5.0mm Infrared LED IR333-A Datasheet - T-1 3/4 Package - Peak Wavelength 940nm - Forward Voltage 1.5V - English Technical Document

1. Product Overview

The IR333-A is a high-intensity infrared (IR) emitting diode housed in a standard 5.0mm (T-1 3/4) blue plastic package. This device is engineered to emit light at a peak wavelength (λp) of 940 nanometers, which is optimally matched with common silicon-based photodetectors such as phototransistors, photodiodes, and infrared receiver modules. Its primary function is to serve as a reliable infrared light source in various sensing and transmission systems.

1.1 Core Advantages and Target Market

The IR333-A offers several key advantages that make it suitable for industrial and consumer applications. It features high radiant intensity, ensuring strong signal transmission. It operates with a low forward voltage, contributing to energy efficiency. The device is designed with environmental compliance in mind, being Pb-free, compliant with EU REACH regulations, and meeting halogen-free standards (Br < 900ppm, Cl < 900ppm, Br+Cl < 1500ppm). Its 2.54mm lead spacing makes it compatible with standard breadboards and PCBs. The target markets include industrial automation, consumer electronics, safety systems, and data communication interfaces where reliable infrared signaling is required.

2. In-Depth Technical Parameter Analysis

This section provides a detailed, objective interpretation of the electrical, optical, and thermal characteristics specified in the datasheet.

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. They are not intended for normal operation.

• Continuous Forward Current (IF): 100 mA. This is the maximum DC current that can be applied continuously without degrading the LED's performance or lifespan.
• Peak Forward Current (IFP): 1.0 A. This high current is permissible only under pulsed conditions with a pulse width ≤ 100μs and a duty cycle ≤ 1%. This allows for very brief, high-intensity bursts of light, useful for certain sensing or communication protocols.
• Reverse Voltage (VR): 5 V. The maximum voltage that can be applied in the reverse direction across the LED. Exceeding this can cause breakdown.
• Operating Temperature (Topr): -40°C to +85°C. The ambient temperature range within which the device is guaranteed to operate according to its specifications.
• Storage Temperature (Tstg): -40°C to +100°C. The temperature range for storing the device when not in operation.
• Soldering Temperature (Tsol): 260°C for a maximum of 10 seconds. This defines the reflow soldering profile limits to prevent package damage.
• Power Dissipation (Pd): 150 mW at or below 25°C free air temperature. This is the maximum power the package can dissipate as heat.

2.2 Electro-Optical Characteristics

These parameters, measured at a standard test condition of Ta=25°C, define the device's performance under normal operating conditions.

• Radiant Intensity (Ie): This is the optical power emitted per unit solid angle (steradian). At a standard drive current of 20mA, the typical value is 20 mW/sr, with a minimum of 7.8 mW/sr and a maximum of 48 mW/sr. Under pulsed conditions (100mA, duty ≤1%), the typical intensity rises to 85 mW/sr, and at the peak pulsed current of 1A, it can reach 750 mW/sr. This demonstrates the device's capability for high-output applications when driven with pulses.
• Peak Wavelength (λp): 940 nm (typical). This is the wavelength at which the LED emits the most optical power. It is well-suited for use with silicon detectors, which have good sensitivity in the near-infrared region.
• Spectral Bandwidth (Δλ): 45 nm (typical). This indicates the range of wavelengths emitted, centered around the peak. A narrower bandwidth can be beneficial for filtering out ambient light noise.
• Forward Voltage (VF): At 20mA, the typical forward voltage is 1.5V (min 1.2V, max not specified for 20mA in the table, but implied by other conditions). This relatively low voltage contributes to lower power consumption. The voltage increases with current, as shown by the 1.4V (typ) at 100mA pulsed and 2.6V (typ) at 1A pulsed.
• Reverse Current (IR): Maximum of 10 μA at VR=5V. This is the small leakage current that flows when the device is reverse-biased.
• Viewing Angle (2θ1/2): 20 degrees (typical). This is the full angle at which the radiant intensity drops to half of its maximum value (on-axis). A 20-degree angle indicates a moderately focused beam, useful for directed sensing applications.

3. Binning System Explanation

The datasheet includes a binning table for Radiant Intensity, which is a common practice to categorize LEDs based on measured performance.

3.1 Radiant Intensity Binning

LEDs are sorted into different "bins" or ranks (M, N, P, Q, R) based on their measured radiant intensity at IF=20mA. This allows designers to select parts with a guaranteed minimum performance level for their application. For example, selecting a "Q" bin part guarantees a radiant intensity between 21.0 and 34.0 mW/sr. This system ensures consistency in production runs. The datasheet does not indicate binning for peak wavelength or forward voltage for this specific part number, suggesting tight control or a single specification for those parameters.

