LED Ceramic 3535 Series 1W White LED Datasheet - Dimensions 3.5x3.5x?mm - Voltage 3.2V - Power 1W - English Technical Document

1. Product Overview

This document details the specifications for a high-power 1W white LED encapsulated in a robust ceramic 3535 surface-mount package. Ceramic packages offer superior thermal conductivity compared to traditional plastic packages, enabling better heat dissipation from the LED junction. This results in improved performance stability, longer lifespan, and higher reliability under demanding operating conditions. The product is designed for applications requiring high luminous output and excellent thermal management, such as automotive lighting, general illumination, and specialty lighting fixtures.

2. Technical Parameters Deep Dive

2.1 Absolute Maximum Ratings (Ts=25°C)

The following parameters define the limits beyond which permanent damage to the LED may occur. Operation at or near these limits is not recommended for extended periods.

• Forward Current (IF): 500 mA (Maximum continuous current).
• Forward Pulse Current (IFP): 700 mA (Pulse width ≤10ms, duty cycle ≤1/10).
• Power Dissipation (PD): 1700 mW.
• Operating Temperature (Topr): -40°C to +100°C.
• Storage Temperature (Tstg): -40°C to +100°C.
• Junction Temperature (Tj): 125°C (Maximum).
• Soldering Temperature (Tsld): Reflow soldering at 230°C or 260°C for 10 seconds maximum.

2.2 Electro-Optical Characteristics (Ts=25°C, IF=350mA)

These are the typical performance parameters under standard test conditions.

• Forward Voltage (VF): Typical 3.2V, Maximum 3.4V. This is the voltage drop across the LED when driven at 350mA.
• Reverse Voltage (VR): 5V (Maximum). Exceeding this voltage in reverse bias can damage the LED.
• Reverse Current (IR): Maximum 50 µA.
• Viewing Angle (2θ1/2): 120 degrees (Typical). This wide beam angle is suitable for general lighting applications.

3. Binning System Explanation

To ensure color and brightness consistency in production, LEDs are sorted into bins based on key parameters.

3.1 Correlated Color Temperature (CCT) Binning

The LED is available in standard CCT ranges, each associated with specific chromaticity regions on the CIE diagram. The typical CCTs and their corresponding bin codes are: 2700K (8A-8D), 3000K (7A-7D), 3500K (6A-6D), 4000K (5A-5D), 4500K (4A-4U), 5000K (3A-3U), 5700K (2A-2U), 6500K (1A-1U), and 8000K (0A-0U). Products are guaranteed to be within the ordered CCT's chromaticity region.

3.2 Luminous Flux Binning

Flux bins specify the minimum luminous output at 350mA. The actual flux may be higher. Examples include:

• 70 CRI Warm White (2700-3700K): Bins from 1Y (80-87 lm) to 2D (114-122 lm).
• 70 CRI Neutral White (3700-5000K): Bins from 1Z (87-94 lm) to 2F (130-139 lm).
• 70 CRI Cool White (5000-10000K): Bins from 2A (94-100 lm) to 2F (130-139 lm).
• 85 CRI variants are also available with corresponding flux bins (e.g., 1W: 70-75 lm for Warm White).

3.3 Forward Voltage Binning

Voltage is binned to aid in circuit design for current regulation. The bins are: Code 1 (2.8-3.0V), Code 2 (3.0-3.2V), Code 3 (3.2-3.4V), Code 4 (3.4-3.6V).

3.4 Model Numbering Rule

The part number structure is: T [Package Code] [Chip Count Code] [Lens Code] [Internal Code] - [Flux Code] [CCT Code]. For example, T1901PL(C,W)A decodes as: T (series), 19 (Ceramic 3535 package), P (1 high-power die), L (Lens code 01), (C,W) (CCT: Neutral White or Cool White), A (internal code), with Flux and CCT codes specified separately.

4. Performance Curve Analysis

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

The I-V curve shows the exponential relationship between current and voltage. Designers use this to select appropriate driver topology (constant current vs. constant voltage) and to calculate power dissipation (Vf * If). The typical Vf of 3.2V at 350mA is a key design point.

4.2 Forward Current vs. Relative Luminous Flux

This curve demonstrates that light output increases with current but not linearly. Efficiency typically decreases at higher currents due to increased heat (droop effect). Operating at the recommended 350mA provides a good balance of output and efficiency.

4.3 Junction Temperature vs. Relative Spectral Power

As junction temperature (Tj) rises, the LED's spectral output can shift, often causing a slight change in color (chromaticity shift) and a decrease in luminous flux. The ceramic package helps minimize Tj rise, thereby stabilizing optical performance.

4.4 Relative Spectral Power Distribution

The spectrum plot shows the intensity of light emitted at each wavelength. For white LEDs (typically phosphor-converted), it shows a blue peak from the die and a broader yellow/white peak from the phosphor. The area under the curve relates to total flux, and the shape determines Color Rendering Index (CRI) and CCT.

5. Mechanical & Packaging Information

5.1 Outline Dimensions

The LED uses a standard 3535 footprint (approximately 3.5mm x 3.5mm). The exact dimensional drawing shows the body size, lens shape, and terminal locations. Tolerances are specified as ±0.10mm for .X dimensions and ±0.05mm for .XX dimensions.

5.2 Recommended Pad Pattern & Stencil Design

A land pattern diagram is provided for PCB layout, ensuring proper solder joint formation and thermal connection. A corresponding stencil design guides solder paste application for reflow soldering. Proper pad design is critical for mechanical stability and heat transfer to the PCB.

5.3 Polarity Identification

The anode and cathode terminals must be correctly identified on the LED package and matched to the PCB layout. Incorrect polarity will prevent the LED from illuminating.

