IR LED 1206 Package Datasheet - Size 3.2x1.6x1.1mm - Voltage 1.7V - Power 110mW - Infrared 940nm - English Technical Document

1. Product Overview

The IR11-21C/L491/TR8 is a surface-mount infrared emitting diode housed in a miniature 1206 package. It is designed with a water-clear plastic encapsulation featuring a flat top-view inner lens. The primary function of this device is to emit infrared light at a peak wavelength of 940nm, which is spectrally optimized for compatibility with common silicon-based photodetectors and phototransistors. This makes it an ideal component for non-contact sensing and detection applications.

1.1 Core Advantages

• Compact Design: The small double-ended 1206 SMD footprint allows for high-density PCB mounting, saving valuable board space.
• High Reliability: Engineered for consistent performance and long-term stability in various operating conditions.
• Optical Efficiency: The integrated inner lens provides a controlled view angle of 80 degrees, enhancing light directionality.
• Environmental Compliance: The product is lead-free, compliant with RoHS, EU REACH, and halogen-free standards (Br <900ppm, Cl <900ppm, Br+Cl <1500ppm).
• Supply Chain Friendly: Supplied on 8mm tape on 7-inch diameter reels, compatible with automated pick-and-place assembly equipment.

1.2 Target Applications

This infrared LED is primarily intended for use as a light source in PCB-mounted infrared sensor systems. Typical applications include proximity sensors, object detection, touchless switches, and optical encoders where reliable infrared emission is required.

2. Technical Specifications

2.1 Absolute Maximum Ratings

The following ratings define the limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed.

• Continuous Forward Current (I_F): 65 mA
• Reverse Voltage (V_R): 5 V
• Operating Temperature (T_opr): -25°C to +85°C
• Storage Temperature (T_stg): -40°C to +85°C
• Soldering Temperature (T_sol): 260°C for ≤ 5 seconds
• Power Dissipation (P_d): 110 mW at or below 25°C free air temperature

2.2 Electro-Optical Characteristics (T_a = 25°C)

These parameters define the typical performance of the device under specified test conditions.

• Radiant Intensity (I_e): 1.0 mW/sr (Min), 2.8 mW/sr (Typ) at I_F = 20mA
• Peak Wavelength (λ_p): 940 nm (Typ)
• Spectral Bandwidth (Δλ): 30 nm (Typ)
• Forward Voltage (V_F): 1.3 V (Min), 1.7 V (Typ)
• View Angle (2θ_1/2): 80 degrees (Typ)
• Reverse Current (I_R): 10 µA (Max) at V_R = 5V

3. Performance Curve Analysis

3.1 Forward Current vs. Ambient Temperature

Figure 1 illustrates the derating curve for the maximum allowable forward current as a function of the ambient temperature. The device can handle the full 65mA only up to approximately 25°C. As temperature increases, the maximum current must be reduced linearly to prevent overheating and ensure reliability, reaching zero at around 100°C. This graph is critical for thermal management in the application design.

3.2 Spectral Distribution

Figure 2 shows the relative radiant intensity plotted against wavelength. The curve is centered at the typical peak wavelength of 940nm with a characteristic full width at half maximum (FWHM) of approximately 30nm. This narrow bandwidth ensures efficient coupling with silicon detectors, which have peak sensitivity in the near-infrared region.

3.3 Relative Intensity vs. Forward Current

Figure 3 depicts the relationship between relative radiant intensity and forward current. The output light intensity increases with current in a generally linear fashion within the recommended operating range. This characteristic allows for simple analog or PWM-based brightness control in sensing systems.

3.4 Forward Current vs. Forward Voltage

Figure 4 is the current-voltage (I-V) characteristic curve. It shows the exponential relationship typical of a diode. The forward voltage is relatively low, around 1.7V at 20mA, which contributes to lower power consumption in the system.

3.5 Radiation Pattern

Figure 5 presents the relative radiant intensity as a function of angular displacement from the central axis (view angle). The pattern is roughly Lambertian, with intensity dropping to half its peak value at approximately ±40 degrees from the center, confirming the 80-degree full viewing angle. This pattern is important for determining the coverage area of the emitted IR light.

4. Mechanical and Packaging Information

4.1 Package Dimensions

The device conforms to a standard 1206 (3216 metric) package outline. Key dimensions are as follows:

• Length (L): 3.20 mm ± 0.10 mm
• Width (W): 1.60 mm ± 0.10 mm
• Height (H): 1.10 mm ± 0.10 mm

Detailed mechanical drawings with land pattern recommendations are provided in the datasheet for PCB layout reference. The suggested pad design ensures proper soldering and mechanical stability.

4.2 Polarity Identification

The cathode is typically marked on the device body. Consult the package drawing for the exact marking scheme to ensure correct orientation during assembly.

5. Soldering and Assembly Guidelines

5.1 Storage and Handling

The LEDs are moisture-sensitive. They must be stored in their original moisture-proof bag at 10°C to 30°C and <90% RH before use. The shelf life is one year. Once the bag is opened, the "floor life" is 168 hours (7 days) when stored at 10°C to 30°C and ≤ 60% RH. Exceeded devices require baking (e.g., 96 hours at 60°C ± 5°C, <5% RH) before reflow soldering.

