Infrared Emitter LED 940nm Datasheet - EIA Package - Peak Wavelength 940nm - Forward Voltage 1.2V - Radiant Intensity 0.8mW/sr - English Technical Document

1. Product Overview

This document details the specifications for a discrete infrared emitter component. The device is designed for applications requiring reliable infrared emission, such as in remote control systems, IR wireless data transmission, and security alarm systems. It belongs to a product line that includes various infrared emitting diodes (IREDs) and photodetectors. The primary material used is Gallium Arsenide (GaAs), which is optimized for emission at a peak wavelength of 940 nanometers. This wavelength is commonly used in consumer electronics as it is invisible to the human eye and offers good performance with silicon-based receivers.

The component is offered in a standard EIA package, making it compatible with automated assembly processes. It features a top-view, water-clear flat lens that provides a wide viewing angle. The product is compliant with RoHS directives and is classified as a green product.

1.1 Key Features

• Compliant with RoHS, Green Product standards.
• Top view design with a water-clear flat lens.
• Packaged in 8mm tape on 7-inch diameter reels for automated placement.
• Compatible with automatic placement equipment.
• Suitable for infrared reflow soldering processes.
• Standard EIA package footprint.
• Peak emission wavelength (λp) of 940nm.
• Moisture Sensitivity Level (MSL): Level 3.

1.2 Target Applications

• Primary use as an infrared emitter source.
• Integration into PCB-mounted infrared sensor assemblies.
• Remote control units for consumer electronics (TVs, audio systems).
• Short-range wireless data links.
• Proximity sensors and object detection.
• Security and alarm system beam breaks.

2. Technical Parameters: In-Depth Objective Interpretation

The following sections provide a detailed analysis of the device's key performance parameters as defined in the datasheet. Understanding these parameters is critical for proper circuit design and reliable operation.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed and should be avoided for reliable long-term performance.

• Power Dissipation (Pd): 100 mW. This is the maximum total power the device can dissipate as heat. Exceeding this limit risks thermal runaway and failure.
• Peak Forward Current (I_FP): 500 mA. This is the maximum allowable current under pulsed conditions (300 pulses per second, 10 μs pulse width). It is significantly higher than the DC rating, allowing for high-brightness pulses in remote controls.
• DC Forward Current (I_F): 50 mA. The maximum continuous forward current. For most efficient and reliable operation, a lower drive current (e.g., 20mA as used in test conditions) is recommended.
• Reverse Voltage (V_R): 5 V. The maximum voltage that can be applied in the reverse direction. The device is not designed for reverse operation, and exceeding this can cause breakdown.
• Operating & Storage Temperature: -40°C to +85°C and -55°C to +100°C, respectively. These ranges define the environmental conditions for operation and non-operation.
• Infrared Soldering Condition: Withstands 260°C for a maximum of 10 seconds. This is critical for defining the reflow soldering profile.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters measured at an ambient temperature (T_A) of 25°C. They define the device's behavior under normal operating conditions.

• Radiant Intensity (I_E): 0.8 mW/sr (Typical) at I_F = 20mA. This measures the optical power emitted per unit solid angle. The minimum is 0.42 mW/sr, and testing tolerance is ±15%. This parameter directly impacts the effective range of the IR system.
• Peak Emission Wavelength (λ_Peak): 940 nm (Typical). This is the wavelength at which the emitted optical power is maximum. It must be matched with the peak sensitivity of the receiving photodiode or phototransistor.
• Spectral Line Half-Width (Δλ): 50 nm (Typical). This indicates the spectral bandwidth where the emission intensity is at least half of the peak value. A narrower bandwidth can be beneficial for filtering out ambient light noise.
• Forward Voltage (V_F): 1.2 V (Typical), 1.6 V (Max) at I_F = 20mA. This is the voltage drop across the diode when conducting. It is essential for calculating the series resistor value: R_series = (V_supply - V_F) / I_F.
• Reverse Current (I_R): 10 μA (Max) at V_R = 5V. This is the small leakage current when the diode is reverse-biased.
• Viewing Angle (2θ_1/2): 150° (Typical). This is the full angle at which the radiant intensity falls to half of its on-axis value. A wide angle like this is useful for applications requiring broad coverage rather than a focused beam.

3. Performance Curve Analysis

The datasheet provides several characteristic curves that illustrate how key parameters vary with operating conditions. These are invaluable for design optimization.

