UVC LED LTPL-G35UVC275GS Datasheet - 3.5x3.5mm - 5.0-7.0V - 275nm Peak Wavelength - 0.7W Max Power - English Technical Document

1. Product Overview

The LTPL-G35UVC275GS is a high-performance ultraviolet-C (UVC) light-emitting diode (LED) designed specifically for sterilization and medical applications. This product represents a significant advancement in solid-state lighting technology, offering a reliable and energy-efficient alternative to conventional UV light sources such as mercury lamps. The device operates in the germicidal wavelength range, typically around 275 nanometers, which is highly effective for inactivating microorganisms including bacteria and viruses.

This LED series combines the inherent benefits of LED technology—such as long operational lifetime, instant on/off capability, and compact form factor—with the specific optical output required for effective disinfection. It enables greater design freedom for engineers developing sterilization equipment, air purifiers, water treatment systems, and medical devices. By displacing older UV technologies, it contributes to systems with lower operating costs, reduced maintenance requirements, and improved environmental profiles due to the absence of mercury.

1.1 Core Advantages and Target Market

The primary advantages of this UVC LED include its compatibility with integrated circuit (IC) drive systems, compliance with RoHS (Restriction of Hazardous Substances) directives, and its lead-free construction. These features make it suitable for integration into modern electronic products with strict regulatory and environmental requirements. The target markets are primarily the healthcare, consumer appliance, and industrial equipment sectors where effective and reliable surface, air, or water disinfection is critical. Applications range from portable sterilizers and HVAC systems to specialized medical instrument cleaners.

2. Technical Parameter Deep-Dive Analysis

The performance of the LTPL-G35UVC275GS is defined by a comprehensive set of electrical, optical, and thermal parameters measured under standard conditions (Ta=25°C). Understanding these parameters is crucial for proper circuit design and thermal management to ensure reliability and achieve the desired radiant output.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. They are not intended for normal operation. The maximum power dissipation (Po) is 0.7 Watts, which is the total electrical power that can be converted into heat and light without damaging the LED. The maximum continuous forward current (IF) is 100 milliamperes (mA). The device is rated for an operating temperature range (Topr) of -40°C to +80°C and a storage temperature range (Tstg) of -40°C to +100°C. The maximum allowable junction temperature (Tj) is 90°C. Exceeding the junction temperature is a primary cause of LED failure and accelerated lumen depreciation.

2.2 Electro-Optical Characteristics

These are the typical performance parameters under specified test conditions. The forward voltage (VF) ranges from a minimum of 5.0V to a maximum of 7.0V at a test current of 60mA, with a typical value of 5.5V. This relatively high voltage is characteristic of UVC LEDs due to their wide bandgap semiconductor material. The radiant flux (Φe), which is the total optical power output in the UVC spectrum, is typically 10.0 milliwatts (mW) at 60mA. At a lower current of 20mA, it drops to 3.5 mW, and at the maximum current of 100mA, it reaches 14.0 mW. The peak wavelength (Wp) is centered at 275nm with a range from 265nm to 280nm, placing it firmly in the most effective germicidal range (approx. 260nm-280nm). The viewing angle (2θ1/2) is a wide 120 degrees, providing broad irradiation. The thermal resistance from the junction to the solder point (Rth j-s) is typically 38 K/W, indicating how effectively heat is transferred from the semiconductor chip to the board. A lower value is better for thermal management.

3. Bin Code System Explanation

To account for manufacturing variations, LEDs are sorted into performance bins. This allows designers to select components that meet the specific needs of their application. The LTPL-G35UVC275GS uses a three-dimensional binning system.

3.1 Forward Voltage (VF) Binning

LEDs are categorized into four voltage bins: V1 (5.0V - 5.5V), V2 (5.5V - 6.0V), V3 (6.0V - 6.5V), and V4 (6.5V - 7.0V), all measured at IF=60mA. Selecting LEDs from the same voltage bin ensures consistent current distribution when multiple devices are driven in parallel.

3.2 Radiant Flux (Φe) Binning

Optical output is binned into four categories: X1 (7.0 - 8.0 mW), X2 (8.0 - 9.0 mW), X3 (9.0 - 10.0 mW), and X4 (10.0 mW and above), measured at IF=60mA. This allows for predictable disinfection performance and dose calculation.

3.3 Peak Wavelength (Wp) Binning

All devices fall within a single wavelength bin, W1, which spans from 265nm to 280nm. The tight control around 275nm ensures optimal germicidal efficacy, as the effectiveness of UV light for disrupting DNA/RNA peaks in this region.

