UVC LED LTPL-G35UV275PB Datasheet - 3.5x3.5x1.05mm - 6.0V Typ - 275nm Peak - 16mW Typ - English Technical Document

1. Product Overview

The LTPL-G35UV product series represents a revolutionary and energy-efficient light source specifically engineered for sterilization and medical applications. This technology merges the long lifetime and high reliability inherent to Light Emitting Diodes (LEDs) with performance characteristics suitable for displacing conventional ultraviolet light sources. It offers significant design freedom, enabling new opportunities for solid-state UVC solutions in demanding environments.

Key features of this product include its compatibility with integrated circuits (I.C. compatible), compliance with RoHS environmental standards (lead-free), and the potential for lower operational and reduced maintenance costs compared to traditional UV technologies like mercury lamps.

1.1 Core Advantages and Target Market

The primary advantage of this UVC LED is its solid-state nature, which translates to instant on/off capability, no warm-up time, and no hazardous materials like mercury. The target market is focused on applications requiring precise, reliable, and safe ultraviolet irradiation. This includes but is not limited to: surface disinfection systems for medical equipment, air and water purification devices, and analytical instrumentation within life sciences and healthcare. The product is designed for engineers and system integrators developing next-generation sterilization solutions that demand compact form factors, digital controllability, and enhanced safety.

2. Outline and Mechanical Dimensions

The LED package has a compact surface-mount design. All critical dimensions are provided in millimeters with a standard tolerance of ±0.2mm unless otherwise specified. The physical outline is crucial for PCB layout and thermal management design, ensuring proper alignment, soldering, and heat dissipation from the junction to the solder points and the printed circuit board.

3. Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed and should be avoided for reliable performance.

• Power Dissipation (P_O): 1.05 W
• DC Forward Current (I_F): 150 mA
• Operating Temperature Range (T_opr): -40°C to +80°C
• Storage Temperature Range (T_stg): -40°C to +100°C
• Junction Temperature (T_j): 115°C

Important Note: Extended operation of the LED under reverse bias conditions can lead to component damage or failure. Proper circuit protection (e.g., a series diode or TVS) is recommended in applications where reverse voltage is a possibility.

4. Electro-Optical Characteristics

These parameters are measured at an ambient temperature (T_a) of 25°C and define the typical performance of the device under specified test conditions.

Measurement Notes:
1. Radiant flux is the total optical power output measured with an integrating sphere.
2. Forward voltage measurement tolerance is ±0.1V.
3. Peak wavelength measurement tolerance is ±3nm.
4. Radiant flux measurement tolerance is ±10%.
5. The thermal resistance value is referenced using a 2.0cm x 2.0cm x 0.17cm aluminum Metal Core PCB (MCPCB).

5. Bin Code and Classification System

The LEDs are sorted into performance bins to ensure consistency. The bin code is marked on each packing bag.

5.1 Forward Voltage (V_F) Binning

Tolerance on each bin is ±0.1V.

5.2 Radiant Flux (Φ_e) Binning

Tolerance on each bin is ±10%.

5.3 Peak Wavelength (λ_P) Binning

Tolerance on each bin is ±3nm.

6. Typical Performance Curves and Analysis

The following curves provide insight into the device's behavior under varying electrical and thermal conditions (measured at 25°C ambient unless noted).

6.1 Relative Spectral Distribution

This curve shows the emission spectrum, centered around the peak wavelength (e.g., 275nm). It is typically narrow for LEDs, which is beneficial for targeting specific photochemical reactions in sterilization without emitting unnecessary or harmful wavelengths.

6.2 Radiation Pattern (Viewing Angle)

The radiation characteristic plot illustrates the angular distribution of light intensity. The typical 120° viewing angle (2θ_1/2) indicates a Lambertian or wide-beam pattern, which is useful for evenly illuminating surfaces in close proximity.

6.3 Relative Radiant Flux vs. Forward Current

This graph demonstrates the relationship between drive current and optical output. Radiant flux generally increases with current but will exhibit sub-linear growth at higher currents due to efficiency droop and increased junction temperature. The curve is essential for determining the optimal operating point for balancing output and longevity.

