LED C3535 Series Specifications - Size 3.45x3.45x2.20mm - Voltage 2.6-3.4V - Power 6800mW - Color Temperatures 2700K-6500K - English Technical Documentation

1. Product Overview

The Refond RF-AL-C3535L2K1**-H4 is a high-power white LED designed for general lighting applications. It is fabricated using a blue chip combined with phosphors to produce white light. The LED package dimensions are 3.45mm x 3.45mm x 2.20mm, making it suitable for compact lighting fixtures.

1.1 General Description

This LED utilizes a ceramic package which provides excellent thermal management and high reliability. It has a viewing angle of 120 degrees, making it ideal for wide-area illumination. The component is compatible with all SMT assembly and solder processes and is supplied on tape and reel for automated manufacturing. It is RoHS compliant, meeting environmental standards.

1.2 Features

• Ceramic package for superior heat dissipation
• 120° viewing angle
• High reliability
• Suitable for all SMT assembly and solder process
• Available on tape and reel (1000 pcs/reel)
• RoHS compliant

1.3 Applications

The LED is designed for a wide range of lighting applications including:

• Warning lights, downlights, wash wall lights, spot lights, street lights
• Plant lighting, landscape lighting, stage photography light
• Hotels, markets, offices, household and other indoor uses
• General use

2. Technical Parameters Deep Analysis

2.1 Electrical / Optical Characteristics (Ts=25°C)

All measurements are performed under the standardized environment of Refond at a solder temperature of 25°C. The forward voltage (VF) is measured at IF=350mA and ranges from 2.6V (min) to 3.4V (max), with typical values depending on the bin. The luminous flux varies by model number:

• RF-AL-C3535L2K127-H4: 140-170 lm @ 350mA, 260-320 lm @ 700mA
• RF-AL-C3535L2K130-H4: 150-180 lm @ 350mA, 280-340 lm @ 700mA
• RF-AL-C3535L2K135-H4: 160-190 lm @ 350mA, 300-360 lm @ 700mA
• RF-AL-C3535L2K140-H4: 160-190 lm @ 350mA, 300-360 lm @ 700mA
• RF-AL-C3535L2K145-H4: 160-190 lm @ 350mA, 300-360 lm @ 700mA
• RF-AL-C3535L2K150-H4: 160-190 lm @ 350mA, 300-360 lm @ 700mA
• RF-AL-C3535L2K157-H4: 160-190 lm @ 350mA, 300-360 lm @ 700mA
• RF-AL-C3535L2K160-H4: 160-190 lm @ 350mA, 300-360 lm @ 700mA
• RF-AL-C3535L2K165-H4: 150-180 lm @ 350mA, 280-340 lm @ 700mA

The correlated color temperature (CCT) for each model corresponds to the last two digits of the part number: 27=2700K, 30=3000K, 35=3500K, 40=4000K, 45=4500K, 50=5000K, 57=5700K, 60=6000K, 65=6500K. Color rendering index (Ra) is minimum 80 at IF=350mA. Reverse current is less than 10 μA at VR=5V. Viewing angle is 120 degrees. Thermal resistance (junction to solder point) is typically 1.90°C/W at IF=700mA and Ta=25°C.

2.2 Absolute Maximum Ratings

The absolute maximum ratings must never be exceeded under any circumstances:

• Power Dissipation (PD): 6800 mW
• Forward Current (IF): 2000 mA
• Peak Forward Current (IFP): 3000 mA (1/10 duty cycle, 0.1ms pulse width)
• Reverse Voltage (VR): 5 V
• Electrostatic Discharge (HBM): 2000 V
• Operating Temperature (TOPR): -40°C to +85°C
• Storage Temperature (TOPR): -40°C to +85°C
• Junction Temperature (TJ): 125°C

3. Binning System Explanation

3.1 Forward Voltage and Luminous Intensity Bins (IF=350mA)

The LED is sorted into bins for forward voltage and luminous flux to ensure consistency. Voltage bins: F0 (2.6-2.8V), G0 (2.8-3.0V), H0 (3.0-3.2V), I0 (3.2-3.4V). Luminous flux bins: FC6 (140-150 lm), FC7 (150-160 lm), FC8 (160-170 lm), FC9 (170-180 lm), FD1 (180-190 lm). Chromaticity coordinates are defined for each CCT region in the CIE 1931 color space, with multiple sub-regions (e.g., 27A, 27B, 27C, 27D for 2700K). The detailed coordinate tables are provided in the specification.

