LTPL-W35UV275GH UVC LED Datasheet - 35x35mm Package - 6.7V Typ - 275nm Peak Wavelength - 5.3W Max Power - English Technical Document

1. Product Overview

The LTPL-W35UV275GH is a high-performance, energy-efficient 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 long-lasting alternative to conventional UV light sources such as mercury lamps. By leveraging the inherent benefits of LED technology, including extended operational lifetime, instant on/off capability, and design flexibility, it enables new possibilities in disinfection system design.

Key features 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 attributes contribute to lower overall operating and maintenance costs for end-users, making it an economically viable solution for continuous or intermittent sterilization processes.

2. Technical Parameter Deep-Dive

2.1 Absolute Maximum Ratings

The device is specified for operation under the following absolute maximum conditions at an ambient temperature (Ta) of 25°C. Exceeding these ratings may cause permanent damage.

• Power Dissipation (Po): 5.3 Watts maximum.
• DC Forward Current (IF): 700 milliamperes maximum.
• Operating Temperature Range (Topr): -40°C to +80°C.
• Storage Temperature Range (Tstg): -40°C to +100°C.
• Junction Temperature (Tj): 110°C maximum.

It is critically important to avoid operating the LED under reverse bias conditions for extended periods, as this can lead to component failure.

2.2 Electro-Optical Characteristics

Measured at Ta=25°C, the key performance parameters define the LED's operational behavior.

• Forward Voltage (VF): Typically 6.7V at IF=600mA, with a range from 6.0V (Min) to 7.5V (Max). Measurement tolerance is ±0.1V.
• Radiant Flux (Φe): The total optical power output. At IF=700mA, the typical value is 165mW. At the recommended operating current of 600mA, the typical value is 150mW, with a minimum of 120mW. Measurement tolerance is ±10%.
• Peak Wavelength (Wp): Centered in the UVC spectrum. At IF=600mA, the wavelength ranges from 265nm (Min) to 280nm (Max), with a typical target of 275nm. Measurement tolerance is ±3nm.
• Thermal Resistance (Rth j-s): The thermal resistance from the semiconductor junction to the solder point is typically 10.5 K/W when measured at IF=600mA on a specified metal-core PCB and heatsink.
• Viewing Angle (2θ1/2): A wide 160-degree typical viewing angle, providing broad radiation coverage.
• Electrostatic Discharge (ESD): Withstands up to 2000V per the JESD22-A114-B standard, indicating good handling robustness.

3. Bin Code System

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

3.1 Forward Voltage (VF) Binning

• V1: 6.0V to 6.5V @ 600mA
• V2: 6.5V to 7.0V @ 600mA
• V3: 7.0V to 7.5V @ 600mA

Tolerance per bin is ±0.1V.

3.2 Radiant Flux (Φe) Binning

• X2: 120mW to 140mW @ 600mA
• X3: 140mW to 160mW @ 600mA
• X4: 160mW and above @ 600mA

Tolerance per bin is ±7%.

3.3 Peak Wavelength (Wp) Binning

• W1: 265nm to 280nm @ 600mA

Tolerance per bin is ±3nm.

4. Performance Curve Analysis

The datasheet includes several characteristic curves crucial for design engineers.

4.1 Relative Spectral Distribution

This graph shows the intensity of light emitted across different wavelengths, confirming the narrowband UVC output centered around 275nm, which is highly effective for germicidal action.

4.2 Radiation Pattern

The polar diagram illustrates the spatial distribution of radiant intensity, showing the wide 160-degree emission profile.

4.3 Relative Radiant Flux vs. Forward Current

This curve demonstrates the relationship between drive current and light output. The radiant flux increases with current but will eventually saturate. Operating at or below the recommended 600mA ensures optimal efficiency and longevity.

4.4 Forward Voltage vs. Forward Current

The IV curve shows the exponential relationship typical of diodes. The forward voltage increases with current, which is important for designing the constant-current driver circuitry.

4.5 Thermal Characteristics

Two key graphs show the impact of temperature:
1. Relative Radiant Flux vs. Junction Temperature: UVC LED output is sensitive to temperature. This curve shows the depreciation of optical power as the junction temperature rises, highlighting the critical need for effective thermal management.
2. Forward Voltage vs. Junction Temperature: Shows how the forward voltage decreases with increasing junction temperature, which can be used for indirect temperature monitoring.

4.6 Forward Current Derating Curve

This graph defines the maximum allowable forward current as a function of the ambient or case temperature. To prevent exceeding the maximum junction temperature, the drive current must be reduced when operating in higher temperature environments.

5. Mechanical and Package Information

5.1 Outline Dimensions

The LED package has a footprint of approximately 35mm x 35mm. All critical dimensions, including lens height and pad locations, are provided in the detailed mechanical drawing with a general tolerance of ±0.2mm unless otherwise specified.

5.2 Recommended PCB Attachment Pad

A detailed land pattern design is provided for the surface-mount pads. Adherence to this specification, with a tolerance of ±0.1mm, is essential for proper soldering, alignment, and thermal performance. The design ensures sufficient solder fillets and thermal relief for the high-power dissipation.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

Low-temperature surface-mount technology (SMT) is strongly recommended. A specific reflow profile is provided:
- Pre-heat Rate: 1-3°C/sec.
- Soak Temperature: 110-140°C for 60-100 seconds.
- Reflow: Above 140°C for 30-60 seconds.
- Peak Temperature: Must NOT exceed 170°C, and the time above this temperature should be a maximum of 10 seconds.

