SMD3528 Yellow LED Datasheet - Size 3.5x2.8mm - Voltage 2.2V - Power 0.144W - English Technical Document

1. Product Overview

The SMD3528 Yellow LED is a surface-mount device designed for general lighting, backlighting, and indicator applications. This single-die LED offers a compact form factor with a wide 120-degree viewing angle, making it suitable for applications requiring uniform illumination. The primary advantage of this component lies in its standardized binning system, which ensures consistent color and luminous flux output across production batches, crucial for applications demanding color uniformity.

The target market includes consumer electronics, automotive interior lighting, signage, and decorative lighting fixtures where reliable, low-power yellow illumination is required.

2. Technical Parameter Deep Dive

2.1 Absolute Maximum Ratings

The device is rated for operation under the following maximum conditions, measured at a solder point temperature (T_s) of 25°C. Exceeding these limits may cause permanent damage.

• Forward Current (I_F): 30 mA (Continuous)
• Forward Pulse Current (I_FP): 40 mA (Pulse width ≤10ms, Duty Cycle ≤1/10)
• Power Dissipation (P_D): 144 mW
• Operating Temperature (T_opr): -40°C to +80°C
• Storage Temperature (T_stg): -40°C to +80°C
• Junction Temperature (T_j): 125°C
• Soldering Temperature (T_sld): 230°C or 260°C for 10 seconds (Reflow soldering)

2.2 Electrical & Optical Characteristics

Typical performance is measured at T_s=25°C and I_F=20mA, unless otherwise specified.

• Forward Voltage (V_F): Typical 2.2V, Maximum 2.6V
• Reverse Voltage (V_R): 5V
• Dominant Wavelength (λ_d): 590 nm
• Reverse Current (I_R): Maximum 10 µA (at V_R=5V)
• Viewing Angle (2θ_1/2): 120 degrees

3. Binning System Explanation

A comprehensive binning system categorizes LEDs based on key performance parameters to guarantee consistency. The tolerance for luminous flux measurement is ±7%, and for voltage measurement is ±0.08V.

3.1 Luminous Flux Binning

Luminous flux is measured at I_F=20mA. The bin code defines the minimum and typical output.

• A2: Min 0.5 lm, Typ 1.0 lm
• A3: Min 1.0 lm, Typ 1.5 lm
• B1: Min 1.5 lm, Typ 2.0 lm
• B2: Min 2.0 lm, Typ 2.5 lm
• B3: Min 2.5 lm, Typ 3.0 lm

3.2 Wavelength Binning

The dominant wavelength is binned to control the precise shade of yellow.

• Y1: 585 nm to 588 nm
• Y2: 588 nm to 591 nm
• Y3: 591 nm to 594 nm

3.3 Forward Voltage Binning

Forward voltage is binned to aid in circuit design for current regulation.

• C: 1.8V to 2.0V
• D: 2.0V to 2.2V
• E: 2.2V to 2.4V
• F: 2.4V to 2.6V

3.4 Product Nomenclature Decoding

The model number follows a specific structure: T3200SYA. Based on the provided naming rules, this can be interpreted as a product with a specific internal code, a luminous flux bin, a color code (Y for Yellow), a die count (S for single small-power die), a lens code (00 for no lens), and a package code (32 for 3528).

4. Performance Curve Analysis

The datasheet includes several characteristic curves that are vital for understanding the LED's behavior under different operating conditions.

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

This curve shows the exponential relationship between applied forward voltage and the resulting current. It is essential for selecting the appropriate current-limiting resistor or driver circuit to ensure the LED operates within its specified current range and to prevent thermal runaway.

4.2 Forward Current vs. Relative Luminous Flux

This graph illustrates how light output increases with forward current. It typically shows a near-linear relationship within the recommended operating range, followed by a plateau or decrease at higher currents due to efficiency droop and increased junction temperature. Operating beyond the linear region is inefficient and accelerates degradation.

