SMD LED 11-21/R6C-AR2S2B/2T Datasheet - Brilliant Red - 2.0x1.25x0.8mm - 2.35V Max - 60mW - English Technical Document

1. Product Overview

The 11-21 SMD LED is a compact, surface-mount device designed for indicator and backlighting applications. It utilizes an AlGaInP chip to produce a brilliant red light output. Its primary advantage lies in its miniature footprint, which enables higher packing density on PCBs, reduced storage space requirements, and ultimately contributes to the design of smaller end-user equipment. The component is lightweight, making it particularly suitable for space-constrained and portable applications.

Key product positioning includes use as a reliable, cost-effective indicator in consumer electronics, telecommunications equipment, and automotive interiors. Its core advantages are its small size, compatibility with automated assembly processes, and compliance with modern environmental regulations including RoHS, REACH, and halogen-free requirements.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

The device's operational limits are defined under conditions of Ta=25°C. Exceeding these ratings may cause permanent damage.

• Reverse Voltage (VR): 5V. Applying a voltage higher than this in reverse bias can break down the LED's PN junction.
• Continuous Forward Current (IF): 25 mA. This is the maximum DC current recommended for reliable long-term operation.
• Peak Forward Current (IFP): 60 mA. This pulsed current (1/10 duty cycle at 1kHz) can be withstood for short durations but is not for continuous use.
• Power Dissipation (Pd): 60 mW. This is the maximum power the package can dissipate without exceeding its thermal limits.
• Electrostatic Discharge (ESD): Human Body Model (HBM) 2000V. This rating indicates a moderate level of ESD robustness; proper handling procedures are still essential.
• Temperature Ranges: Operating from -40°C to +85°C; storage from -40°C to +90°C. This wide range suits many industrial and automotive environments.
• Soldering Temperature: Withstands reflow soldering at 260°C for 10 seconds or hand soldering at 350°C for 3 seconds per terminal.

2.2 Electro-Optical Characteristics

Typical performance is measured at Ta=25°C with an IF=20mA drive current, unless otherwise specified.

• Luminous Intensity (Iv): Ranges from a minimum of 140.0 mcd to a maximum of 285.0 mcd. The typical value falls within this range, with specific values determined by the binning code (R2, S1, S2).
• Viewing Angle (2θ1/2): A typical 60-degree angle, defining the cone within which the luminous intensity is at least half of the peak intensity.
• Peak Wavelength (λp): Typically 632 nm, indicating the wavelength at which the spectral emission is strongest.
• Dominant Wavelength (λd): Ranges from 617.5 nm to 633.5 nm. This is the single-wavelength perception of the LED's color by the human eye and is also subject to binning (E4-E7).
• Spectral Bandwidth (Δλ): Typically 20 nm, measured at half the maximum intensity (FWHM).
• Forward Voltage (VF): Ranges from 1.75V to 2.35V at 20mA. Lower VF bins (0, 1, 2) allow for more efficient system design, especially in battery-powered devices.
• Reverse Current (IR): Maximum of 10 μA when a 5V reverse bias is applied.

3. Binning System Explanation

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

3.1 Luminous Intensity Binning

Three bins are defined for luminous intensity at IF=20mA:

• R2: 140 mcd (Min) to 180 mcd (Max)
• S1: 180 mcd (Min) to 225 mcd (Max)
• S2: 225 mcd (Min) to 285 mcd (Max)

A tolerance of ±11% applies within each bin.

3.2 Dominant Wavelength Binning

Four bins are defined for dominant wavelength at IF=20mA:

• E4: 617.5 nm (Min) to 621.5 nm (Max)
• E5: 621.5 nm (Min) to 625.5 nm (Max)
• E6: 625.5 nm (Min) to 629.5 nm (Max)
• E7: 629.5 nm (Min) to 633.5 nm (Max)

A tolerance of ±1nm applies within each bin.

3.3 Forward Voltage Binning

Three bins are defined for forward voltage at IF=20mA:

• 0: 1.75 V (Min) to 1.95 V (Max)
• 1: 1.95 V (Min) to 2.15 V (Max)
• 2: 2.15 V (Min) to 2.35 V (Max)

A tolerance of ±0.1V applies within each bin.

The part number 11-21/R6C-AR2S2B/2T incorporates these bin codes, allowing precise selection for application requirements.

