LTPL-C16FUVM385 UV LED Datasheet - 3.2x1.6x1.9mm - 3.3V - 23mW - 385nm - English Technical Document

1. Product Overview

The LTPL-C16 series represents a significant advancement in solid-state lighting technology, specifically engineered for ultraviolet (UV) applications. This product is an energy-efficient and ultra-compact light source that merges the long operational lifetime and high reliability inherent to Light Emitting Diodes (LEDs) with performance levels suitable for displacing conventional UV lighting systems. It offers designers considerable freedom due to its small form factor and surface-mount compatibility, enabling integration into space-constrained and automated production environments.

1.1 Key Features

• Fully compatible with standard automatic pick-and-place equipment for high-volume assembly.
• Designed to withstand both infrared (IR) and vapor phase reflow soldering processes.
• Packaged in a standard EIA-compliant format for broad compatibility.
• Input characteristics are compatible with standard integrated circuit (IC) drive levels.
• Manufactured as a green product, compliant with RoHS directives and is lead-free (Pb-free).

1.2 Target Applications

This UV LED is designed for a variety of industrial and manufacturing processes that require controlled UV exposure. Primary application areas include UV curing for adhesives and resins, UV marking and coding, UV-activated gluing processes, and the drying or curing of specialized printing inks. Its 385nm wavelength is particularly effective in initiating photochemical reactions.

2. Mechanical and Package Information

The device is housed in a compact surface-mount package. Critical outline dimensions are provided in the datasheet with all units in millimeters. The typical package body dimensions are approximately 3.2mm in length, 1.6mm in width, and 1.9mm in height. A tolerance of ±0.1mm applies to most dimensions unless otherwise specified. The datasheet includes detailed dimensional drawings showing top, side, and bottom views, including the recommended printed circuit board (PCB) attachment pad layout to ensure proper soldering and thermal management. The cathode is typically identified by a visual marker on the package.

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. All ratings are specified at an ambient temperature (Ta) of 25°C.

• Power Dissipation (Po): 160 mW
• DC Forward Current (If): 40 mA
• Reverse Voltage (Vr): 5 V
• Operating Temperature Range (Topr): -40°C to +85°C
• Storage Temperature Range (Tstg): -40°C to +100°C
• Junction Temperature (Tj): 100°C

4. Electro-Optical Characteristics

The following parameters define the typical performance of the LED under standard test conditions at Ta=25°C. The test current for most parameters is 20mA.

*Note: The reverse voltage test at Ir=10µA is for verifying a protective Zener function only. The device is not designed for continuous operation under reverse bias, which may cause failure.

4.1 Important Measurement Notes

• ESD Sensitivity: The device is sensitive to Electrostatic Discharge (ESD). Proper ESD precautions, including the use of grounded wrist straps and anti-static mats, are mandatory during handling.
• Test Standard: Radiant flux and peak wavelength are measured according to the CAS140B standard.
• Tolerances: Radiant flux measurement has a ±10% tolerance. Forward voltage measurement tolerance is ±0.1V. Peak wavelength measurement tolerance is ±3nm.

5. Bin Code and Classification System

To ensure consistency in application, LEDs are sorted (binned) based on key performance parameters. The bin code is marked on the packaging.

5.1 Forward Voltage (Vf) Binning

Measurement tolerance: ±0.1V @ If=20mA.

5.2 Radiant Flux (Φe) Binning

Measurement tolerance: ±10% @ If=20mA.

5.3 Peak Wavelength (λp) Binning

Tolerance: ±3nm @ If=20mA.

6. Performance Curve Analysis

The datasheet provides several characteristic curves essential for design and understanding device behavior under varying conditions.

6.1 Relative Emission Spectrum

A graph shows the spectral power distribution centered around the 385nm peak wavelength. The curve demonstrates a typical narrow-band emission characteristic of UV LEDs, which is crucial for applications requiring specific photon energy to initiate curing reactions.

6.2 Relative Radiant Flux vs. Forward Current

This curve illustrates the relationship between optical output and drive current. The radiant flux increases super-linearly with current at lower levels and tends to saturate at higher currents due to thermal and efficiency droop effects. This informs the selection of an optimal operating point for balancing output and longevity.

6.3 Forward Current vs. Forward Voltage (I-V Curve)

The I-V curve shows the exponential relationship typical of a diode. The knee voltage is around the typical 3.3V. This curve is vital for designing the current-limiting circuitry to ensure stable operation and prevent thermal runaway.

6.4 Relative Radiant Flux vs. Junction Temperature

This graph depicts the negative impact of rising junction temperature (Tj) on optical output. As Tj increases, the radiant flux decreases. This highlights the critical importance of effective thermal management in the PCB design to maintain consistent output performance and device reliability over time.

7. Assembly and Process Guidelines

7.1 Reflow Soldering Profile

A detailed temperature-time profile is provided for lead-free (Pb-free) reflow soldering processes. Key parameters include:

• Preheat: 150-200°C for a maximum of 120 seconds.
• Peak Temperature: Maximum of 260°C measured on the package body surface.
• Time Above Liquidus: Recommended to be within standard process windows.
• Cooling Rate: A rapid cooling process is not recommended.

The profile may need adjustment based on specific solder paste characteristics. The lowest possible soldering temperature that achieves a reliable joint is always recommended to minimize thermal stress on the LED.

