LTPL-C035BH450 Blue LED Datasheet - 3.5x3.5x1.6mm - 3.3V Typ - 2.8W Max - 450nm Dominant Wavelength

1. Product Overview

The LTPL-C035BH450 is a high-power, surface-mount blue LED designed for solid-state lighting applications. It represents an energy-efficient and ultra-compact light source that combines the long lifetime and reliability inherent to Light Emitting Diodes with significant optical output. This device offers design flexibility and high brightness, enabling the replacement of conventional lighting technologies in various applications.

1.1 Key Features

• Integrated Circuit (I.C.) compatible drive.
• Compliant with RoHS (Restriction of Hazardous Substances) directives and lead-free (Pb-free) construction.
• Designed for lower operational energy costs.
• Contributes to reduced system maintenance costs due to its long operational life.

2. Outline Dimensions and Mechanical Data

The LED package has a compact footprint. Critical dimensions include a body size of approximately 3.5mm x 3.5mm. The lens height and ceramic substrate length/width have tighter tolerances of ±0.1mm, while other mechanical dimensions have a tolerance of ±0.2mm. It is crucial to note that the large thermal pad on the bottom of the package is electrically isolated (neutral) from the anode and cathode electrical pads, which is essential for proper thermal management and electrical isolation in circuit design.

3. Absolute Maximum Ratings

Stresses beyond these limits may cause permanent damage to the device. All ratings are specified at an ambient temperature (Ta) of 25°C.

• DC Forward Current (If): 700 mA
• Power Consumption (Po): 2.8 W
• Operating Temperature Range (Topr): -40°C to +85°C
• Storage Temperature Range (Tstg): -55°C to +100°C
• Maximum Junction Temperature (Tj): 125°C

Important Note: Operating the LED under reverse bias conditions for extended periods may result in component damage or failure.

4. Electro-Optical Characteristics

The following parameters are measured at Ta=25°C under a test condition of If = 350mA, which is a typical operating point.

• Forward Voltage (Vf): Minimum 2.8V, Typical 3.3V, Maximum 3.8V.
• Radiant Flux (Φe): Minimum 510mW, Typical 600mW, Maximum 690mW. This is the total radiant power output measured with an integrating sphere.
• Dominant Wavelength (Wd): Ranges from 440nm to 460nm, placing it in the blue spectrum.
• Viewing Angle (2θ1/2): Typically 130 degrees, defining the angular spread of the emitted light.
• Thermal Resistance, Junction to Case (Rth jc): Typically 9.5 °C/W with a measurement tolerance of ±10%. This parameter is critical for calculating the junction temperature rise under operating power.

5. Bin Code and Classification System

The LEDs are sorted (binned) based on key parameters to ensure consistency. The bin code is marked on each packing bag.

5.1 Forward Voltage (Vf) Binning

LEDs are categorized into five bins (V1 to V5) based on their forward voltage at 350mA, with each bin covering a 0.2V range from 2.8V to 3.8V. The tolerance within a bin is ±0.1V.

5.2 Radiant Flux (Φe) Binning

LEDs are sorted into six flux bins (W1 to W6), each representing a 30mW range from 510mW to 690mW at 350mA. The radiant flux tolerance is ±10%.

5.3 Dominant Wavelength (Wd) Binning

Four wavelength bins (D4I to D4L) are defined, each covering a 5nm range from 440nm to 460nm. The dominant wavelength tolerance is ±3nm.

6. Typical Performance Curves and Analysis

The datasheet provides several graphs illustrating device performance under various conditions (at 25°C unless noted).

6.1 Relative Radiant Flux vs. Forward Current

This curve shows that the optical output (radiant flux) increases with forward current but will eventually saturate and can decrease at very high currents due to efficiency droop and thermal effects. Operating near the typical 350mA provides a good balance of output and efficiency.

6.2 Relative Spectral Distribution

The graph depicts the narrow emission spectrum characteristic of a blue LED, centered around the dominant wavelength (e.g., 450nm). The spectral width (Full Width at Half Maximum) is typically narrow for monochromatic LEDs.

6.3 Radiation Pattern (Viewing Angle)

The polar diagram illustrates the spatial intensity distribution, confirming the wide 130-degree viewing angle. The pattern is typically Lambertian or near-Lambertian for this type of package.