5.2 Reflow Soldering Profile

A lead-free reflow soldering profile is recommended. The peak temperature should not exceed 260°C, and the time above 240°C should be controlled. Reflow should not be performed more than two times on the same device. Avoid stressing the component during heating and do not warp the PCB after soldering.

5.3 Hand Soldering and Rework

If hand soldering is necessary, use a soldering iron with a tip temperature below 350°C and a power rating under 25W. Contact time per terminal should be limited to 3 seconds. For rework, a dual-head soldering iron is suggested to simultaneously heat both terminals and avoid thermal stress. The impact of rework on device characteristics should be verified beforehand.

6. Packaging and Ordering Information

6.1 Tape and Reel Specifications

The components are supplied on 8mm wide embossed carrier tape wound on 7-inch diameter reels. Each reel contains 2000 pieces. The carrier tape dimensions (pocket pitch, width, etc.) are specified to ensure compatibility with standard SMD assembly equipment.

6.2 Label Information

The reel label includes critical information such as the part number (P/N), lot number (LOT No.), quantity (QTY), peak wavelength (HUE), rank (CAT), and moisture sensitivity level (MSL).

7. Application Design Considerations

7.1 Current Limiting

Critical: An external current-limiting resistor must always be used in series with the LED. The forward voltage has a negative temperature coefficient, meaning it decreases as the junction temperature rises. Without a resistor, a small increase in voltage can cause a large, potentially destructive, increase in current (thermal runaway). The resistor value should be calculated based on the supply voltage (V_CC), the desired forward current (I_F), and the typical forward voltage (V_F) using Ohm's Law: R = (V_CC - V_F) / I_F.

7.2 Optical Design

Consider the 80-degree view angle when designing lenses, apertures, or light guides for the sensor system. The radiation pattern will affect the sensing range and field of view. For longer-range detection, external collimating optics may be necessary to focus the emitted light.

7.3 Detector Pairing

This LED's 940nm output is optimally matched to the spectral response of silicon photodiodes and phototransistors. Ensure the selected detector is sensitive in this wavelength region for maximum system signal-to-noise ratio.

8. Technical Comparison and Differentiation

Compared to older through-hole IR LEDs, this 1206 SMD version offers significant advantages in miniaturization and suitability for automated manufacturing. Its key differentiators within the SMD IR LED category are its combination of a relatively high radiant intensity (2.8 mW/sr typical) with a standard, widely adopted 1206 footprint, and its compliance with stringent environmental regulations. The integrated flat lens provides a consistent optical output compared to devices without an inner lens.

9. Frequently Asked Questions (FAQ)

9.1 Why is a current-limiting resistor mandatory?

LEDs are current-driven devices, not voltage-driven. Their I-V characteristic is exponential. Operating them directly from a voltage source, even one close to their nominal V_F, can lead to uncontrolled current flow, rapid heating, and immediate failure. The series resistor provides a linear, stable method to set the operating current.

9.2 What happens if the moisture sensitivity guidelines are not followed?

Moisture absorbed into the plastic package can vaporize rapidly during the high-temperature reflow soldering process. This can cause internal delamination, cracking of the package ("popcorning"), or damage to the wire bonds, leading to immediate failure or reduced long-term reliability.

9.3 Can this LED be used for data transmission?

While it emits modulated light, its primary design is for sensing applications. Its switching speed is not typically specified in this datasheet. For high-speed data transmission (e.g., IR remote controls), LEDs specifically characterized for fast response times should be selected.

10. Practical Design Example

Scenario: Designing a simple proximity sensor using this IR LED and a silicon phototransistor.

1. Drive Circuit: Connect the LED anode to a 5V supply via a current-limiting resistor. For a target I_F of 20mA and V_F of 1.7V, calculate R = (5V - 1.7V) / 0.02A = 165Ω. Use the nearest standard value (e.g., 160Ω or 180Ω). A transistor or microcontroller GPIO pin can switch the LED on/off.
2. Detection Circuit: Place the phototransistor nearby. When an object reflects the IR light back to the detector, its collector current increases. This current can be converted to a voltage using a load resistor and fed into a comparator or microcontroller ADC to detect the presence of the object.
3. Layout: Place the LED and detector close together on the PCB but ensure physical barriers or optical separators are used to prevent direct crosstalk (light from the LED going straight into the detector without reflection).

11. Operating Principle

An infrared LED is a semiconductor p-n junction diode. When a forward voltage is applied, electrons from the n-region recombine with holes from the p-region in the active region. This recombination process releases energy in the form of photons (light). The specific material composition (GaAlAs in this case) determines the bandgap energy, which defines the wavelength of the emitted photons, here in the infrared spectrum at 940nm. The inner lens shapes the emitted light into a specific radiation pattern.

12. Technology Trends

The trend in infrared components for sensing continues toward higher integration, smaller packages, and improved efficiency. There is a growing demand for IR LEDs with narrower spectral bandwidths and higher output power for longer-range applications like LiDAR and time-of-flight (ToF) sensing. Furthermore, integration of the IR emitter and detector into a single module simplifies system design. Environmental and regulatory compliance remains a critical driver for all electronic components.