4.3 Junction Temperature vs. Relative Spectral Power

This curve demonstrates the thermal stability of the LED's color output. For this yellow AlInGaP LED, the relative spectral energy remains above 90% across a junction temperature range from 25°C to 125°C when driven at 20mA. This indicates good color stability over its operating temperature range, which is critical for applications where consistent color is required.

4.4 Spectral Power Distribution

The spectral curve shows a narrow peak centered around the dominant wavelength (590 nm), which is characteristic of monochromatic LEDs. The full width at half maximum (FWHM) of this peak determines the color purity. A narrower FWHM indicates a more saturated, pure yellow color.

5. Mechanical & Packaging Information

5.1 Physical Dimensions & Outline Drawing

The LED conforms to the standard SMD 3528 package dimensions: approximately 3.5mm in length, 2.8mm in width, and a typical height. Detailed mechanical drawings with tolerances (e.g., .X: ±0.10mm, .XX: ±0.05mm) are provided for PCB footprint design.

5.2 Recommended PCB Land Pattern & Stencil

A recommended solder pad layout and stencil aperture design are supplied to ensure proper solder joint formation during reflow soldering. Adhering to these guidelines prevents tombstoning, misalignment, and insufficient solder.

5.3 Polarity Identification

The cathode is typically marked by a green dot on the top of the LED package or a notch/chamfer on one side of the package body. Correct polarity must be observed during assembly.

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Parameters

The LED is compatible with standard infrared or convection reflow processes. The maximum body temperature during soldering must not exceed 230°C for 10 seconds or 260°C for 10 seconds. A standard reflow profile with preheat, soak, reflow, and cooling zones should be used, ensuring the peak temperature and time above liquidus are controlled.

6.2 Handling & Storage Precautions

• Store in a dry, anti-static environment within the specified temperature range (-40°C to +80°C).
• Use within 12 months of the manufacturing date under recommended storage conditions to maintain solderability.
• Avoid mechanical stress on the lens and wire bonds.
• Clean with isopropyl alcohol if necessary; avoid using ultrasonic cleaning.

7. Packaging & Ordering Information

7.1 Tape and Reel Specification

The product is supplied on embossed carrier tape wound on reels. Key dimensions of the carrier tape pockets are specified to ensure compatibility with standard SMD pick-and-place equipment. The cover tape peel strength is defined as 0.1N to 0.7N when peeled at a 10-degree angle.

7.2 Ordering Model Selection

Specific orderable part numbers are derived by combining the base model with the desired bin codes for luminous flux, wavelength, and forward voltage (e.g., T3200SYA-A2-Y2-D). Consult the full binning tables to select the combination that meets the application's requirements for brightness, color, and electrical characteristics.

8. Application Suggestions

8.1 Typical Application Circuits

The most common drive method is a constant current source or a simple series resistor with a DC voltage supply. The resistor value is calculated as R = (V_supply - V_F) / I_F. For applications requiring stable brightness or operating over a wide temperature range, a constant current driver is strongly recommended to compensate for the negative temperature coefficient of V_F.

8.2 Thermal Management Considerations

While the power dissipation is low, effective thermal management on the PCB is still important for long-term reliability. Ensure adequate copper area connected to the thermal pad (if applicable) or the cathode/anode pads to conduct heat away from the LED junction. Operating at or near the maximum rated current will generate more heat and requires more careful thermal design.

8.3 Design for Manufacturing (DFM)

Follow the recommended land pattern and stencil design. Maintain proper spacing between LEDs and other components to avoid shadowing or optical interference. Consider the 120-degree viewing angle when designing light guides or diffusers to achieve the desired illumination pattern.

9. Reliability & Quality Standards

9.1 Reliability Test Matrix

The product undergoes a series of stringent reliability tests based on JEDEC and MIL standards to ensure long-term performance. Key tests include:

• High/Low Temperature Operating Life (HTOL/LTOL): 1008 hours at 85°C/-40°C at maximum current.
• High Temperature High Humidity Operating Life (HTHH): 1008 hours at 60°C/90% RH at maximum current.
• Temperature Humidity Bias (THB) Test: 20 cycles between -20°C and 60°C with 60% RH.
• Thermal Shock: 100 cycles between -40°C and 125°C.