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

This fundamental curve shows the exponential relationship between current and voltage for a diode. The forward voltage increases with current and is also temperature-dependent.

6.5 Relative Radiant Flux vs. Junction Temperature

This is a critical curve for thermal management. It demonstrates that the optical output of an LED decreases as the junction temperature (Tj) increases. Effective heat sinking is required to maintain Tj as low as possible to ensure stable, long-term light output and reliability.

7. Assembly and Application Guidelines

7.1 Soldering Recommendations

The device is suitable for reflow or hand soldering. A detailed reflow soldering profile is provided, specifying time and temperature limits for preheat, soak, reflow (with a peak temperature limit), and cooling. Key cautions include: avoiding rapid cooling rates, using the lowest possible soldering temperature, and limiting reflow cycles to a maximum of three. Hand soldering should be at 300°C max for 2 seconds max, performed only once. Dip soldering is not recommended or guaranteed.

7.2 Recommended PCB Pad Layout

A detailed land pattern (footprint) is provided for PCB design. This includes the dimensions and spacing for the two electrical pads (anode and cathode) and the large central thermal pad. Proper pad design is essential for mechanical stability, electrical connection, and most importantly, efficient heat transfer from the LED package to the PCB.

7.3 Drive Circuit Considerations

LEDs are current-driven devices. To ensure uniform brightness when connecting multiple LEDs in parallel, it is strongly recommended to use a separate current-limiting resistor in series with each LED (Circuit Model A). Connecting LEDs directly in parallel without individual resistors (Circuit Model B) is discouraged due to potential brightness mismatch caused by slight variations in the forward voltage (Vf) of individual devices. The LED must be operated under forward bias; continuous reverse current must be avoided to prevent damage.

7.4 Cleaning and Handling

If cleaning is necessary, only alcohol-based solvents like isopropyl alcohol should be used. Unspecified chemical cleaners may damage the LED package. The device should not be used in environments with high sulfur content (e.g., certain seals, adhesives) or in conditions of high humidity (over 85% RH), dew condensation, or corrosive atmospheres, as these can degrade the gold-plated electrodes and affect reliability.

8. Packaging Specifications

The LEDs are supplied on tape and reel for automated assembly. The datasheet includes detailed dimensions for both the embossed carrier tape (pocket size, pitch) and the reel (diameter, hub size). Key packing notes: pockets are sealed with cover tape, a 7-inch reel holds a maximum of 500 pieces, the minimum order quantity for remnants is 100 pieces, and a maximum of two consecutive missing components are allowed per reel. The packaging conforms to EIA-481-1-B standards.

9. Application Scenarios and Design Notes

9.1 Typical Applications

This high-power blue LED is suitable for applications requiring bright, efficient blue light. This includes architectural lighting, signage, automotive auxiliary lighting (where color mixing is used), entertainment/stage lighting, and as a primary light source in specialized medical or industrial equipment. Its blue emission is also fundamental for generating white light when combined with phosphors in phosphor-converted white LED packages.

9.2 Critical Design Considerations

• Thermal Management: The low thermal resistance (9.5°C/W) highlights the need for an effective thermal path. The PCB should use thermal vias under the thermal pad connected to a large copper plane or an external heatsink to keep the junction temperature well below the 125°C maximum.
• Current Drive: Use a constant current driver, not a constant voltage source. The recommended operating current is 350mA, but the driver should be designed considering the maximum forward voltage (up to 3.8V) and the required current regulation.
• Optical Design: The wide 130-degree viewing angle may require secondary optics (lenses, reflectors) to achieve the desired beam pattern for specific applications.
• Binning for Consistency: For applications where color or brightness uniformity is critical (e.g., multi-LED arrays), specify tight bin codes for radiant flux (Φe) and dominant wavelength (Wd) during procurement.

10. Technical Principles and Context

The LTPL-C035BH450 is based on semiconductor technology, specifically using materials like Indium Gallium Nitride (InGaN) to emit light in the blue spectrum when electrons recombine with holes across the device's bandgap. The dominant wavelength is determined by the precise composition of the semiconductor layers. The high power rating is achieved through efficient chip design, a package that effectively extracts light and manages heat, and robust internal interconnects. The trend in such LEDs is toward higher efficiency (more light output per electrical watt input), higher power density, and improved reliability at elevated operating temperatures, driven by advancements in epitaxial growth, packaging materials, and phosphor technology for white light conversion.