1.6mm Round Subminiature Infrared LED HIR26-21C/L289/TR8 Datasheet - Size 1.6mm - Wavelength 850nm - English Technical Document

1. Product Overview

The HIR26-21C/L289/TR8 is a subminiature surface-mount device (SMD) infrared emitting diode. It is designed for applications requiring a compact, reliable infrared source compatible with modern automated assembly processes. The device features a 1.6mm round package with a water-clear plastic encapsulation and a spherical top lens, optimizing its optical output.

Its core advantage lies in its spectral matching with silicon photodetectors (photodiodes and phototransistors), making it highly efficient for sensing systems. The device is constructed using GaAlAs (Gallium Aluminum Arsenide) chip material, which is standard for high-performance infrared emitters in this wavelength range.

The target market includes designers and manufacturers of consumer electronics, industrial sensors, and automation equipment where space is constrained and reliable infrared signaling or sensing is required.

2. Technical Parameter Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation outside these limits is not advised.

• Continuous Forward Current (I_F): 65 mA. This is the maximum DC current that can be applied continuously at an ambient temperature (T_a) of 25°C.
• Peak Forward Current (I_FP): 1.0 A. This high current is permissible only under pulsed conditions with a pulse width ≤100μs and a duty cycle ≤1%. This is typical for remote control applications where brief, high-power bursts are used.
• Reverse Voltage (V_R): 5 V. Exceeding this reverse bias voltage can cause junction breakdown.
• Operating Temperature (T_opr): -40°C to +85°C. The device is rated for industrial temperature ranges.
• Storage Temperature (T_stg): -40°C to +100°C.
• Soldering Temperature (T_sol): 260°C for a duration not exceeding 5 seconds, compatible with lead-free reflow processes.
• Power Dissipation (P_d): 130 mW at or below 25°C free air temperature. This rating considers both electrical power conversion and the device's ability to dissipate heat.

2.2 Electro-Optical Characteristics

These parameters are measured at T_a=25°C and define the device's performance under typical operating conditions.

• Radiant Intensity (I_e): The optical power output per solid angle (steradian). At a forward current of 20mA, the typical value is 17 mW/sr (minimum 10 mW/sr). Under pulsed conditions (100mA, ≤100μs, duty ≤1%), the typical radiant intensity rises significantly to 85 mW/sr, highlighting the benefit of pulsed operation for peak output.
• Peak Wavelength (λ_p): 850 nm (typical). This is in the near-infrared spectrum, which is ideal for silicon-based detectors and is less visible to the human eye than shorter wavelengths like 940nm, while still offering good atmospheric transmission.
• Spectral Bandwidth (Δλ): 30 nm (typical). This defines the range of wavelengths emitted, centered around the peak wavelength.
• Forward Voltage (V_F): At 20mA, the typical forward voltage is 1.40V (range 1.20V to 1.70V). At the pulsed current of 100mA, V_F increases to a typical 1.60V (range 1.40V to 2.20V). This information is critical for driver circuit design and power supply selection.
• Reverse Current (I_R): Maximum 10 μA at a reverse voltage of 5V, indicating good junction quality.
• View Angle (2θ_1/2): 25 degrees (typical). This is the full angle at which the radiant intensity drops to half of its peak value (on-axis). A 25° angle provides a relatively focused beam, suitable for directed sensing or signaling.

3. Performance Curve Analysis

The datasheet provides several key graphs for understanding device behavior under varying conditions.

3.1 Forward Current vs. Ambient Temperature

This curve shows the derating of the maximum allowable continuous forward current as the ambient temperature increases above 25°C. To prevent overheating, the current must be reduced linearly as temperature rises towards the maximum operating limit of 85°C. Designers must use this graph to ensure reliable operation in their application's thermal environment.

3.2 Spectral Distribution

This graph plots relative radiant intensity against wavelength, visually confirming the 850nm peak and the approximately 30nm spectral bandwidth. It shows the device emits a relatively pure infrared light centered at the specified wavelength.

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

This fundamental characteristic curve shows the exponential relationship between current and voltage for a diode. It is essential for determining the operating point and for designing current-limiting circuitry. The curve will shift with temperature.

3.4 Radiant Intensity vs. Forward Current

This graph illustrates the optical output as a function of drive current. It typically shows a sub-linear relationship, where efficiency (radiant intensity per mA) may decrease at very high currents due to thermal and other effects. The graph helps optimize the drive current for the desired optical output level.

3.5 Relative Radiant Intensity vs. Angular Displacement

This polar plot visually represents the view angle and radiation pattern of the LED. It shows how the intensity diminishes as the observation angle moves away from the central axis (0°), dropping to 50% at approximately ±12.5° (confirming the 25° full viewing angle). This is crucial for optical system design, alignment, and understanding the coverage area of the emitted light.

4. Mechanical and Packaging Information

4.1 Package Dimensions

The device is a double-ended SMD package with a 1.6mm body diameter. Detailed mechanical drawings in the datasheet provide all critical dimensions including overall height, lead spacing, and lens geometry. All dimensions are in millimeters with a standard tolerance of ±0.1mm unless otherwise specified.