3.1 Spectral Distribution

The spectral distribution curve (Fig. 1) shows the relative radiant intensity as a function of wavelength. It confirms the peak at 940nm and the approximately 50nm half-width, providing a visual representation of the emitted light's spectral purity.

3.2 Forward Current vs. Ambient Temperature & Forward Voltage

Figure 2 shows how the maximum allowable forward current derates as ambient temperature increases. This is crucial for thermal management. Figure 3 is the standard I-V (Current-Voltage) curve, showing the exponential relationship between forward current and voltage. The curve helps in understanding the dynamic resistance of the diode.

3.3 Relative Radiant Intensity vs. Temperature & Current

Figure 4 illustrates how the optical output power decreases as the ambient temperature rises. Figure 5 shows how the output power increases with forward current, but not linearly. It highlights the point of diminishing returns and potential efficiency drop at very high currents.

3.4 Radiation Pattern

The polar radiation diagram (Fig. 6) graphically represents the viewing angle. The nearly circular pattern with intensity values marked at different angles confirms the very wide, Lambertian-like emission pattern characteristic of a flat-lens package.

4. Mechanical & Packaging Information

4.1 Outline Dimensions

The datasheet includes a detailed mechanical drawing of the component. Key dimensions include the body size, lead spacing, and overall height. All dimensions are in millimeters with a standard tolerance of ±0.1mm unless otherwise specified. The package conforms to a standard EIA footprint, ensuring compatibility with common PCB layouts and pick-and-place machines.

4.2 Suggested Soldering Pad Dimensions

A recommended land pattern (footprint) for PCB design is provided. Adhering to these dimensions ensures proper solder joint formation during reflow. The recommendation includes using a metal stencil for solder paste application with a thickness of 0.1mm (4 mils) or 0.12mm (5 mils).

4.3 Polarity Identification

The cathode is typically indicated by a flat side, notch, or shorter lead on the component body and in the outline drawing. Correct polarity must be observed during assembly to prevent device damage.

4.4 Tape and Reel Packaging Dimensions

The component is supplied in embossed carrier tape on 7-inch (178mm) diameter reels. The datasheet provides detailed dimensions of the tape pockets, cover tape, and reel hub. Standard reel quantities are 5000 pieces per reel. The packaging complies with ANSI/EIA-481-1-A-1994 specifications.

5. Soldering & Assembly Guidelines

5.1 Reflow Soldering Parameters

The device is compatible with infrared (IR) reflow soldering processes. A suggested profile for lead-free (Pb-free) solder is provided, with key parameters including:

• Pre-heat: 150–200°C.
• Pre-heat Time: Maximum 120 seconds.
• Peak Temperature: Maximum 260°C.
• Time Above Liquidus: Maximum 10 seconds (recommended max two reflow cycles).

The profile is based on JEDEC standards. It is emphasized that the optimal profile depends on the specific board design, components, solder paste, and oven, so characterization is necessary.

5.2 Hand Soldering

If hand soldering is necessary, use a soldering iron with a temperature not exceeding 300°C, and limit the contact time to a maximum of 3 seconds per lead.

5.3 Storage Conditions

Due to its Moisture Sensitivity Level (MSL) 3 rating:

• Sealed Bag: Store at ≤30°C and ≤90% RH. Use within one year of the bag seal date.
• After Bag Opening: Store at ≤30°C and ≤60% RH. It is recommended to complete IR reflow within one week (168 hours).
• Extended Storage (Opened): Store in a sealed container with desiccant or in a nitrogen desiccator.
• Baking: If exposed for more than one week, bake at approximately 60°C for at least 20 hours before soldering to remove absorbed moisture and prevent \"popcorning\" during reflow.

5.4 Cleaning

If post-solder cleaning is required, use alcohol-based solvents such as isopropyl alcohol. Avoid aggressive or unknown chemical cleaners that may damage the epoxy lens or package.

6. Application Suggestions & Design Considerations

6.1 Typical Application Circuits

The most common circuit is a simple series connection: a voltage source (V_CC), a current-limiting resistor (R_S), and the IRED. R_S = (V_CC - V_F) / I_F. For pulsed operation (e.g., remote control), a transistor (BJT or MOSFET) is typically used to switch the IRED on and off at the desired frequency and duty cycle. The peak current must not exceed the I_FP rating.