4. Performance Curve Analysis

While specific graphs are not detailed in the provided text, typical curves for this type of LED would include:

• Relative Luminous Intensity vs. Forward Current (I-I Curve): Shows a near-linear relationship at lower currents, saturating at higher currents due to thermal and efficiency droop.
• Forward Voltage vs. Forward Current (V-I Curve): Demonstrates the exponential relationship characteristic of a diode. The curve shifts with temperature.
• Relative Luminous Intensity vs. Ambient Temperature: Luminous output typically decreases as junction temperature rises. The rate of decrease is a key parameter for thermal management.
• Spectral Distribution: A plot showing the emission intensity across wavelengths, centered around the 632 nm peak with a ~20 nm FWHM.

Designers should consult these curves to understand behavior under non-standard conditions (different drive currents or temperatures).

5. Mechanical and Package Information

5.1 Package Dimensions

The 11-21 package has a very compact form factor. Key dimensions (typical, with ±0.1mm tolerance) include:

• Length: 2.0 mm
• Width: 1.25 mm
• Height: 0.8 mm

Detailed mechanical drawings specify pad layout, component outline, and recommended PCB land pattern to ensure proper soldering and mechanical stability.

5.2 Polarity Identification

The cathode is typically marked, often by a notch, a green marking, or a different pad size on the underside of the component. Correct orientation is critical for circuit function.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Profile

A lead-free (Pb-free) reflow profile is recommended:

• Pre-heating: 150–200°C for 60–120 seconds.
• Time Above Liquidus (217°C): 60–150 seconds.
• Peak Temperature: 260°C maximum, held for no more than 10 seconds.
• Heating Rate: Maximum 6°C/second.
• Time Above 255°C: Maximum 30 seconds.
• Cooling Rate: Maximum 3°C/second.

Reflow should not be performed more than twice.

6.2 Hand Soldering

If hand soldering is necessary:

• Use a soldering iron with a tip temperature < 350°C.
• Limit contact time to ≤ 3 seconds per terminal.
• Use an iron with a power rating ≤ 25W.
• Allow a minimum 2-second interval between soldering each terminal to prevent thermal shock.

6.3 Storage and Moisture Sensitivity

The LEDs are packaged in moisture-resistant barrier bags with desiccant.

• Before Opening: Store at ≤ 30°C and ≤ 90% Relative Humidity (RH).
• After Opening: The "floor life" is 1 year at ≤ 30°C and ≤ 60% RH. Unused parts should be resealed.
• Baking: If the desiccant indicates moisture absorption or storage time is exceeded, bake at 60 ±5°C for 24 hours before use.

7. Packaging and Ordering Information

7.1 Standard Packaging

The product is supplied in 8mm wide embossed carrier tape, wound on a 7-inch (178mm) diameter reel. Each reel contains 2000 pieces.

7.2 Label Explanation

The packaging label includes several key codes:

• CPN: Customer's Product Number (optional).
• P/N: The manufacturer's full part number (e.g., 11-21/R6C-AR2S2B/2T).
• QTY: Quantity of LEDs on the reel.
• CAT: Luminous Intensity bin code (e.g., S2).
• HUE: Chromaticity/Dominant Wavelength bin code (e.g., E6).
• REF: Forward Voltage bin code (e.g., 1).
• LOT No: Traceable manufacturing lot number.

8. Application Recommendations

8.1 Typical Application Scenarios

• Automotive Interiors: Backlighting for dashboard instruments, switches, and control panels.
• Telecommunications: Status indicators and keypad backlighting in phones and fax machines.
• Consumer Electronics: Flat backlighting for small LCDs, switch illumination, and symbolic indicators.
• General Indication: Power status, mode indication, and alert signals in a wide variety of electronic devices.

8.2 Critical Design Considerations

• Current Limiting: An external current-limiting resistor is MANDATORY. The LED's exponential V-I characteristic means a small voltage increase causes a large current surge, leading to immediate failure.
• Thermal Management: Ensure the PCB layout provides adequate thermal relief, especially when operating near maximum current or in high ambient temperatures.
• ESD Protection: Implement ESD protection on input lines and enforce proper handling during assembly, despite the 2000V HBM rating.
• Waveform Consideration: For PWM dimming, ensure the drive circuit can handle the peak current (IFP) within the specified duty cycle and frequency limits.

9. Technical Comparison and Differentiation

Compared to older through-hole LED packages (e.g., 3mm or 5mm), the 11-21 SMD LED offers significant advantages:

• Size & Density: Drastically smaller footprint enables miniaturization.
• Assembly Cost: Fully compatible with high-speed pick-and-place machines and reflow soldering, reducing assembly time and cost versus manual insertion.
• Performance: Often provides better thermal path to the PCB via its solder pads, potentially offering more stable performance over temperature.
• Reliability: Surface-mount construction eliminates lead bending stress and can improve vibration resistance.

