UVC LED LTPL-G35UV275UZ Datasheet - 3.5mm x 3.5mm Package - 5.0-7.5V Forward Voltage - 72mW Radiant Flux - 275nm Peak Wavelength - English Technical Document

1. Product Overview

The LTPL-G35UV275UZ is a high-power UVC light-emitting diode designed for sterilization and medical applications. It represents a solid-state lighting solution that aims to replace conventional UV light sources by offering superior energy efficiency, longer operational lifetime, and enhanced reliability. The device emits ultraviolet-C radiation with a peak wavelength centered around 275 nanometers, which is highly effective for germicidal purposes.

Key advantages of this LED include its compatibility with integrated circuits, compliance with RoHS environmental standards, and its lead-free construction. From an operational standpoint, it promises lower running costs and reduced maintenance requirements compared to traditional mercury-based UV lamps, providing designers with greater freedom in system integration.

1.1 Core Features and Target Market

The primary application for this component is in devices requiring disinfection, such as water purification systems, air sterilizers, and surface sanitization equipment in medical, laboratory, and consumer settings. Its design enables compact form factors and precise control of UV dosage, which are critical factors in effective sterilization protocols.

2. Technical Specifications and In-Depth Interpretation

2.1 Absolute Maximum Ratings

Operating the device beyond these limits may cause permanent damage. The absolute maximum ratings are specified at an ambient temperature (Ta) of 25°C.

• Power Dissipation (P_O): 3.8 W. This is the maximum total power the package can dissipate as heat.
• DC Forward Current (I_F): 500 mA. The maximum continuous forward current that can be applied.
• Operating Temperature Range (T_opr): -40°C to +80°C. The ambient temperature range for normal operation.
• Storage Temperature Range (T_stg): -40°C to +100°C. The temperature range for non-operational storage.
• Junction Temperature (T_j): 115°C. The maximum allowable temperature at the semiconductor junction.

Important Note: Prolonged operation under reverse bias conditions can lead to component failure. Proper circuit protection is essential.

2.2 Electro-Optical Characteristics

These parameters are measured at Ta=25°C and define the device's performance under typical operating conditions.

• Forward Voltage (V_F): Typically 6.0V, with a range from 5.0V (Min.) to 7.5V (Max.) at a drive current (I_F) of 350mA. The measurement tolerance is ±0.1V. This relatively high forward voltage is characteristic of UVC LEDs.
• Radiant Flux (Φ_e): The total optical power output. At I_F=350mA, the typical value is 72.0 mW, with a minimum of 56.0 mW. At the maximum rated current of 500mA, the typical radiant flux increases to 102.0 mW. Measurement tolerance is ±10%.
• Peak Wavelength (W_P): Ranges from 270 nm to 280 nm at I_F=350mA, with a typical target of 275nm. Tolerance is ±3nm. This wavelength is within the most effective band for disrupting microbial DNA/RNA.
• Thermal Resistance (R_{th j-s}): Typically 12.3 K/W from the junction to the solder point. This value is critical for thermal management design and is measured using a specific aluminum MCPCB as a reference.
• Viewing Angle (2θ_1/2): Typically 120 degrees, providing a wide radiation pattern.
• Electrostatic Discharge (ESD) Sensitivity: Withstands a minimum of 2000V per the JESD22-A114-B standard, indicating good handling robustness.

2.3 Thermal Characteristics and Management

Effective heat sinking is paramount for UVC LED performance and longevity. The thermal resistance of 12.3 K/W means that for every watt of power dissipated, the junction temperature will rise 12.3°C above the solder point temperature. To maintain the junction below its maximum of 115°C, especially when driving at 500mA, a high-quality metal-core PCB (MCPCB) or other effective thermal path is mandatory. The derating curve (Fig. 7) visually illustrates how the maximum allowable forward current decreases as the ambient temperature increases.

3. Bin Code System Explanation

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

3.1 Forward Voltage (V_F) Binning

LEDs are categorized into five bins (V0 to V4) based on their forward voltage at 350mA:

V0: 5.0V – 5.5V

V1: 5.5V – 6.0V

V2: 6.0V – 6.5V

V3: 6.5V – 7.0V

V4: 7.0V – 7.5V

Tolerance: ±0.1V per bin.

3.2 Radiant Flux (Φ_e) Binning

LEDs are sorted into four flux output bins (X1 to X4) at 350mA:

X1: 56 mW – 66 mW

X2: 66 mW – 76 mW

X3: 76 mW – 86 mW

X4: 86 mW and above

Tolerance: ±10% per bin.

3.3 Peak Wavelength (W_P) Binning

All devices fall into a single wavelength bin:

W1: 270 nm – 280 nm

Tolerance: ±3nm.

4. Performance Curve Analysis

The datasheet provides several key graphs for design engineers.

4.1 Relative Spectral Distribution (Fig. 1)

This curve shows the intensity of light emitted across the UV spectrum. It confirms the narrow emission band centered at 275nm, with minimal emission outside the germicidal range, ensuring efficient and targeted sterilization action.

4.2 Radiation Pattern (Fig. 2)

Illustrates the spatial distribution of radiant intensity, characterized by the 120-degree viewing angle. This helps in optical design for achieving uniform irradiation on a target surface.

4.3 Relative Radiant Flux vs. Forward Current (Fig. 3)

Shows that optical output increases with drive current but will eventually saturate. The curve is essential for determining the optimal drive current for balancing output power against efficiency and device lifetime.