7.2 Cleaning

If post-assembly cleaning is necessary, only specified chemicals should be used. Unspecified chemicals may damage the package epoxy. Acceptable methods include immersion in ethyl alcohol or isopropyl alcohol at room temperature for less than one minute.

7.3 Hand Soldering

If hand soldering is unavoidable, extreme care must be taken:

• Iron Temperature: Maximum 300°C.
• Soldering Time: Maximum 3 seconds per lead.
• Frequency: This should be performed only once to prevent thermal damage.

8. Packaging Specifications

The components are supplied in tape-and-reel packaging suitable for automated assembly equipment.

• Tape Dimensions: Detailed drawings specify pocket pitch, width, and cover tape placement.
• Reel Specifications: Standard 7-inch (178mm) reel.
• Quantity per Reel: Typically 1500 pieces.
• Missing Components: A maximum of two consecutive empty pockets is allowed.
• Standards: Packaging conforms to EIA-481-1-B specifications.

9. Reliability and Handling Cautions

9.1 Application Scope

This product is intended for use in standard commercial and industrial electronic equipment. It is not designed or qualified for safety-critical applications where failure could risk life or health (e.g., aviation, medical life-support, transportation control). For such applications, consultation with the manufacturer is required.

9.2 Moisture Sensitivity and Storage

The package is rated Moisture Sensitivity Level (MSL) 3 per JEDEC J-STD-020.

• Sealed Bag: Store at ≤30°C and ≤90% RH. Use within one year of the bag seal date.
• Opened Bag: Store at ≤30°C and ≤60% RH. Complete soldering within 168 hours (7 days) of exposure to factory ambient conditions.
• Baking: If the humidity indicator card turns pink (≥10% RH) or the 168-hour floor life is exceeded, bake the LEDs at 60°C for at least 48 hours before use. Reseal any unused parts with desiccant.

9.3 Drive Method

LEDs are current-operated devices. To ensure uniform brightness and prevent current hogging when driving multiple LEDs in parallel, each LED or parallel string must be paired with its own current-limiting resistor. A constant current driver is the recommended method for optimal performance and stability, as it compensates for variations in forward voltage and provides consistent optical output regardless of temperature-induced Vf shifts.

10. Design Considerations and Application Notes

10.1 Thermal Management

Given the negative correlation between junction temperature and radiant flux, effective heat sinking is paramount. The recommended PCB pad layout is designed to aid heat dissipation. Using a PCB with thermal vias connecting the pad to internal ground planes or an external heatsink can significantly improve performance and lifespan by keeping the junction temperature low.

10.2 Optical Design

The 135-degree viewing angle provides a broad emission pattern. For applications requiring focused or collimated UV light, secondary optics such as lenses or reflectors will be necessary. The material of these optics must be transparent to 385nm UV radiation (e.g., specialized glasses or UV-stable plastics like PMMA).

10.3 Electrical Design

Circuit design must account for the forward voltage binning. The power supply must be capable of delivering the required voltage to the LED plus the voltage drop across the current-limiting resistor or driver circuit, even for LEDs from the highest Vf bin (V3, up to 4.0V). Protection against reverse voltage connection and transient voltage spikes is also advised.

10.4 Comparison with Conventional UV Sources

Compared to traditional UV sources like mercury-vapor lamps, this LED offers distinct advantages: instant on/off capability, no warm-up time, longer operational lifetime (tens of thousands of hours), significantly smaller size, lower heat generation, and the absence of hazardous materials like mercury. The narrowband emission at 385nm can also be more efficient for specific photoinitiators used in curing processes, reducing energy waste.

11. Frequently Asked Questions (FAQ)

11.1 What is the typical operating current?

The standard test condition and typical operating point is 20mA DC. The absolute maximum continuous current is 40mA, but operating at or near this limit will reduce lifetime and increase junction temperature. For optimal reliability, derating the current is recommended.

11.2 How do I interpret the bin code on the bag?

The bin code (e.g., V2R6P3S) indicates the specific performance group for that batch of LEDs. V2 means Vf between 3.2-3.6V, R6 means radiant flux between 20-22mW, and P3S means peak wavelength between 385-390nm. Using LEDs from the same bin ensures consistency in a design.

11.3 Can I drive this LED with a constant voltage source?

It is strongly discouraged. The forward voltage of an LED has a negative temperature coefficient and varies from unit to unit. Driving with a constant voltage can lead to thermal runaway, where increasing current causes more heat, which lowers Vf, causing even more current, ultimately destroying the device. Always use a constant current source or a voltage source with a series current-limiting resistor.

11.4 What is the expected lifetime?

While the datasheet does not specify an L70 or L50 lifetime (time to 70% or 50% of initial light output), LEDs typically have lifetimes exceeding 25,000 to 50,000 hours when operated within their specified ratings and with proper thermal management. Lifetime is primarily determined by junction temperature; lower Tj equates to longer life.

12. Conclusion

The LTPL-C16FUVM385 is a highly capable and reliable UV LED source designed for modern, automated manufacturing environments. Its ultra-compact size, surface-mount design, and specific 385nm output make it an ideal choice for replacing bulkier, less efficient conventional UV lamps in curing, marking, and adhesive applications. Successfully integrating this component requires careful attention to drive current control, thermal management on the PCB, and adherence to the specified reflow soldering and moisture handling procedures. By following the guidelines in this datasheet, designers can leverage its benefits to create efficient, long-lasting, and compact UV illumination systems.