4.2 Pad Design and Stencil Recommendation

To ensure reliable soldering and avoid issues like solder balling, a suggested pad layout and stencil design are provided. Key recommendations include:

• Solder Paste: Sn/Ag3.0/Cu0.5 (a common lead-free alloy).
• Stencil Thickness: 0.10mm.
• The stencil aperture drawing shows a pattern designed to control paste volume for the small pads.

Important Note: The suggested pad dimensions are for reference only. The final PCB land pattern should be modified based on specific manufacturing processes, thermal requirements, and individual design needs.

4.3 Polarity Identification

The cathode is typically indicated by a visual marker on the package, such as a notch, a flat edge, or a green marking on the base. The datasheet drawing clearly identifies the cathode side, which is essential for correct PCB orientation.

5. Soldering and Assembly Guidelines

5.1 Moisture Sensitivity and Storage

The device is moisture-sensitive. Precautions must be taken to prevent "popcorning" (package cracking due to rapid vapor expansion during reflow).

• Do not open the moisture-proof bag until ready for use.
• After opening, store at ≤30°C and ≤60% Relative Humidity (RH).
• Use within 168 hours (7 days) of opening the bag.
• If the storage time is exceeded or the desiccant indicates moisture ingress, bake the components at 60 ±5°C for 24 hours before use.

5.2 Reflow Soldering Process

The device is compatible with infrared and vapor phase reflow processes. A lead-free reflow temperature profile is suggested in the datasheet. Key parameters include preheat, soak, reflow peak temperature (not exceeding 260°C for ≤5 seconds), and cooling rates. Reflow soldering should not be performed more than two times to minimize thermal stress on the component.

5.3 Hand Soldering and Rework

If hand soldering is necessary, extreme care is required:

• Use a soldering iron with a tip temperature <350°C.
• Limit contact time to ≤3 seconds per terminal.Use an iron with a capacity of 25W or less.
• Allow an interval of ≥2 seconds between soldering each terminal to prevent heat buildup.
• Repair after initial soldering is discouraged. If unavoidable, use a dual-head soldering iron to simultaneously heat both terminals during removal to prevent mechanical stress on the solder joints and the LED itself. Always verify device functionality after any rework.

5.4 Circuit Board Handling

Avoid putting mechanical stress on the LED during heating (soldering) and do not warp the circuit board after soldering, as this can crack the component or its solder joints.

6. Packaging and Ordering Information

6.1 Tape and Reel Specifications

The device is supplied in industry-standard embossed carrier tape on 7-inch diameter reels. A detailed drawing of the carrier tape dimensions (pocket size, pitch, etc.) is provided. Each reel contains 1500 pieces.

6.2 Label Specification

The reel label includes standard information for traceability and manufacturing:

• CPN (Customer's Part Number)
• P/N (Manufacturer's Part Number: HIR26-21C/L289/TR8)
• QTY (Quantity)
• CAT (Ranks/Binning)
• HUE (Peak Wavelength)
• REF (Reference)
• LOT No. (Lot Number)
• MSL-X (Moisture Sensitivity Level)
• Made In (Country of Manufacture)

7. Application Suggestions

7.1 Typical Application Scenarios

• PCB-Mounted Infrared Sensors: Proximity sensing, object detection, line following in robotics.
• Infrared Remote Control Units: Ideal for applications requiring higher output power than standard remote control LEDs, potentially allowing for longer range or better performance in bright environments.
• Gas Counters/Meters: Often used in optical sensing mechanisms within utility meters.
• General Infrared Systems: Any embedded system requiring a compact, reliable IR source for data transmission, encoding, or sensing.

7.2 Design Considerations

• Current Limiting is Mandatory: As explicitly stated in the "Precautions," an external current-limiting resistor (or constant current driver) MUST be used in series with the LED. The forward voltage has a range, and a slight increase in supply voltage can cause a large, destructive increase in current if not properly limited.
• Thermal Management: Consider the power dissipation (P_d=V_F*I_F) and the maximum current derating with temperature. Ensure adequate PCB copper or other means to conduct heat away, especially in high-ambient-temperature or high-duty-cycle pulsed applications.
• Optical Design: The 25° viewing angle provides directionality. For broader coverage, secondary optics (diffusers) may be needed. For longer range, lenses can be used to collimate the beam.
• Driver Circuit: For pulsed operation at 1A, a transistor or MOSFET switch is required. Ensure the driver can handle the peak current and the required fast rise/fall times.

8. Technical Comparison and Differentiation

Compared to standard 5mm or 3mm through-hole infrared LEDs, the HIR26-21C/L289/TR8 offers significant advantages:

• Size: The 1.6mm SMD package enables miniaturization of end products and is compatible with high-speed pick-and-place assembly.
• Performance: The typical 17 mW/sr radiant intensity at 20mA is competitive, and the 85 mW/sr under pulsed conditions is a key feature for high-output needs.
• Reliability: The SMD construction and compatibility with standard reflow processes lead to more robust and consistent solder joints compared to hand-soldered through-hole parts.
• Compliance: The device is Pb-free, RoHS compliant, REACH compliant, and halogen-free (Br <900ppm, Cl <900ppm, Br+Cl <1500ppm), meeting stringent environmental regulations for global markets.

