ELUA2835TG0 UVA LED Datasheet - 2.8x3.5mm Package - 3.0-4.0V Forward Voltage - 150mA - 360-400nm Peak Wavelength - English Technical Document

1. Product Overview

The ELUA2835TG0 series represents a compact, high-performance ultraviolet-A (UVA) light-emitting diode designed for surface-mount technology (SMT) applications. This product is engineered to deliver high efficacy and reliable operation within a minimal footprint, making it suitable for integration into space-constrained designs.

1.1 Core Advantages and Target Market

The primary advantages of this LED include its low power consumption, wide viewing angle of 100 degrees, and a compact form factor measuring 2.8mm by 3.5mm. It incorporates built-in electrostatic discharge (ESD) protection rated up to 2KV, enhancing its robustness during handling and assembly. The device is fully compliant with RoHS, Pb-free, EU REACH, and halogen-free regulations (with Bromine <900ppm, Chlorine <900ppm, Br+Cl <1500ppm), making it suitable for global markets with stringent environmental requirements. Its target applications are primarily in the UVA spectrum, including UV nail curing, counterfeit detection systems, and insect trapping devices.

2. Technical Parameter Deep-Dive

This section provides an objective and detailed interpretation of the key technical parameters specified in the datasheet.

2.1 Absolute Maximum Ratings

The device is rated for a maximum continuous forward current (I_F) of 180mA, though it is typically operated at 150mA. The maximum junction temperature (T_J) is 90°C, which is a critical parameter for thermal management design. The thermal resistance from junction to ambient (R_th) is specified as 15°C/W. The operating and storage temperature range is from -40°C to +85°C, indicating suitability for harsh environments.

2.2 Photometric and Electrical Characteristics

The product nomenclature reveals detailed specifications. For example, a typical part number ELUA2835TG0-P6070SC53040150-VA1D(CM) indicates a peak wavelength in the 360-370nm range (P6070) with a minimum radiant flux of 210mW (SC3 bin), a typical value of 240mW, and a maximum of 270mW. Its forward voltage (V_F) is specified between 3.0V and 4.0V at 150mA. Another variant, ELUA2835TG0-P9000SC13040150-VA1D(CM), targets the 390-400nm wavelength with similar electrical characteristics but a slightly higher typical radiant flux of 250mW.

3. Binning System Explanation

The manufacturer employs a precise binning system to ensure consistency and allow for design flexibility.

3.1 Radiant Flux Binning

Radiant flux is categorized into bins such as SC3 (210-250mW), SC5 (250-270mW), SC7 (270-300mW), and SC9 (300-330mW). Measurements have a tolerance of ±10%. Designers can select bins based on the required optical output for their application.

3.2 Peak Wavelength Binning

The wavelength is tightly controlled. For the 365nm region, bins are W36A (360-365nm) and W36B (365-370nm). For the 395nm region, bins are W39A (390-395nm) and W39B (395-400nm). The measurement tolerance is ±1nm.

3.3 Forward Voltage Binning

Forward voltage is binned in 0.1V increments from 3.0V to 4.0V (e.g., 3031 for 3.0-3.1V, 3132 for 3.1-3.2V, etc.). This allows for better current matching when multiple LEDs are used in series. The measurement tolerance is ±2%.

4. Performance Curve Analysis

The datasheet provides several graphs characterizing performance under varying conditions. All curves are provided for both 365nm and 395nm variants at a substrate temperature of 25°C unless otherwise stated.

4.1 Forward Voltage vs. Forward Current (IV Curve)

The graph shows a non-linear relationship typical of diodes. The forward voltage increases with current. At the nominal 150mA, V_F is approximately 3.4V for the 365nm LED and slightly higher for the 395nm LED. This information is crucial for driver design.

4.2 Relative Radiant Flux vs. Forward Current

Output flux increases with current but shows signs of saturation at higher currents, particularly for the 395nm LED. Operating at 150mA appears to be within a efficient region before significant efficiency droop.

4.3 Relative Spectral Distribution

The graphs show narrow emission peaks centered around 365nm and 395nm, confirming the UVA emission. There is minimal visible light emission, which is desirable for pure UV applications.

4.4 Temperature Dependence

Key parameters are plotted against substrate temperature at a fixed 150mA current. The relative radiant flux decreases as temperature increases, with the 365nm LED showing a more pronounced thermal quenching effect. Forward voltage decreases linearly with increasing temperature. Peak wavelength shifts to longer wavelengths (red-shift) with increasing temperature.

4.5 Derating Curve

A critical graph shows the maximum allowable forward current as a function of substrate temperature. As temperature rises, the maximum safe current decreases linearly. This curve must be followed to ensure the junction temperature does not exceed 90°C and to maintain long-term reliability.

5. Mechanical and Packaging Information

5.1 Dimensional Drawing

The mechanical drawing specifies a package size of 2.8mm (length) by 3.5mm (width). The lens height is also defined. Tolerances are ±0.2mm unless otherwise noted. The drawing clearly identifies the anode and cathode pads. A critical note specifies that the thermal pad is electrically connected to the cathode. Designers must account for this in their PCB layout to avoid short circuits.