4. Performance Curves Analysis

4.1 Forward Voltage vs. Forward Current

Figure 1-6 shows a nearly linear relationship: at 2.6V forward voltage, current is approximately 200mA, increasing to about 1600mA at 3.3V. This curve helps designers set proper current limiting.

4.2 Forward Current vs. Relative Intensity

Figure 1-7 illustrates that relative intensity increases linearly with forward current up to about 1000mA, then begins to saturate. At 1600mA, relative intensity reaches approximately 3.5 times the intensity at 350mA.

4.3 Temperature vs. Relative Intensity

Figure 1-8 shows that as solder point temperature (Ts) increases from 25°C to 125°C, relative intensity drops linearly to about 0.85 at 125°C. This must be considered in thermal management.

4.4 Ts Temperature vs. Forward Current Derating

Figure 1-9 provides a derating curve: at Ts=25°C, maximum forward current is 1600mA; at Ts=85°C, it reduces to about 600mA. This ensures junction temperature does not exceed 125°C.

4.5 Radiation Diagram (Viewing Angle)

Figure 1-10 shows the radiation pattern. Relative luminous intensity is maximum at 0° and drops to 50% at approximately ±60°, consistent with a 120° viewing angle.

4.6 Spectrum Distribution

Figure 1-11 displays the relative emission intensity vs. wavelength for 4000K and 5000K CCT at Ra80. The spectra peak around 450nm (blue) with a broad phosphor emission from 500nm to 700nm.

5. Mechanical and Packaging Information

5.1 Package Dimensions

The LED package is 3.45mm x 3.45mm x 2.20mm. The top view shows a central emitting area with two anode/cathode pads. The bottom view indicates a thermal pad (size 3.30mm x 3.30mm) and a polarity marking (a small circle near pin 1). The soldering pattern (Figure 1-5) recommends a 3.50mm x 3.40mm pad with a central thermal pad of 1.30mm width. All dimensions are in millimeters with tolerance ±0.2mm unless otherwise noted.

5.2 Carrier Tape and Reel Dimensions

The carrier tape has a width of 12.0mm, pocket pitch of 4.0mm, and component depth of 3.9mm. The reel has a diameter of 178mm and width of 14.0mm. Each reel contains 1000 pieces. The packaging includes a moisture barrier bag and desiccant.

5.3 Label Information

The label includes Part Number, Spec Number, Lot Number, Bin Code (including luminous flux bin and chromaticity bin XY), Forward Voltage bin, Quantity, and Date. The cardboard box dimensions are standard for shipping.

6. Soldering and Assembly Guidelines

6.1 SMT Reflow Soldering Profile

The recommended reflow profile (Figure 3-1) specifies: average ramp-up rate ≤3°C/s, preheat from 150°C to 200°C for 60-120 seconds, time above 217°C (TL) up to 60 seconds, peak temperature 260°C with maximum time (tp) of 10 seconds within 5°C of peak. Cooling rate ≤6°C/s. Total time from 25°C to peak should not exceed 8 minutes. Reflow soldering should not exceed two times. If hand soldering is required, use iron temperature <300°C for less than 3 seconds, only once.

6.2 Handling Precautions

• The LED encapsulant is silicone, which is soft. Avoid applying pressure on the top surface. Use picking nozzles with proper force.
• Do not mount on warped PCBs. After soldering, do not warp the board.
• Avoid mechanical stress or rapid cooling after soldering.
• The operating environment must have sulfur content less than 100PPM in mating materials. Bromine single content <900PPM, Chlorine single content <900PPM, total Bromine+Chlorine <1500PPM in external materials.
• VOCs from fixture materials can discolor the silicone; avoid outgassing adhesives.
• Handle components by the side surfaces using forceps or appropriate tools; do not touch the silicone lens directly.
• Always include current-limiting resistors in the driving circuit. Reverse voltage can cause damage.
• Thermal design is critical; ensure junction temperature does not exceed 125°C.
• Clean using isopropyl alcohol if needed; ultrasonic cleaning is not recommended.
• Storage: before opening aluminum bag, temperature ≤30°C, humidity <75% RH, within 6 months. After opening, use within 168 hours at ≤30°C, <60% RH. If exceeded, bake at 60±5°C, <5% RH for 24 hours.
• LEDs are sensitive to ESD and EOS; proper precautions must be taken.