6.4 Forward Voltage vs. Forward Current

The I-V curve shows the exponential relationship typical of a diode. The forward voltage increases with current. Understanding this curve is vital for designing the appropriate constant current driver to ensure stable operation.

6.5 Relative Radiant Flux vs. Junction Temperature

This is a critical curve for thermal management. UVC LED efficiency decreases as junction temperature rises. The plot quantifies this derating, emphasizing the importance of effective heat sinking to maintain high output and long device life.

6.6 Forward Voltage vs. Junction Temperature

The forward voltage typically has a negative temperature coefficient (decreases with increasing temperature). This characteristic can sometimes be used for indirect temperature monitoring.

6.7 Forward Current Derating Curve

This curve defines the maximum allowable forward current as a function of the ambient or case temperature. To prevent exceeding the maximum junction temperature (115°C), the drive current must be reduced when operating at higher ambient temperatures. Adherence to this curve is mandatory for reliable operation.

7. Reliability Testing and Criteria

A comprehensive reliability test plan validates the long-term performance and robustness of the LED.

7.1 Test Conditions

Note: Operating life tests are conducted with the LED mounted on a 90x70x4mm aluminum heat sink.

7.2 Failure Criteria

After testing, devices are judged against the following criteria:
- Forward Voltage (V_F): Change must not exceed +10% of the initial value when measured at I_F = 100mA.
- Radiant Flux (Φ_e): Output must not fall below 50% of the initial value when measured at I_F = 100mA.

8. Assembly and Handling Guidelines

8.1 Recommended Reflow Soldering Profile

For lead-free assembly, the following profile is suggested to prevent thermal damage to the LED package:

• Average Ramp-Up Rate (T_L to T_P): Max 3°C/second
• Preheat: 150°C to 200°C for 60-120 seconds (t_S)
• Time Above Liquidus (T_L=217°C): 60-150 seconds (t_L)
• Peak Temperature (T_P): 260°C maximum (245°C recommended)
• Time within 5°C of Peak (t_P): 10-30 seconds
• Ramp-Down Rate: Max 6°C/second
• Total Time (25°C to Peak): Max 8 minutes

8.2 PCB Pad Layout Recommendation

A recommended footprint for the surface-mount pads is provided to ensure proper solder joint formation and mechanical stability. The tolerance for this pad specification is ±0.1mm.

8.3 Packaging: Tape and Reel Specifications

The LEDs are supplied in embossed carrier tape and reel packaging for automated assembly.
- Reel size: 7 inches.
- Maximum quantity per reel: 500 pieces (minimum packing for remainders is 100 pieces).
- The packaging conforms to EIA-481-1-B specifications.
- Empty pockets are sealed with cover tape.
- A maximum of two consecutive missing components is allowed.

9. Important Cautions and Application Notes

9.1 Cleaning

If cleaning is necessary after soldering, use only alcohol-based solvents such as isopropyl alcohol. Unspecified chemical cleaners may damage the LED package material (e.g., lens or encapsulant) and degrade performance or reliability.

9.2 Drive Method and General Precautions

LEDs are current-driven devices. They must be operated using a constant current source, not a constant voltage source, to ensure stable light output and prevent thermal runaway. The driver circuit should be designed to limit inrush current and provide protection against electrical transients (ESD, surges).

Additional Soldering Notes:
1. Hand soldering is possible with an iron tip temperature maximum of 300°C for a maximum duration of 2 seconds, only once per pad.
2. Reflow soldering should be performed a maximum of three times.
3. All temperature specifications refer to the top side of the package.
4. A rapid cooling process from peak temperature is not recommended.
5. The lowest possible soldering temperature that achieves a reliable joint is always desirable.
6. Dip soldering is not a recommended or guaranteed assembly method for this component.

10. Technical Deep Dive and Design Considerations

10.1 Thermal Management Imperative

The thermal resistance from junction to solder point (R_{th j-s}) is 30 K/W typical. Effective heat sinking is non-negotiable for UVC LEDs. The high photon energy of UVC generation results in significant heat at the semiconductor junction. Without proper dissipation, the junction temperature will rise, leading to accelerated lumen depreciation, wavelength shift, and ultimately, catastrophic failure. Designers must use appropriate MCPCBs or other thermal management strategies to keep T_j well below the 115°C maximum, ideally at 80°C or lower for maximum lifetime.