5.2 Handling and Polarity

A specific warning advises against handling the device by the lens, as mechanical stress can cause failure. The polarity is marked on the device itself and corresponds to the pad layout in the drawing.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Process

The LED is suitable for standard SMT reflow processes. The datasheet provides a generic reflow profile graph indicating temperature zones. Key recommendations include: avoiding more than two reflow cycles, minimizing mechanical stress on the LED during heating, and not bending the PCB after soldering. These steps are essential to prevent solder joint failure or damage to the internal die and wire bonds.

7. Packaging and Ordering Information

7.1 Emitter Tape and Reel

The LEDs are supplied on embossed carrier tape. The tape dimensions are provided in the datasheet. A standard reel contains 2000 pieces, which is typical for automated pick-and-place assembly lines.

7.2 Product Nomenclature Decoding

The detailed part number structure is fully explained. It codes for manufacturer, spectrum (UVA), package size (2835), package material (PCT), coating (Ag), viewing angle (100°), peak wavelength code, radiant flux bin, forward voltage range (3.0-4.0V), forward current (150mA), chip type (Vertical), chip size (15mil), chip quantity (1), and process type (Dispensing). This allows for precise specification when ordering.

8. Application Suggestions

8.1 Typical Application Scenarios

UV Nail Curing: The 365nm and 395nm wavelengths are effective for curing gel nail polishes. The 395nm light is more visible (purple-blue) and may cure slightly slower surface layers, while 365nm is more "invisible" and penetrates deeper.
Counterfeit Detection: Many security features, inks, and papers fluoresce under specific UVA wavelengths. These LEDs can illuminate such features for verification.
Insect Traps: Many flying insects are attracted to UVA light. These LEDs can serve as the lure in electronic bug zappers or monitoring traps.

8.2 Design Considerations

• Thermal Management: With a thermal resistance of 15°C/W and a max T_J of 90°C, proper heat sinking via the thermal pad/cathode is essential, especially when operating at high ambient temperatures or currents.
• Current Driving: Use a constant current driver set to 150mA (or lower as per the derating curve) to ensure stable output and longevity. The forward voltage bin should be considered for series configurations.
• Optical Design: The wide 100-degree viewing angle provides broad illumination. For focused beams, secondary optics may be required.
• ESD Precautions: Although rated for 2KV ESD, standard ESD handling procedures should still be followed during assembly.

9. Technical Comparison and Differentiation

While the datasheet does not compare directly with other products, key differentiators of this series can be inferred. The combination of a standard 2835 footprint (compatible with many existing designs), integrated ESD protection, and compliance with multiple environmental standards offers a balanced solution. The availability of two distinct peak wavelengths (365nm and 395nm) within the same mechanical package provides application flexibility. The detailed binning structure allows for high consistency in mass production.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED at 180mA continuously?
A: No. The Absolute Maximum Rating of 180mA is a stress limit, not an operating condition. The nominal operating current is 150mA. Continuous operation at 180mA would likely exceed the maximum junction temperature and reduce lifespan.

Q: What is the difference between the thermal pad and the electrical pads?
A: The thermal pad is electrically connected to the cathode. This means your PCB layout must connect the thermal pad to the same net as the cathode pad. It cannot be used as an isolated heatsink.

Q: How do I choose between the 365nm and 395nm wavelength?
A: It depends on your application's spectral sensitivity. 395nm is closer to visible violet light and is often used where some visible cue is acceptable (e.g., nail lamps). 365nm is deeper UVA, more "invisible," and may be better for applications requiring pure UV or where specific materials fluoresce more strongly at that wavelength.

Q: What does the "Derating Curve" mean for my design?
A: It defines the maximum safe operating current at different ambient/board temperatures. For example, if your PCB temperature at the LED mounting point reaches 80°C, the maximum allowable current drops significantly below 150mA. You must design your system to stay below this curve.

11. Practical Design and Usage Case

Case: Designing a Compact UV Inspection Pen. A designer needs a portable device to check currency. They select the ELUA2835TG0 for its small size and 2KV ESD rating (important for a handheld device). They choose the 365nm variant for strong fluorescence on security threads. They design a simple PCB with a coin cell battery, a current-limiting resistor set for ~100mA (to extend battery life and stay within safe limits without active cooling), and a switch. The thermal pad is connected to the cathode trace, which is made as large as possible on the PCB to act as a heatsink. The wide viewing angle eliminates the need for a lens, simplifying assembly.

12. Principle Introduction

UVA LEDs 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 specific wavelength of these photons (in the UVA range, 315-400nm) is determined by the bandgap energy of the semiconductor materials used in the LED chip, typically involving aluminum gallium nitride (AlGaN) or similar compounds. The vertical chip structure mentioned in the part number often refers to a design where the electrical current flows vertically through the chip, which can offer benefits in current spreading and thermal performance compared to lateral structures.

13. Development Trends

The UVA LED market is driven by trends towards miniaturization, increased efficiency (higher radiant flux per electrical watt), and improved reliability. There is ongoing development to push wavelengths deeper into the UVB and UVC ranges for sterilization applications, but UVA remains crucial for curing, sensing, and specialty lighting. Integration of UVA LEDs with sensors and smart drivers for closed-loop intensity control is an emerging trend. Furthermore, advancements in package materials are continuously improving resistance to UV-induced degradation, which is a key factor for long-term performance in UVA applications where the package itself is exposed to its own emitted radiation.