4. Performance Curve Analysis

The datasheet provides several graphs that illustrate the device's behavior under varying conditions. These curves are essential for dynamic modeling and understanding performance trade-offs.

4.1 Relative Spectral Distribution

This curve shows the intensity of light emitted across the ultraviolet spectrum. It confirms the narrow emission band centered at the peak wavelength, with minimal emission outside the UVC range, which is important for safety and efficacy.

4.2 Radiation Pattern

The radiation characteristic plot (often a polar diagram) visualizes the 120-degree viewing angle, showing how optical intensity decreases from the center (0 degrees) to the edges (±60 degrees). This informs optical design for achieving uniform irradiation.

4.3 Relative Radiant Flux vs. Forward Current

This graph demonstrates that radiant output increases with drive current but not linearly. It tends to saturate at higher currents due to increased heat and efficiency droop. This highlights the importance of driving the LED at an optimal current for the best balance of output and longevity.

4.4 Forward Voltage vs. Forward Current

The IV curve shows the exponential relationship between voltage and current, typical of a diode. It is used to determine the operating point when designing the current-limiting circuitry.

4.5 Temperature Dependence Curves

Graphs showing relative radiant flux and forward voltage as functions of junction temperature are critical. UVC LED output typically decreases as temperature increases. The forward voltage decreases with rising temperature. These relationships must be considered for designs operating in non-ambient conditions or with inadequate heat sinking.

4.6 Forward Current Derating Curve

This is one of the most important graphs for reliability. It shows 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 90°C limit. This curve is mandatory for determining heat sink requirements.

5. Mechanical and Package Information

The LED comes in a surface-mount device (SMD) package with dimensions of approximately 3.5mm x 3.5mm. The outline drawing provides precise measurements for footprint design. The package includes clear polarity markings (typically a cathode indicator) to prevent incorrect placement during assembly. The recommended printed circuit board (PCB) attachment pad layout is provided to ensure proper soldering and thermal connection. The pad design is crucial for transferring heat from the LED's thermal pad (solder point) to the PCB's copper layers, which act as a primary heat spreader.

6. Soldering and Assembly Guidelines

Proper handling and soldering are vital for maintaining LED performance and reliability.

6.1 Reflow Soldering Profile

A lead-free reflow profile is recommended. Key parameters include a preheat stage (150-200°C for 60-120s), a time above liquidus (217°C) of 60-150 seconds, and a peak temperature of 260°C (with 245°C recommended) held for 10-30 seconds. The ramp-up and cool-down rates should be controlled to a maximum of 3°C/s and 6°C/s, respectively, to minimize thermal shock. A rapid cooldown process is not advised.

6.2 Cleaning and Handling

If cleaning is necessary after soldering, only alcohol-based solvents like isopropyl alcohol should be used. Unspecified chemical cleaners can damage the silicone lens or package material. The LEDs are sensitive to electrostatic discharge (ESD), with a maximum withstand voltage of 2000V (Human Body Model). Standard ESD precautions should be observed during handling.

7. Packaging and Ordering Information

The LEDs are supplied on tape and reel for automated pick-and-place assembly. The tape dimensions and reel specifications (7-inch reel holding up to 500 pieces) conform to the EIA-481-1-B standard. The bin classification code is marked on each packing bag, allowing traceability of the electrical and optical characteristics of the batch.

8. Application Suggestions and Design Considerations

8.1 Typical Application Scenarios

The primary application is in germicidal devices: surface disinfectors for phones or small objects, water sterilization units for point-of-use systems, air purification modules in HVAC systems or portable air cleaners, and sterilization chambers for medical or dental tools. Its small size enables integration into compact and portable products.

8.2 Critical Design Considerations

Drive Circuitry: A constant current driver is essential, not a constant voltage source, to ensure stable optical output and prevent thermal runaway. The driver must be capable of supplying the required voltage (≥ VF max) at the set current.
Thermal Management: This is the most critical aspect of UVC LED system design. The high thermal resistance (38 K/W) means heat builds up quickly at the junction. A metal-core PCB (MCPCB) or other effective thermal management solution is mandatory to keep the junction temperature below 90°C, especially when operating at or near the maximum current. The derating curve must be followed.
Optical Design: The wide 120-degree beam may require reflectors or lenses to direct the UVC light onto the target surface for efficient disinfection. Materials must be UVC-stable (e.g., certain grades of aluminum, PTFE, quartz) as many plastics degrade under UVC exposure.
Safety: UVC radiation is harmful to human skin and eyes. Products must incorporate safety interlocks, timers, and shielding to prevent user exposure. Proper labeling is required.