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Profile

The LED is compatible with standard lead-free reflow processes. The maximum body temperature during soldering should not exceed 260°C for 10 seconds. It is crucial to follow the recommended temperature profile (preheat, soak, reflow, cooling) to avoid thermal shock and ensure reliable solder joints without damaging the internal components or phosphor.

6.2 Handling & Storage Precautions

LEDs are sensitive to electrostatic discharge (ESD). Use appropriate ESD precautions during handling and assembly. Store in a dry, anti-static environment within the specified temperature range (-40°C to +100°C). Avoid exposure to moisture; if exposed, follow baking procedures before reflow.

7. Packaging & Ordering Information

7.1 Tape and Reel Specification

The LEDs are supplied on embossed carrier tape wound onto reels, suitable for automated pick-and-place assembly equipment. The tape dimensions (pocket size, pitch) are standardized.

7.2 Packing Quantity

Standard reel quantities are used (e.g., 1000 or 2000 pieces per reel). The outer packaging includes labels specifying part number, bin codes (flux, CCT, Vf), quantity, and lot number for traceability.

8. Application Suggestions

8.1 Typical Application Scenarios

• Automotive Lighting: Daytime running lights (DRLs), interior lighting, signal lights.
• General Illumination: LED bulbs, downlights, panel lights, street lights.
• Specialty Lighting: Portable lights, emergency lighting, architectural accent lighting.

8.2 Design Considerations

• Thermal Management: The primary design challenge. Use a PCB with adequate thermal vias and possibly a metal-core PCB (MCPCB) or heatsink to maintain a low thermal resistance path from the LED junction to ambient.
• Current Drive: Always use a constant-current driver, not a constant-voltage source, to ensure stable light output and prevent thermal runaway.
• Optics: Secondary optics (lenses, reflectors) may be needed to achieve the desired beam pattern.

9. Technical Comparison & Advantages

The ceramic 3535 package offers distinct advantages over plastic SMD packages (like 3528 or 5050) and even other ceramic packages:

• vs. Plastic Packages: Superior thermal conductivity, leading to lower junction temperature, higher maximum drive current potential, better lumen maintenance, and longer lifetime, especially in high-power applications.
• vs. Other Ceramic Packages: The 3535 footprint is a common industry standard, offering a good balance of size, power handling, and optical output, making it highly versatile for many lighting designs.

10. Frequently Asked Questions (FAQs)

10.1 What is the difference between the 70 CRI and 85 CRI versions?

CRI (Color Rendering Index) measures how naturally a light source reveals the colors of objects compared to a reference source. 85 CRI LEDs provide better color fidelity than 70 CRI LEDs, which is important for retail, museum, or high-quality residential lighting. The trade-off is typically a slightly lower luminous efficacy (lumens per watt) for higher CRI.

10.2 Can I drive this LED at 500mA continuously?

While the absolute maximum rating is 500mA, continuous operation at this current will generate significant heat. The recommended operating current is 350mA. To drive at 500mA, exceptional thermal management is required to keep the junction temperature well below 125°C, otherwise, lifetime and performance will degrade rapidly.

10.3 How do I interpret the flux bin code (e.g., 2B)?

The flux bin code guarantees a minimum luminous flux. For example, a 2B bin for 70 CRI Cool White guarantees a minimum of 100 lm at 350mA. The actual flux from the shipped parts will be between the min and max values for that bin (e.g., 100-107 lm) but is not guaranteed to be at the typical value.

11. Practical Design Case Study

Scenario: Designing a high-quality LED downlight with neutral white (4000K) light and good color rendering (CRI >80).
Selection: Choose an 85 CRI Neutral White LED in CCT bin 5x and a flux bin like 2A (94-100 lm min).
Thermal Design: Mount the LED on a 1.6mm thick MCPCB (Aluminum substrate). The MCPCB is attached to a heatsink with thermal interface material. Thermal simulation should confirm Tj < 100°C at an ambient of 45°C.
Electrical Design: Use a constant-current LED driver rated for 350mA output. Include protection against over-voltage and open/short circuits.
Optical Design: Pair the LED with a secondary lens to achieve a 30-degree beam angle for spotlighting.

12. Operating Principle

A white LED operates on the principle of electroluminescence in a semiconductor and phosphor conversion. Electrical current flows through a semiconductor chip (typically InGaN), causing it to emit photons in the blue or ultraviolet spectrum. These high-energy photons then strike a layer of phosphor material coating the chip. The phosphor absorbs some of these photons and re-emits light at longer, lower-energy wavelengths (yellow, red). The mixture of the unconverted blue light and the down-converted yellow/red light is perceived by the human eye as white light. The exact proportions determine the Correlated Color Temperature (CCT).

13. Technology Trends

The LED industry continues to evolve with several key trends impacting components like the ceramic 3535 LED:

• Increased Efficacy (lm/W): Ongoing improvements in chip design, phosphor technology, and package efficiency lead to more light output for the same electrical input, reducing energy consumption.
• Higher Reliability & Lifetime: Advancements in materials (like robust ceramics) and manufacturing processes are pushing rated lifetimes (L70/B50) beyond 50,000 hours.
• Improved Color Quality: Development of multi-phosphor blends and novel chip structures enables LEDs with very high CRI (90+), excellent color consistency (tight binning), and tunable white light.
• Miniaturization & Higher Power Density: The ability to handle more power in the same or smaller footprint (e.g., 3030, 2929 packages) is a constant trend, demanding ever-better thermal management solutions.
• Smart & Connected Lighting: LEDs are becoming integral parts of IoT systems, requiring drivers and sometimes the packages themselves to support dimming, color tuning, and data communication protocols.