly. Key packaging specifications include:

• Reel Size: 7 inches.
• Maximum Quantity per Reel: 500 pieces.
• Minimum Packing Quantity: 100 pieces for remainders.
• The tape is sealed with a top cover.
• Packaging conforms to EIA-481-1-B standards.

Detailed dimensions for both the tape pockets and the reel are provided in the datasheet.

8. Application Suggestions

8.1 Typical Application Scenarios

• Surface Disinfection: Integration into devices for sanitizing mobile phones, tools, or countertops.
• Water Purification: Used in point-of-use or point-of-entry water treatment systems to inactivate bacteria and viruses.
• Air Sterilization: Implementation in HVAC systems, air purifiers, or upper-room air disinfection fixtures.
• Medical Equipment Sterilization: For disinfecting the interior chambers of devices or tools.

8.2 Design Considerations

• Thermal Management: Due to the typical 16.8 K/W thermal resistance, a properly designed heatsink (using an MCPCB as a reference) is essential to maintain junction temperature within limits and ensure long-term radiant flux output.
• Optical Design: The 120-degree viewing angle may require reflectors or lenses to collimate or direct the UVC light onto the target area efficiently.
• Electrical Design: Use a constant current driver suitable for the forward voltage range (5.2V-7.7V) and capable of delivering up to 300mA. Consider binning for multi-LED designs.
• Material Compatibility: Ensure that housing materials exposed to UVC radiation are resistant to degradation (e.g., certain plastics may yellow or become brittle).
• Safety: UVC radiation is harmful to eyes and skin. Designs must incorporate appropriate shielding, interlocks, and warnings to prevent human exposure.

9. Reliability and Testing

9.1 Reliability Test Plan

The product undergoes a comprehensive suite of reliability tests to ensure robustness under various stress conditions. Key tests include:

• Room Temperature Operating Life (RTOL): 3,000 hours at 250mA and 1,000 hours at the maximum 300mA current.
• High/Low Temperature Storage Life (HTSL/LTSL): 1,000 hours at 100°C and -40°C, respectively.
• Wet High Temperature Storage (WHTSL): 1,000 hours at 60°C and 90% relative humidity.
• Thermal Shock (TS): 100 cycles between -30°C and 85°C.

All operating life tests are conducted with the LED mounted on a specified metal heat sink.

9.2 Failure Criteria

A device is considered to have failed if, after testing, its forward voltage increases by more than 10% from the initial value, or if its radiant flux drops below 50% of the initial measurement, both measured at 250mA.

10. Technical Comparison and Advantages

Compared to traditional germicidal lamps (e.g., low-pressure mercury lamps emitting at 254nm), this UVC LED offers several distinct advantages:

• Instant On/Off: LEDs reach full output immediately, unlike lamps which require warm-up time.
• Compact Size and Design Freedom: The small form factor enables integration into portable and spatially constrained devices.
• Durability and Lifetime: Solid-state construction makes them more resistant to vibration and physical shock. While lifetime data is provided via reliability testing, LEDs generally offer longer operational life than conventional lamps when properly heatsunk.
• Mercury-Free: Contains no hazardous mercury, simplifying disposal and improving environmental safety.
• Wavelength Flexibility: The 274nm peak wavelength can be effective against a broad range of pathogens. The narrow spectrum allows for targeted applications without unnecessary radiation.
• Lower Operating Costs: Higher efficiency and longer life contribute to reduced energy and replacement costs over time.

11. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the typical operating current for this LED?

A: The electro-optical characteristics are specified at 250mA, which is a common operating point. The absolute maximum current is 300mA.

Q: How do I ensure multiple LEDs have the same brightness?

A: Use the binning information. Select LEDs from the same Radiant Flux (Φe) bin (e.g., X2) and drive them with an identical current, preferably in a series configuration or with individual current regulation for parallel strings.

Q: Why is thermal management so important for this LED?

A: As shown in the \"Relative Radiant Flux vs. Junction Temperature\" curve, optical output decreases significantly as temperature rises. Exceeding the maximum junction temperature (105°C) can also lead to accelerated degradation and premature failure. Proper heatsinking is non-negotiable for performance and reliability.

Q: Can I drive this LED with a constant voltage power supply?

A: It is not recommended. LEDs are current-driven devices. A small change in forward voltage (as seen in the Vf binning) can cause a large change in current due to the diode's exponential I-V characteristic, leading to inconsistent output and potential overcurrent damage. Always use a constant current driver.

Q: What materials are safe to use near the LED's output window?

A: UVC radiation degrades many organic materials. Use UVC-resistant materials such as certain grades of quartz glass, PTFE (Teflon), or specialized UVC-stable plastics for lenses, windows, and housing components in the light path.

12. Design and Usage Case Study

Scenario: Designing a Portable Water Sterilization Bottle.

A designer is creating a reusable water bottle with integrated UVC sterilization. The LTPL-G35UVC275PR is selected for its compact size and 274nm output.

Implementation:

1. Electrical Design: A small, rechargeable lithium battery powers a boost converter/constant current driver set to 250mA to drive a single LED in series with the driver.

2. Thermal Design: The LED is mounted on a small, custom aluminum MCPCB which is thermally bonded to the inner metal wall of the bottle's chamber, using it as a passive heatsink.

3. Optical Design: The LED's 120-degree beam is used to irradiate the water volume directly. A reflective coating on the chamber walls improves uniformity.

4. Safety Design: The circuit includes a timer to ensure a sufficient dose (e.g., 60 seconds) is delivered. A mechanical interlock prevents the LED from activating if the bottle cap is not fully sealed, and the chamber is opaque to block UVC leakage.

5. Component Selection: LEDs from the X2 or X3 flux bin are chosen to guarantee a minimum radiant output, and the driver is specified to handle the V1-V5 voltage range.

13. Principle Introduction

UVC Light Emitting Diodes operate on the principle of electroluminescence in semiconductor materials. When a forward voltage is applied across the p-n junction, electrons and holes recombine, releasing energy in the form of photons. The wavelength of these photons is determined by the bandgap energy of the semiconductor material. For UVC emission (200-280nm), materials like aluminum gallium nitride (AlGaN) are used. The specific composition of the AlGaN layers is engineered to produce a peak emission at 274nm, which corresponds to a photon energy of approximately 4.52 electron volts (eV). This high-energy ultraviolet light is absorbed by the DNA and RNA of microorganisms, causing thymine dimers which disrupt replication and lead to inactivation or death of the cell, providing the germicidal effect.

14. Development Trends

The field of UVC LEDs is rapidly evolving. Key trends observable from this datasheet and the broader market include:

• Increasing Output Power: Devices like the LTPL-G35UVC275PR, with tens of milliwatts of output, represent progress from earlier, lower-power generations. Continued development aims for higher radiant flux from a single package.
• Improved Efficiency (Wall-Plug Efficiency): Research focuses on reducing the forward voltage and increasing the external quantum efficiency (the ratio of output photons to input electrons) to lower power consumption and thermal load.
• Enhanced Reliability and Lifetime: Ongoing materials science and packaging innovation aim to push the operational lifetime further, making UVC LEDs more competitive with traditional lamps in high-duty-cycle applications.
• Cost Reduction: As manufacturing volumes increase and processes mature, the cost per milliwatt of UVC output is expected to decrease, opening up new mass-market applications.
• Wavelength Optimization: Research continues into the most effective wavelengths for inactivating specific pathogens (e.g., viruses vs. bacteria) and developing LEDs that emit at those optimal wavelengths.

These trends are driving the adoption of solid-state UVC technology across an expanding range of sterilization and purification applications.