4. Performance Curve Analysis

The typical characteristic curves provide valuable insight into how the LED behaves under varying conditions. While the specific graphical data points are not provided in the text, the curves referenced allow for the following analysis.

4.1 Forward Current vs. Ambient Temperature (Fig.1)

This curve would typically show the derating of the maximum allowable forward current as the ambient temperature increases. To prevent overheating and ensure reliability, the continuous forward current must be reduced when operating above 25°C. The absolute maximum power dissipation of 150mW is the limiting factor.

4.2 Spectral Distribution (Fig.2)

This plot visualizes the relative optical power output as a function of wavelength. It would show a bell-shaped curve centered at 940 nm with the 45 nm spectral bandwidth. This helps in understanding the purity of the infrared light and its match with detector spectral response.

4.3 Peak Emission Wavelength vs. Temperature (Fig.3)

The peak wavelength of an LED has a temperature coefficient, typically shifting to longer wavelengths (red shift) as the junction temperature increases. This curve quantifies that shift for the IR333-A, which is important for applications requiring precise wavelength matching.

4.4 Forward Current vs. Forward Voltage (IV Curve) (Fig.4)

This fundamental curve shows the exponential relationship between the voltage applied across the LED and the resulting current. It is crucial for designing the current-limiting driver circuit. The curve will show the typical "knee" voltage (around 1.2-1.5V) and how the voltage rises with increasing current.

4.5 Radiant Intensity vs. Forward Current (Fig.5)

This curve demonstrates the sub-linear relationship between drive current and light output. While intensity increases with current, the efficiency (light output per unit of electrical input) typically decreases at very high currents due to increased heat generation. The data from the table (20mA -> 20 mW/sr typ, 100mA pulsed -> 85 mW/sr typ) suggests this relationship.

4.6 Relative Radiant Intensity vs. Angular Displacement (Fig.6)

This is the spatial radiation pattern of the LED. It plots the normalized intensity as a function of the angle from the central axis. For a 5mm LED with a dome lens, this pattern is typically Lambertian or near-Lambertian. The specified 20-degree viewing angle (2θ1/2) is a key data point from this curve, defining the beam's width.

5. Mechanical and Package Information

5.1 Package Dimensions

The IR333-A uses the industry-standard T-1 3/4 (5.0mm diameter) package. The lead spacing is 2.54mm (0.1 inches), which is the standard pitch for through-hole components on printed circuit boards. The package material is blue plastic, which may act as a visible light filter to some extent, helping to block ambient visible light from reaching the chip and potentially reducing noise in the detector. The cathode is typically identified by a flat spot on the package rim and/or a shorter lead. Designers must consult the detailed package drawing (implied by the "Package Dimensions" section) for exact dimensions and tolerances (±0.25mm unless otherwise specified).

6. Soldering and Assembly Guidelines

The absolute maximum rating for soldering temperature is 260°C for a duration not exceeding 10 seconds. This is a typical rating for lead-free reflow soldering processes. For hand soldering, a temperature-controlled iron should be used, and contact time should be minimized to prevent thermal damage to the plastic package and the internal wire bonds. Standard ESD (Electrostatic Discharge) precautions should be observed during handling and assembly, as LEDs are sensitive semiconductor devices. Storage should be within the specified temperature range of -40°C to +100°C in a dry environment.

7. Packaging and Ordering Information

The standard packing specification is as follows: 200 to 500 pieces are packed in one bag. Five bags are then placed into one box. Finally, ten boxes are packed into one master carton. The label on the packaging includes critical information for traceability and identification: Customer's Production Number (CPN), Production Number (P/N), Packing Quantity (QTY), Ranks (CAT, referring to the intensity bin), Peak Wavelength (HUE), a Reference code, and the Lot Number (LOT No) which includes a code for the month of manufacture.

8. Application Recommendations

8.1 Typical Application Scenarios

• Free Air Transmission Systems: Used in remote controls, short-range data links, or proximity sensors where an infrared signal is transmitted through the air.
• Optoelectronic Switches & Object Detection: Paired with a phototransistor or photodiode to create a break-beam sensor for counting, position sensing, or limit switches.
• Floppy Disk Drive: Historically used to detect the presence of a write-protect tab or disk-in-place.
• Smoke Detectors: Employed in obscuration-type smoke detectors, where smoke particles scatter a beam of infrared light between an LED and a detector.
• General Infrared Applied Systems: Any embedded system requiring a dependable, modulated, or continuous IR light source.