9.2 Failure Criteria

A test is considered a failure if any sample exhibits:

• Forward voltage shift > 200mV.
• Luminous flux degradation > 25% (for this yellow AlInGaP LED).
• Forward or reverse leakage current > 10 µA.
• Catastrophic failure (open or short circuit).

10. Technical Comparison & Differentiation

Compared to non-binned or generically specified LEDs, this product's key advantage is its guaranteed performance within tight bins for flux, color, and voltage. This eliminates the need for extensive sorting and matching by the end-user in applications requiring uniformity, such as multi-LED arrays or backlight units. The 120-degree viewing angle is wider than some competitor offerings, providing more diffuse light emission suitable for panel lighting.

11. Frequently Asked Questions (FAQ)

11.1 What is the difference between luminous flux bins A2 and B3?

Bin A2 guarantees a minimum output of 0.5 lm (typical 1.0 lm), while Bin B3 guarantees a minimum of 2.5 lm (typical 3.0 lm). B3 LEDs are approximately 2.5 to 3 times brighter than A2 LEDs at the same 20mA drive current. Select the bin based on the required brightness for your application.

11.2 Can I drive this LED at 30mA continuously?

Yes, 30mA is the maximum continuous forward current rating. However, operating at the absolute maximum rating will generate more heat and may reduce the long-term lifespan. For optimal reliability, it is recommended to operate at or below the typical drive current of 20mA, or implement robust thermal management if 30mA operation is necessary.

11.3 How do I interpret the wavelength bin code Y2?

A Y2 bin code means the dominant wavelength of the LED is between 588 nm and 591 nm. This represents a specific, controlled shade of yellow. If your application requires a very specific yellow hue (e.g., matching a corporate color), you must specify the corresponding wavelength bin.

11.4 Is a constant current driver necessary?

For a simple indicator, a series resistor with a stable voltage supply is often sufficient. For lighting applications where consistent brightness is critical, or where the ambient temperature varies significantly, a constant current driver is highly recommended. It compensates for the LED's changing forward voltage with temperature, ensuring stable light output.

12. Practical Application Examples

12.1 Automotive Interior Mood Lighting

An array of these yellow LEDs, all selected from the same luminous flux (e.g., B2) and wavelength (e.g., Y2) bins, can be used to create uniform ambient lighting in a vehicle's footwells or dashboard. The wide viewing angle helps blend light from discrete sources. A PWM-dimmable constant current driver allows for brightness adjustment.

12.2 Status Indicator Panel

In an industrial control panel, multiple yellow LEDs can serve as "warning" or "attention" indicators. Using LEDs from the same voltage bin (e.g., D) ensures that when driven from a common current-limiting resistor network, each LED will have very similar brightness, creating a professional, uniform appearance.

13. Technology Principle Introduction

This yellow LED is based on AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology. When a forward voltage is applied, electrons and holes recombine in the active region of the semiconductor die, releasing energy in the form of photons. The specific bandgap energy of the AlInGaP material system determines the wavelength of the emitted light, which in this case is in the yellow spectrum (~590 nm). The light is emitted from the chip, encapsulated in a silicone or epoxy lens that also provides environmental protection and determines the viewing angle.

14. Industry Trends & Developments

The SMD LED market continues to drive towards higher efficiency (more lumens per watt), improved color rendering, and tighter binning tolerances. While this 3528 package is a mature and widely adopted form factor, there is a general trend towards smaller packages (e.g., 2020, 1515) for high-density applications and mid-power packages (e.g., 3030, 5050) for higher flux output. The underlying AlInGaP technology for yellow and red LEDs is also being optimized for higher efficiency and better performance at elevated temperatures. Furthermore, intelligent binning and digital traceability are becoming more common to ensure supply chain consistency for high-end lighting applications.