6.2 Optical Design Considerations

• Range vs. Current: The effective range is proportional to the square root of the radiant intensity. Doubling the drive current does not double the range.
• Lens Selection: The built-in flat lens provides wide coverage. For longer range or focused beams, an external plastic lens may be added to collimate the light.
• Receiver Matching: Always pair the 940nm emitter with a photodetector (photodiode, phototransistor, or IC) whose peak sensitivity is also in the 940nm region. Many silicon detectors have good sensitivity around 850-950nm.
• Ambient Light Rejection: In environments with strong ambient IR (sunlight, incandescent bulbs), use a modulated signal and a receiver with a matching demodulator. An optical filter on the receiver that blocks visible light and passes 940nm can significantly improve the signal-to-noise ratio.

6.3 Thermal Management

While the device can handle 100mW, operating at lower power dissipation increases reliability and longevity. Ensure adequate PCB copper area around the pads to act as a heat sink, especially if driving near the maximum DC current. The derating curve (Fig. 2) must be consulted for high-temperature environments.

7. Technical Comparison & Differentiation

This 940nm GaAs IRED offers a balanced set of characteristics for general-purpose infrared applications. Key differentiators implied by its specifications include:

• Wavelength: 940nm is preferred over 850nm in many consumer applications because it is less visible as a faint red glow, providing a more discreet operation.
• Wide Viewing Angle: The 150° angle is exceptionally broad, suitable for applications where alignment is not critical or wide area coverage is needed (e.g., occupancy sensors).
• Standard Package: The EIA package ensures easy sourcing, compatibility, and replacement within the industry.
• Robustness: The ratings for pulsed current (500mA) and reflow soldering (260°C) indicate a component designed for high-volume, reliable manufacturing.

8. Frequently Asked Questions (Based on Technical Parameters)

8.1 What resistor value should I use to drive this IRED at 20mA from a 5V supply?

Using the typical V_F of 1.2V: R = (5V - 1.2V) / 0.020A = 190 Ohms. A standard 180 or 200 Ohm resistor would be suitable. Always use the maximum V_F (1.6V) for a conservative design to ensure current doesn't exceed the target: R_min = (5V - 1.6V) / 0.020A = 170 Ohms.

8.2 Can I use this for a long-range remote control?

Its radiant intensity of 0.8 mW/sr is suitable for typical indoor remote controls over distances of 5-10 meters. For longer range, you would need to increase the drive current (within pulsed ratings), use a focusing lens, or select an IRED with a higher radiant intensity specification.

8.3 The datasheet says \"Reverse voltage condition is applied for IR test only. The device is not designed for reverse operation.\" What does this mean?

This means the 5V reverse voltage rating is a test parameter to verify leakage current during manufacturing. It is not an operational rating. In your circuit, you must ensure the IRED is never subjected to a reverse bias during normal operation, as even a small reverse voltage could damage it if not current-limited. Always include protection, such as ensuring it is correctly oriented or adding a parallel diode if the circuit topology could cause reverse voltage.

8.4 How critical is the one-week floor life after opening the moisture barrier bag?

For MSL 3 components, it is very important. Exceeding the floor life without proper storage or baking risks moisture ingress into the plastic package. During the high-temperature reflow soldering process, this moisture can vaporize rapidly, causing internal delamination, cracks, or \"popcorning,\" which leads to immediate or latent failure. Adhere strictly to the storage and baking guidelines.

9. Operational Principles

An Infrared Emitting Diode (IRED) operates on the same principle as a standard visible-light LED but uses semiconductor materials (like GaAs) with a bandgap corresponding to infrared photon energies. When a forward voltage is applied, electrons and holes recombine in the active region of the semiconductor, releasing energy in the form of photons. For GaAs, this photon energy corresponds to a wavelength around 940nm. The water-clear epoxy lens is transparent to both visible and infrared light, allowing the IR radiation to pass through while also providing mechanical and environmental protection for the semiconductor chip.

10. Industry Trends

The market for discrete infrared components remains stable, driven by established applications like remote controls and evolving uses in IoT sensors, gesture recognition, and machine vision. Trends include the integration of emitters and detectors into smaller, more robust packages, the development of higher-speed IREDs for data communication (IrDA successors), and increased emphasis on power efficiency and reliability for battery-operated devices. The move towards lead-free (Pb-free) and halogen-free materials in compliance with global environmental regulations is also a standard requirement, which this component meets.