8.2 Design Considerations

• Current Limiting: An LED is a current-driven device. A series resistor or constant current driver circuit is mandatory to limit the forward current to a safe value (e.g., 20mA for continuous operation). The resistor value can be calculated using Ohm's Law: R = (Vsupply - VF) / IF.
• Heat Management: While the power dissipation is low, operating at high ambient temperatures or near maximum current will generate heat. Ensure adequate ventilation or derate the operating current as shown in the derating curve.
• Optical Alignment: For maximum signal strength in a paired emitter-detector system, precise mechanical alignment is crucial, especially with a 20-degree viewing angle.
• Ambient Light Rejection: In environments with strong ambient IR (e.g., sunlight), modulating the LED drive signal and using a detector circuit tuned to that modulation frequency can dramatically improve signal-to-noise ratio.
• Reverse Voltage Protection: Although the device can tolerate up to 5V in reverse, it is good practice to avoid reverse biasing. In AC or bipolar circuits, a protection diode in parallel (cathode to anode) may be necessary.

9. Technical Comparison and Differentiation

Compared to generic 5mm IR LEDs, the IR333-A's key differentiators are its clearly specified high radiant intensity (up to 48 mW/sr min for the R bin) and its comprehensive environmental compliance (RoHS, REACH, Halogen-Free). The detailed binning system provides guaranteed performance levels, which is essential for design consistency in volume production. The 940nm wavelength is one of the most common and versatile, offering a good balance between detector sensitivity and lower absorption in the atmosphere compared to longer wavelengths. Its low forward voltage can lead to slightly lower power consumption in battery-operated devices compared to LEDs with higher Vf.

10. Frequently Asked Questions (Based on Technical Parameters)

1. Q: Can I drive this LED directly from a 5V microcontroller pin? A: No. A microcontroller pin typically cannot source 20mA safely, and more importantly, there is no current limiting. You must use a transistor as a switch and a series resistor to limit the current to the desired value (e.g., 20mA). Calculate the resistor as R = (5V - 1.5V) / 0.02A = 175Ω. Use the nearest standard value (e.g., 180Ω).
2. Q: What is the difference between continuous and pulsed operation? A: Continuous operation (DC) generates constant heat. Pulsed operation (with low duty cycle) allows much higher instantaneous current (up to 1A) because the LED has time to cool between pulses, preventing thermal overload. This yields much higher peak optical output.
3. Q: How do I identify the cathode? A: For this package, look for a flat spot on the plastic rim of the LED. The lead nearest to this flat is the cathode. Additionally, the cathode lead is often shorter than the anode lead.
4. Q: Is a heat sink required? A: For continuous operation at 20mA (approx. 30mW of power dissipation), a heat sink is generally not required. If operating near the maximum current (100mA DC) or in high ambient temperatures, consider the thermal derating and potentially provide some board-level cooling.
5. Q: Why is the package blue? A: The blue plastic acts as a filter that blocks some visible light, making the package appear dark. This helps to reduce the amount of ambient visible light that can enter the package and reach the IR-emitting chip, which could otherwise cause interference in the detecting circuit.

11. Practical Use Case Example

Designing a Simple Object Detection Sensor: A common application is a break-beam sensor. Place the IR333-A on one side and a phototransistor (e.g., tuned to 940nm) on the other, aligned on the same axis. Drive the LED with a 180Ω resistor from a 5V supply, resulting in approximately 20mA of current. When an object passes between them, it interrupts the infrared beam. The phototransistor's collector-emitter resistance will change dramatically. This change can be converted into a voltage signal using a pull-up resistor and fed into a comparator or microcontroller ADC pin to detect the object's presence. To combat ambient light, you could pulse the LED at a specific frequency (e.g., 1kHz) and use a band-pass filter or synchronous detection in the receiver circuit.

12. Principle of Operation

An Infrared Light Emitting Diode (IR LED) is a semiconductor p-n junction diode. When forward-biased (positive voltage applied to the anode relative to the cathode), electrons from the n-type region and holes from the p-type region are injected into the junction region. When these charge carriers recombine, they release energy. In an IR LED, this energy is released primarily in the form of photons (light particles) in the infrared spectrum. The specific wavelength (940nm in this case) is determined by the bandgap energy of the semiconductor materials used (Gallium Aluminum Arsenide - GaAlAs, as indicated in the Device Selection Guide). The plastic package encapsulates the chip, provides mechanical protection, and incorporates a lens that shapes the emitted light into the specified viewing angle pattern.

13. Technology Trends

Infrared LED technology continues to evolve. General trends in the industry include the development of devices with even higher radiant intensity and wall-plug efficiency (optical power out / electrical power in). There is also a push towards miniaturization, with surface-mount device (SMD) packages becoming more prevalent than through-hole packages like the T-1 3/4 for space-constrained applications. The demand for specific, narrow wavelength bands is growing for specialized applications like gas sensing or biomedical monitoring. Furthermore, integration is a key trend, with combined emitter-detector pairs in single packages or LEDs with built-in drivers becoming available to simplify circuit design and reduce footprint.