9. Reliability and Lifetime

The datasheet includes a comprehensive reliability test plan. Tests such as Room Temperature Operating Life (RTOL), High/Low Temperature Operating Life (HTOL/LTOL), and temperature cycling are performed for up to 3000 hours. The criteria for failure are defined as a shift in forward voltage exceeding 10%, a drop in radiant flux below 50% of initial value, or a peak wavelength shift beyond ±2nm. These tests validate the product's robustness under various environmental stresses, supporting claims of long operational life when used within specifications.

10. Technical Comparison and Differentiation

Compared to traditional mercury-based UVC lamps, this LED offers significant advantages: instant start-up (no warm-up time), no hazardous mercury content, longer lifetime, compact size, and digital dimmability. Compared to other UVC LEDs, its specific combination of optical power (10mW typ @60mA), wavelength (275nm), and package size (3.5x3.5mm) positions it for applications requiring a balance of output and form factor. The detailed binning system provides predictability for high-volume manufacturing.

11. Frequently Asked Questions (Based on Technical Parameters)

Q: What driver voltage do I need?
A: Your constant current driver's output voltage compliance must be higher than the maximum forward voltage (VF max) of the LED bin you are using, typically 7.0V, plus some headroom for losses in traces and connections.
Q: How do I calculate the disinfection dose?
A: Dose (in Joules per square centimeter, J/cm²) is the product of irradiance (optical power per unit area, W/cm²) and exposure time (seconds). You must measure or calculate the irradiance at the target surface based on the LED's radiant flux, beam angle, distance, and optics. Compare this to the dose required to inactivate your target pathogen.
Q: Can I drive it at 100mA continuously?
A: You can only drive it at 100mA if you can guarantee the junction temperature remains below 90°C, which requires exceptional thermal management. Refer to the current derating curve; at elevated ambient temperatures, the maximum allowable current is significantly lower.
Q: Why is the forward voltage so high?
A> UVC LEDs are based on aluminum gallium nitride (AlGaN) semiconductors with a very wide bandgap, which inherently requires a higher voltage to excite electrons across the gap and produce short-wavelength photons.

12. Design and Usage Case Study

Case: Designing a Portable Water Sterilizer Bottle. A designer aims to create a bottle that can sterilize 500ml of water in 60 seconds. Using the LTPL-G35UVC275GS (X3 bin, 9-10mW), they plan to use 4 LEDs. The total radiant flux is ~36-40mW. The water is circulated past the LEDs in a thin chamber. Assuming 50% optical coupling efficiency and a required UV dose for common bacteria of 40 mJ/cm², they calculate the required chamber surface area and flow rate. A constant current driver set to 60mA per LED with a 9V output capability is selected. A small aluminum heat sink is integrated with the LED MCPCB to manage heat during the one-minute cycle, keeping the junction temperature well within limits. Safety features include a lid-interlock switch and an opaque outer shell.

13. Operating Principle Introduction

A UVC LED is a semiconductor p-n junction diode. When a forward voltage is applied, electrons are injected across the junction and recombine with holes in the active region. In a UVC LED, the energy bandgap of the semiconductor material (AlGaN) is very large (~4.5 electron volts). When recombination occurs, this energy is released in the form of a photon (light particle). The wavelength of this photon is inversely proportional to the bandgap energy (λ = hc/Eg). A bandgap of ~4.5 eV corresponds to a photon wavelength of approximately 275 nanometers, which is in the UVC range. This high-energy light is absorbed by the DNA and RNA of microorganisms, causing thymine dimers that prevent replication, thereby inactivating the pathogen.

14. Technology Trends and Developments

The field of UVC LEDs is rapidly evolving. Key trends include:
Increased Wall-Plug Efficiency (WPE): Research is focused on improving the internal quantum efficiency (how many electrons produce photons) and the light extraction efficiency (getting photons out of the chip), which directly increases radiant flux for a given electrical input, reducing system power and thermal load.
Longer Wavelengths >280nm: While ~275nm is optimal for germicidal action, LEDs emitting at slightly longer wavelengths (e.g., 280-285nm) can offer higher output power and efficiency while still maintaining significant disinfection capability, creating trade-off options for designers.
Improved Lifetime and Reliability: Advancements in chip design, packaging materials (especially UVC-stable encapsulants), and thermal management are steadily increasing the operational lifetime (L70, time to 70% of initial output) of UVC LEDs, making them more viable for continuous-operation applications.
Reduced Cost: As manufacturing volumes increase and yields improve, the cost per milliwatt of UVC optical power is decreasing, accelerating the adoption of LED technology across more market segments, from professional to consumer products.