4.4 Forward Voltage vs. Forward Current (Fig. 4)

Depicts the IV characteristic of the diode. The voltage increases logarithmically with current. This data is necessary for designing the current driver circuit.

4.5 Temperature Dependence (Fig. 5 & 6)

Fig. 5 (Relative Radiant Flux vs. Junction Temperature): Demonstrates the negative temperature coefficient of UVC LEDs. As junction temperature rises, optical output decreases significantly. This underscores the critical importance of thermal management to maintain stable output.

Fig. 6 (Forward Voltage vs. Junction Temperature): Shows that forward voltage decreases linearly with increasing junction temperature. This characteristic can sometimes be used for indirect temperature monitoring.

4.6 Forward Current Derating Curve (Fig. 7)

Perhaps the most critical graph for reliability. It defines the maximum allowable forward current as a function of the ambient temperature. To prevent overheating and ensure long life, the operating current must be reduced when the LED is used in higher temperature environments.

5. Mechanical and Package Information

5.1 Outline Dimensions

The device features a surface-mount package with dimensions of approximately 3.5mm x 3.5mm. All dimensional tolerances are ±0.2mm unless otherwise specified. The datasheet includes a detailed mechanical drawing showing the top, side, and bottom views, including the location of the cathode marking.

5.2 Recommended PCB Pad Design

A detailed land pattern diagram is provided to ensure reliable soldering and optimal thermal transfer from the LED's thermal pad to the PCB. Adherence to these recommended pad dimensions (with a tolerance of ±0.1mm) is crucial for mechanical stability and thermal performance.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A lead-free reflow profile is recommended:

- Peak Temperature (T_P): 260°C maximum (245°C recommended).

- Time above liquidus (T_L=217°C): 60-150 seconds.

- Time within 5°C of peak (t_P): 10-30 seconds.

- Maximum ramp-up rate: 3°C/sec.

- Maximum ramp-down rate: 6°C/sec.

- Total time from 25°C to peak: 8 minutes max.

Important Notes: Reflow soldering should be performed a maximum of three times. A rapid cooling process is not recommended. All temperature measurements refer to the top surface of the package.

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 a maximum of 2 seconds per solder joint. This operation should be performed only once.

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 material and optical properties.

7. Packaging and Handling

7.1 Tape and Reel Specifications

The LEDs are supplied on embossed carrier tape and reels compliant with EIA-481-1-B specifications.

- Reel Size: 7 inches.

- Quantity per Reel: Maximum 500 pieces (minimum 100 pieces for remainder lots).

- Tape pockets are sealed with a cover tape. The maximum number of consecutive missing components is two. Detailed dimensions for the tape pocket and the reel are provided in the datasheet.

8. Reliability and Lifetime

8.1 Reliability Test Plan

The device undergoes a comprehensive suite of reliability tests, each for 1,000 hours or 100 cycles:

1. Room Temperature Operating Life (RTOL) at 350mA.

2. Room Temperature Operating Life (RTOL) at 500mA.

3. High Temperature Storage Life (HTSL) at 100°C.

4. Low Temperature Storage Life (LTSL) at -40°C.

5. Damp Heat Storage (WHTSL) at 60°C/90% RH.

6. Thermal Shock (TS) from -30°C to +85°C.

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

8.2 Failure Criteria

A device is considered to have failed reliability testing if, after the test, either:

- The forward voltage (at 350mA) has increased by more than 10% from its initial value, or

- The radiant flux (at 350mA) has degraded to less than 50% of its initial value.

9. Application Notes and Design Considerations

9.1 Drive Method

A constant current driver is mandatory for operating this LED. The drive current should be selected based on the required radiant output, thermal design capabilities, and desired lifetime, using the derating curve as a guide. Pulsed driving can be considered to manage peak junction temperature in high-power applications.

9.2 Thermal Design

This is the single most critical aspect of system design. Use the provided thermal resistance value (12.3 K/W) to calculate the necessary heat sink performance. A high-thermal-conductivity MCPCB (like the referenced aluminum type) is strongly recommended. Ensure low thermal impedance from the LED's solder point to the ambient environment.

9.3 Optical and Safety Considerations

UVC radiation is harmful to human skin and eyes. The final product must incorporate appropriate shielding and safety interlocks to prevent user exposure. Materials used in the optical path (lenses, windows) must be UVC-transparent, such as fused silica or specific grades of quartz, as standard glass and plastics absorb UVC light.

10. Technical Comparison and Trends

10.1 Advantages Over Conventional UV Sources

Compared to mercury vapor lamps, this UVC LED offers:

- Instant On/Off: No warm-up or cool-down time.

- Compact Size: Enables miniaturization of equipment.

- Durability: More resistant to physical shock and vibration.

- Wavelength Specificity: Targeted 275nm output without broad-spectrum waste heat.

- Environmental Benefit: Contains no mercury.

10.2 Principle of Operation and Efficacy

UVC light at 275nm is absorbed by the DNA and RNA of microorganisms (bacteria, viruses, molds). This absorption causes the formation of thymine dimers, which disrupts the genetic code and prevents replication, effectively inactivating the pathogen. The efficacy varies by organism type, with required doses (fluence) specified in mJ/cm².

10.3 Market Trends

The UVC LED market is driven by increasing demand for mercury-free disinfection solutions across healthcare, water treatment, air purification, and consumer electronics. Key development trends include increasing wall-plug efficiency (optical power out / electrical power in), higher output power per chip, and longer operational lifetimes, all of which are improving the cost-effectiveness of LED-based systems.