7. Packaging and Ordering Information

The standard packaging is 1000 pieces per reel. The carrier tape has a 100 empty pocket leader and trailer. Moisture barrier bag with desiccant is used. The product is identified by a 16-digit part number (RF-AL-C3535L2K1**-H4), where the last two digits indicate the CCT bin. The bin code on the label includes VF bin and chromaticity bin. Cardboard box dimensions are standard for shipping multiple reels.

8. Application Recommendations

8.1 Typical Use Cases

This LED is suitable for warning lights, downlights, wall wash lights, spotlights, street lights, plant lighting, landscape lighting, stage photography light, and general indoor lighting in hotels, markets, offices, and homes. Its high luminous flux (up to 190 lm at 350mA) and wide viewing angle make it versatile.

8.2 Design Considerations

When designing circuits, ensure current through each LED does not exceed absolute maximum ratings. Use proper thermal management (heat sinking) to keep junction temperature below 125°C. The thermal pad on the bottom must be soldered to a PCB thermal land with adequate copper area. For parallel arrays, consider current sharing resistors. For series strings, ensure total voltage does not exceed driver capability. Because the LED has a low thermal resistance (1.9°C/W), good PCB thermal design is essential.

9. Technical Comparison

Compared to standard PLCC packages, the ceramic package of the C3535 offers lower thermal resistance and higher reliability, making it suitable for high-current applications up to 2A. The 120° viewing angle is wider than typical mid-power LEDs (often 120°-140°) and narrower than some chip-scale packages. The CRI of 80 meets most general lighting requirements. The availability of multiple CCT bins (2700K-6500K) provides flexibility for different ambiance needs.

10. Frequently Asked Questions

Q: What is the maximum current at a solder point temperature of 85°C?
A: From the derating curve (Figure 1-9), at Ts=85°C the maximum forward current is approximately 600mA.

Q: Can I run this LED at 700mA continuously?
A: Yes, the typical luminous flux at 700mA is given in the table. However, ensure that the junction temperature does not exceed 125°C by providing adequate heat sinking.

Q: How should I store the LEDs after opening the moisture barrier bag?
A: Store at ≤30°C and <60% RH. Use within 168 hours. If exceeded, bake at 60±5°C for 24 hours.

Q: What is the typical viewing angle?
A: The viewing angle is 120 degrees (half angle ±60° at 50% intensity).

Q: Does the LED require a reverse voltage protection diode?
A: Yes, reverse voltage above 5V can damage the LED. Always ensure the driving circuit does not apply reverse voltage.

11. Practical Application Example

Consider a downlight design using 10 LEDs in series. At IF=350mA, each LED drops approximately 3.0V (typical), so total forward voltage is 30V. Use a constant current driver rated for 350mA and 30-40V output. The thermal management: each LED dissipates about 1.05W (3.0V*0.35A). With thermal resistance of 1.9°C/W, the junction temperature rise above solder point is about 2°C. If ambient temperature is 25°C, the solder point temperature can be kept low with a good heat sink, ensuring long life.

12. Principles of Operation

The white LED uses a blue-emitting InGaN chip coated with yellow phosphor (typically YAG:Ce). The blue light excites the phosphor, which emits yellow light. The combination of blue and yellow appears white. The exact CCT is controlled by the phosphor composition and thickness. The LED chip is mounted on a ceramic substrate with metal pads for electrical and thermal connection. The silicone lens encapsulates the chip and phosphor, providing protection and light extraction.

13. Technology Trends

The industry trend for high-power LEDs is moving toward ceramic packages with low thermal resistance to support higher drive currents and smaller footprints. The C3535 package is a standard size (3.45mm x 3.45mm) that balances light output and thermal performance. Future developments may include higher efficacy (lm/W) and improved color rendering (CRI >90) while maintaining reliability. Refond's C3535 series addresses these needs with a wide CCT range and high flux options.