9. Frequently Asked Questions (Based on Technical Parameters)

9.1 Can I drive this LED directly from a 3.3V or 5V microcontroller pin?

No. The typical forward voltage is only 1.4V-1.6V. Connecting it directly to a 3.3V or 5V supply without a current-limiting resistor will almost certainly destroy the LED due to excessive current. Always use a series resistor calculated using Ohm's Law: R = (V_supply - V_F) / I_F.

9.2 What is the difference between the 20mA DC and 100mA pulsed ratings?

The 20mA rating is for continuous operation. The 100mA rating is for very short pulses (≤100μs) with a low duty cycle (≤1%). This allows the LED to be driven much harder for brief moments, producing a much brighter flash (85 mW/sr vs. 17 mW/sr) without overheating, as the average power remains low. This is perfect for remote controls.

9.3 How do I interpret the "View Angle" of 25 degrees?

This is the full angle at which the light intensity is half of its maximum (on-axis) value. Think of it as the width of the main "beam" or lobe of light. Light is still emitted outside this angle but at lower intensity. A 25° angle is moderately focused.

9.4 Why is moisture sensitivity and baking important?

Plastic SMD packages can absorb moisture from the air. During the high-temperature reflow soldering process, this moisture turns to steam rapidly, creating internal pressure that can crack the package or delaminate it from the chip ("popcorning"). Following the storage and baking guidelines prevents this failure mode.

10. Practical Design and Usage Case

Scenario: Designing a Long-Range Infrared Beacon

A designer needs a compact, battery-powered beacon that can be detected by a sensor 20 meters away in an indoor environment with some ambient IR noise.

1. Drive Method Selection: To maximize detection range, the designer chooses pulsed operation to leverage the high 85 mW/sr pulsed radiant intensity.
2. Circuit Design: A microcontroller GPIO pin controls an N-channel MOSFET. The LED is connected in series with a current-limiting resistor between the power supply (e.g., 3.3V) and the MOSFET drain. The resistor value is calculated for 100mA: R = (3.3V - 1.6V) / 0.1A = 17Ω (use 18Ω standard value). The microcontroller generates pulses of 100μs width with a 1% duty cycle (e.g., 100μs on, 9900μs off).
3. PCB Layout: The suggested pad layout is used as a starting point. Additional thermal relief and copper pour around the pads are added to aid heat dissipation during the high-current pulses.
4. Assembly: The components are placed on the PCB. The LED reel is stored properly, and the assembled board undergoes a single reflow pass using the recommended lead-free profile.
5. Optics (Optional): To further extend range, a simple plastic collimating lens could be placed over the LED to narrow the beam, concentrating the output power into a smaller area at the target distance.

This case demonstrates how the key datasheet parameters—pulsed radiant intensity, forward voltage, current ratings, and package size—directly inform a practical design.

11. Operating Principle

An Infrared Light Emitting Diode (IR LED) operates on the principle of electroluminescence in a semiconductor p-n junction. When a forward voltage is applied, electrons from the n-type material and holes from the p-type material are injected across the junction. When these charge carriers recombine, they release energy. In a GaAlAs diode like this one, the energy bandgap of the semiconductor material is engineered so that this released energy corresponds to a photon in the infrared spectrum, specifically around 850 nanometers. The water-clear epoxy package acts as a lens, shaping the emitted light into the specified radiation pattern (25° viewing angle).

12. Industry Trends and Developments

The market for subminiature infrared LEDs continues to evolve. Key trends relevant to devices like the HIR26-21C/L289/TR8 include:

• Increased Integration: Trends toward combining the IR emitter with a driver IC or even a photodetector in a single package for simpler sensor modules.
• Higher Efficiency: Ongoing material science research aims to improve the wall-plug efficiency (optical power out / electrical power in) of IR LEDs, leading to lower power consumption or higher output from the same size package.
• New Wavelengths: While 850nm and 940nm dominate, there is growing interest in other IR wavelengths for specific applications like gas sensing or enhanced eye safety.
• Advanced Packaging: Development of chip-scale packaging (CSP) and wafer-level packaging to further reduce size and cost while improving thermal performance.
• Application Expansion:
  • Biometrics and Security: Facial recognition, iris scanning.
  • Automotive: In-cabin occupancy sensing, driver monitoring systems.
  • Consumer Electronics: Proximity sensing for phones/tablets, gesture recognition.
  • Industrial IoT: Machine vision, condition monitoring.

Devices like the HIR26-21C/L289/TR8, with their small form factor, reliable performance, and compliance with environmental standards, are well-positioned to serve these expanding markets where compact, efficient infrared sources are a fundamental requirement.