10.2 Optical Design for Sterilization Efficacy

The 275nm peak wavelength is within the germicidal effectiveness range (approx. 260nm-280nm), where DNA/RNA absorption is high. The radiant flux (mW), not luminous flux (lm), is the relevant metric. System design must ensure the target surface receives the required UV dose (measured in J/m² or mJ/cm²), which is a product of irradiance (W/m²) and exposure time. The wide 120° viewing angle helps with uniform coverage but reduces peak irradiance at a given distance. For focused applications, secondary optics may be required.

10.3 Electrical Interface and Driver Selection

With a typical forward voltage of 6.0V at 100mA, the LED requires a driver capable of delivering a stable constant current up to 150mA with a compliance voltage above 7.0V. Given the negative temperature coefficient of V_F, a simple resistive current limit is inadequate and dangerous, as it can lead to thermal runaway. A dedicated LED driver IC or a properly designed linear/switch-mode constant current circuit is essential. The driver should also include features for soft-start and over-voltage protection.

10.4 Material Compatibility and Safety

UVC radiation at 275nm is highly energetic and can degrade many organic materials, including plastics, adhesives, and wire insulation used in the assembly. All materials in the optical path and near the LED must be rated for UVC exposure. Furthermore, UVC is harmful to human skin and eyes. Any end-product must incorporate adequate shielding, interlock systems, and warning labels to ensure user safety, complying with relevant laser product or light safety standards (e.g., IEC 62471).

11. Comparison with Conventional UV Technologies

The LTPL-G35UV275PB offers distinct advantages over traditional UV sources like low-pressure mercury lamps:
Advantages:
- Instant On/Off: No warm-up or cool-down time, enabling pulsed operation.
- Compact & Robust: Solid-state, no fragile glass tubes or filaments.
- Mercury-Free: Environmentally friendly and avoids hazardous material disposal issues.
- Wavelength Specificity: Narrow emission spectrum targets germicidal effectiveness without extraneous UV-A/UV-B.
- Digital Control: Easily dimmable and integrable with smart control systems.
Considerations:
- Higher Initial Cost per mW: Although total cost of ownership may be lower.
- Thermal Management: Requires more active thermal design than some conventional lamps.
- Optical System: May require different optics design due to the smaller emitting area and different radiation pattern.

12. Application Scenarios and Use Cases

• Surface Disinfection: Integration into devices for disinfecting medical tools, smartphone screens, or frequently touched surfaces in hospitals and public spaces.
• Water Purification: Used in point-of-use or inline water purifiers to inactivate bacteria and viruses without chemicals.
• Air Sterilization: Embedded in HVAC systems or portable air purifiers to treat circulating air.
• Life Sciences Equipment: Providing UV illumination in PCR workstations, biosafety cabinets, or crosslinkers.
• Consumer Products: Compact sterilizers for personal items like toothbrushes, baby bottles, or masks (with appropriate safety enclosures).

13. Frequently Asked Questions (FAQ)

Q: What is the expected lifetime of this UVC LED?
A: Lifetime is typically defined as the operating hours until the radiant flux depreciates to 50% (L50). This is heavily dependent on drive current and junction temperature. Operating at the typical 100mA with good thermal management (low T_j) can yield lifetimes exceeding 10,000 hours, far surpassing many conventional UV sources.

Q: Can I drive this LED with a 5V power supply?
A: No. The typical forward voltage is 6.0V, and the maximum can be 7.0V. A 5V supply would not turn the LED on sufficiently. A boost converter or a driver with a higher output compliance voltage is required.

Q: How do I interpret the bin codes when ordering?
A> Specify the required V_F bin (V1-V4), Φ_e bin (X1-X3), and λ_P bin (W1) based on your application's needs for voltage consistency, output power, and precise wavelength. This ensures you receive LEDs with tightly grouped characteristics.

Q: Is the light output visible?
A: No. UVC radiation at 275nm is outside the visible spectrum (400-700nm). The LED may have a very faint blue/violet glow due to minor secondary emissions, but the primary germicidal output is invisible. This invisibility makes safety interlocks even more critical.