It is critical to use a Bi-based solder paste with a melting temperature below 140°C. The package should only undergo the reflow process once. The use of a soldering iron or hot plate is prohibited.

6.2 Cleaning

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

7. Packaging and Handling

7.1 Tape and Reel Specifications

The LEDs are supplied in embossed carrier tape sealed with a cover tape, wound onto 7-inch reels. Standard reel capacity is up to 500 pieces, with a minimum order quantity of 100 pieces for partial reels. The packaging conforms to EIA-481-1-B standards. A maximum of two consecutive empty pockets is allowed.

8. Reliability and Testing

A comprehensive reliability test plan validates the long-term performance of the LED under various stress conditions.

8.1 Reliability Test Conditions

Tests include Room Temperature Operating Life (RTOL) at multiple currents (350mA, 600mA, 700mA), High/Low Temperature Operating Life (HTOL/LTOL), damp heat tests (WHTOL), storage tests (HTS, LTS, WHTS), and Thermal Shock (TS). All operating life tests are conducted with the LED mounted on a specified metal heatsink to ensure realistic thermal conditions.

8.2 Failure Criteria

A device is considered a failure if, after testing, its parameters shift beyond defined limits:
- Forward Voltage (VF): Increase of more than 10% from initial.
- Radiant Flux (Φe): Decrease to less than 50% of initial.
- Peak Wavelength (Wp): Shift beyond ±2nm from initial.

9. Application Notes and Design Considerations

9.1 Drive Method

UVC LEDs must be driven by a constant current source, not a constant voltage source. The driver should be capable of supplying the required current (e.g., 600mA) while accommodating the forward voltage range of the selected bin. Proper current regulation is essential for stable optical output and long life.

9.2 Thermal Management

This is the single most critical aspect of designing with high-power UVC LEDs. The typical thermal resistance of 10.5 K/W means that at 5.3W dissipation, the junction will be about 56°C hotter than the solder point. An appropriately sized metal-core PCB (MCPCB) and an external heatsink are mandatory to keep the junction temperature well below the 110°C maximum, preferably below 80°C for optimal lifetime and output stability. The derating curve must be followed.

9.3 Optical and Safety Considerations

UVC radiation is harmful to human skin and eyes. Any product incorporating this LED must include adequate shielding and safety interlocks to prevent exposure. The materials used in the fixture (e.g., lenses, reflectors, housing) must be resistant to UVC degradation, as many plastics and adhesives yellow or crack under prolonged exposure.

10. Technical Comparison and Advantages

Compared to traditional mercury-based UVC lamps, this solid-state LED solution offers several distinct advantages:
- Instant On/Off: No warm-up or cool-down time, enabling pulsed operation for energy savings.
- Long Lifetime: LEDs typically maintain useful output for thousands of hours, reducing replacement frequency.
- Design Flexibility: Small size and directional output allow for compact and targeted disinfection systems.
- Environmental Safety: Contains no mercury, aligning with global environmental regulations.
- Durability: More resistant to physical shock and vibration than glass lamps.

11. Frequently Asked Questions (FAQ)

Q: What is the typical lifetime of this LED?
A: While the datasheet provides reliability test data (e.g., 1000-3000 hour tests), the actual operational lifetime (L70 - time to 70% of initial flux) depends heavily on drive current and thermal management. Under recommended conditions (600mA, Tj < 80°C), lifetimes exceeding 10,000 hours can be expected.

Q: Can I drive this LED with a 12V power supply?
A: No. You must use a constant-current driver matched to the LED's voltage requirement (~6.7V typical). A simple 12V supply would destroy the LED due to excessive current.

Q: How do I select the right bin for my application?
A: For maximum germicidal efficacy, select a bin with a peak wavelength closest to 265nm (within the W1 range). For consistent system performance, specify both VF and flux bins (e.g., V2, X3) to ensure uniform electrical and optical characteristics across multiple units.

Q: Is a lens required?
A> The LED has a primary lens. A secondary optical system (reflector or additional lens) may be used to further collimate or shape the beam for specific application needs, but it must be UVC-resistant.

12. Operating Principle and Trends

12.1 Operating Principle

UVC LEDs generate light through electroluminescence in a semiconductor material (typically aluminum gallium nitride - AlGaN). When a forward voltage is applied, electrons and holes recombine in the active region, releasing energy in the form of photons. The specific bandgap of the AlGaN material determines the photon energy, corresponding to the UVC wavelength (~275nm). This short-wavelength, high-energy light is absorbed by the DNA and RNA of microorganisms, disrupting their replication and rendering them inactive.

12.2 Industry Trends

The UVC LED market is focused on increasing wall-plug efficiency (optical power out / electrical power in), which directly impacts system size and cost. Trends include developing epitaxial structures with higher internal quantum efficiency, improving light extraction from the chip, and enhancing package designs for lower thermal resistance. As efficiency improves and costs decrease, UVC LEDs are expanding from niche applications into broader markets like water and surface disinfection in consumer, commercial, and industrial settings.