Compared to other SMD LEDs (e.g., 0402, 0603), the 11-21 package may offer higher light output due to a potentially larger chip cavity, making it a good choice when slightly more brightness is needed in a still-compact format.

10. Frequently Asked Questions (FAQ)

Q: What resistor value should I use with this LED?

A: Use Ohm's Law: R = (Vsupply - VF) / IF. For a 5V supply, a typical VF of 2.0V, and desired IF of 20mA: R = (5 - 2.0) / 0.02 = 150 Ω. Choose the nearest standard value (e.g., 150Ω or 160Ω) and ensure the resistor's power rating is sufficient (P = I²R).

Q: Can I drive this LED without a constant current source?

A: Yes, a simple series resistor is sufficient for most indicator applications, as described above. A constant current driver is beneficial for applications requiring precise brightness control or operating over a wide voltage range.

Q: How do I interpret the part number 11-21/R6C-AR2S2B/2T?

A: While the exact decoding is proprietary, it generally follows this pattern: "11-21" is the package code. "R6C" likely indicates the chip technology/color (Brilliant Red). "AR2S2B" and "2T" are bin codes for intensity, wavelength, and voltage, corresponding to the S2, E6/E7, and 2 bins (or similar) as defined in the datasheet.

Q: Is this LED suitable for outdoor use?

A: The operating temperature range (-40°C to +85°C) suggests it can withstand many outdoor conditions. However, longevity in direct sunlight, UV exposure, and harsh weather depends on the encapsulation resin's durability, which is not specified. For critical outdoor applications, consult the manufacturer for reliability data.

11. Practical Design Case Study

Scenario: Designing a low-power status indicator for a portable medical device powered by a 3.3V battery.

Selection: The 11-21 LED is chosen for its small size and low power consumption.

Design Steps:

1. Current Selection: To maximize battery life, a drive current of 10mA is selected instead of 20mA. The datasheet's performance curves (if available) would show the relative intensity at 10mA.
2. Resistor Calculation: Using a conservative VF of 2.2V (from bin 2 max) for worst-case design: R = (3.3V - 2.2V) / 0.01A = 110 Ω.
3. Power Check: Resistor power dissipation: P = (0.01A)² * 110Ω = 0.011W. A standard 1/16W or 1/10W resistor is more than adequate.
4. PCB Layout: The recommended land pattern from the datasheet is used. Thermal relief connections are added to the LED pads to facilitate soldering while providing a good thermal path.
5. Software Consideration: The microcontroller GPIO pin driving the LED is configured as an open-drain output with the resistor connected to VCC, allowing the LED to be turned on by pulling the pin low.

This approach ensures reliable operation, long battery life, and easy manufacturability.

12. Operating Principle

The LED operates on the principle of electroluminescence in a semiconductor PN junction. The device uses an AlGaInP (Aluminum Gallium Indium Phosphide) chip. When a forward voltage exceeding the junction's threshold (approximately 1.8V) is applied, electrons from the n-type region and holes from the p-type region are injected into the active region. There, they recombine, releasing energy in the form of photons. The specific composition of the AlGaInP alloy determines the bandgap energy, which directly corresponds to the wavelength (color) of the emitted light—in this case, brilliant red (~632 nm). The clear resin encapsulation protects the chip and acts as a lens, shaping the light output into a 60-degree viewing angle.

13. Technology Trends

SMD LEDs like the 11-21 represent a mature and widely adopted technology. Current trends in this segment focus on:

• Increased Efficiency: Ongoing material science improvements aim to produce more lumens per watt (higher efficacy), allowing for brighter output at the same current or the same brightness with lower power consumption.
• Miniaturization: Continued reduction in package size (e.g., from 11-21 to even smaller footprints like 0805, 0603, 0402) to enable denser PCB designs.
• Improved Color Consistency: Tighter binning tolerances and advanced wafer-level manufacturing techniques are reducing color and brightness variation within a production batch.
• Enhanced Reliability: Development of more robust encapsulation resins and die attach materials to improve performance in high-temperature, high-humidity, or high-vibration environments, expanding into automotive and industrial markets.
• Integration: A trend towards integrating multiple LED chips (e.g., RGB), protection components like Zener diodes, or even current-limiting resistors into a single package to simplify circuit design and save board space.

While newer technologies like Micro-LEDs and advanced OLEDs emerge for display applications, conventional SMD indicator LEDs remain the dominant solution for status indication, panel backlighting, and decorative lighting due to their cost-effectiveness, reliability, and simplicity.