Infrared Emitter LED 850nm SMD Datasheet - Peak Wavelength 850nm - Forward Voltage 1.4V - Radiant Intensity 20mW/sr - English Technical Document

1. Product Overview

This document details the specifications for a discrete infrared emitter component designed for surface-mount technology (SMT) applications. The device is an 850nm infrared emitting diode (IRED) constructed with an AlGaAs material system, encapsulated in a standard EIA package with a black dome lens for controlled light distribution. It is engineered to provide reliable performance in automated assembly environments.

The core function of this component is to efficiently convert electrical current into infrared light at a peak wavelength of 850 nanometers. This wavelength is commonly used in applications where visible light emission is undesirable, or where compatibility with silicon-based photodetectors (which have high sensitivity around 850-940nm) is required. The product is compliant with RoHS directives and is classified as a green product.

1.1 Key Features and Applications

The infrared emitter is characterized by several key features that make it suitable for modern electronic manufacturing:

• Compatibility with infrared reflow soldering processes, essential for high-volume PCB assembly.
• Packaged in 8mm tape on 7-inch diameter reels for use with automatic pick-and-place equipment.
• Features a top-view design with a black dome lens, providing a typical viewing angle (2θ1/2) of 20 degrees for directed emission.
• Peak emission wavelength (λp) is specified at 850nm.

Primary Application Areas: The component is primarily intended for use as an infrared emitter in systems requiring non-visible light communication or sensing. Typical applications include, but are not limited to, remote control units for consumer electronics, short-range infrared wireless data transmission links, and PCB-mounted infrared sensor systems such as proximity sensors or interrupters.

2. Absolute Maximum Ratings

Operating the device beyond these limits may cause permanent damage. All ratings are specified at an ambient temperature (TA) of 25°C.

• Power Dissipation (PD): 100 mW
• Peak Forward Current (IFP): 800 mA (under pulsed conditions: 300 pulses per second, 10μs pulse width)
• DC Forward Current (IF): 60 mA
• Reverse Voltage (VR): 5 V
• Operating Temperature Range (Topr): -40°C to +85°C
• Storage Temperature Range (Tstg): -55°C to +100°C
• Infrared Reflow Soldering: Maximum peak temperature of 260°C for 10 seconds is allowed.

These ratings define the operational boundaries for reliable device lifetime. Exceeding the DC forward current or power dissipation will generate excessive heat, potentially leading to accelerated degradation of the semiconductor junction. The reverse voltage rating is critical for protecting the LED from electrostatic discharge (ESD) or incorrect polarity connection in a circuit.

3. Electrical and Optical Characteristics

The following parameters are guaranteed at an ambient temperature of 25°C under the specified test conditions. These values represent the typical performance expected from the device.

• Radiant Intensity (I_E): 20 mW/sr (Typical) at a forward current (I_F) of 20mA. The test tolerance for this measurement is ±15%.
• Peak Emission Wavelength (λ_Peak): 850 nm (Typical) at I_F = 20mA.
• Spectral Line Half-Width (Δλ): 50 nm (Typical) at I_F = 20mA. This indicates the spectral bandwidth where the radiant intensity is at least half of its peak value.
• Forward Voltage (V_F): 1.4 V (Typical), with a maximum of 1.7 V at I_F = 20mA.
• Reverse Current (I_R): 10 μA (Maximum) at a reverse voltage (V_R) of 5V.
• Viewing Angle (2θ_1/2): 20 degrees (Typical). θ_1/2 is defined as the off-axis angle where the radiant intensity drops to half of its value on the optical axis (0 degrees).

The forward voltage is a crucial parameter for circuit design, as it determines the voltage drop across the LED and is necessary for calculating the current-limiting resistor value. The 20-degree viewing angle signifies a relatively narrow beam, which is beneficial for applications requiring directed illumination over a specific area or distance.

4. Performance Curve Analysis

The datasheet provides several characteristic curves that illustrate device behavior under varying conditions. Understanding these curves is vital for robust system design.

4.1 Spectral Distribution

The spectral distribution curve shows the relative radiant intensity as a function of wavelength. For this 850nm emitter, the output is centered around 850nm with a typical half-width of 50nm. This characteristic is important for matching the emitter to the spectral sensitivity of the receiving photodetector (e.g., silicon PIN photodiode or phototransistor) to maximize signal-to-noise ratio.

4.2 Forward Current vs. Ambient Temperature

This derating curve shows the maximum allowable DC forward current decreasing as the ambient temperature increases. At the maximum operating temperature of +85°C, the permissible continuous current is significantly lower than the 60mA rating at 25°C. Designers must use this curve to ensure the LED is not overdriven in high-temperature environments.

4.3 Forward Current vs. Forward Voltage (IV Curve)

The IV curve depicts the non-linear relationship between the applied forward voltage and the resulting current through the LED. The typical forward voltage of 1.4V at 20mA is shown on this curve. The exponential nature of the curve highlights why LEDs must be driven by a current source or with a series current-limiting resistor, as a small change in voltage can cause a large change in current.

4.4 Relative Radiant Intensity vs. Forward Current

This curve demonstrates that the light output (radiant intensity) is approximately proportional to the forward current in its normal operating range. It is not perfectly linear due to heating and other efficiency factors, but it confirms that controlling current is the primary method for controlling light output.

4.5 Relative Radiant Intensity vs. Ambient Temperature

The output power of an LED decreases as its junction temperature rises. This curve quantifies that relationship, showing the relative radiant intensity dropping as ambient temperature increases, even if the drive current is held constant. This thermal derating must be accounted for in applications requiring stable output over a wide temperature range.

4.6 Radiation Pattern (Polar Diagram)

The polar diagram graphically represents the viewing angle. The normalized intensity is plotted against the angle from the central axis. The diagram for this device confirms the 20-degree half-angle, showing a beam pattern that is strongest in the center and falls off symmetrically.

5. Mechanical and Package Information

5.1 Outline Dimensions

The device conforms to a standard EIA surface-mount package outline. Key dimensions include the body size, lead spacing, and overall height. All dimensions are provided in millimeters with a typical tolerance of ±0.1mm unless otherwise specified. The package features a black epoxy body with a dome lens.

5.2 Suggested Soldering Pad Layout

A recommended land pattern (footprint) for PCB design is provided to ensure reliable solder joint formation during reflow. The dimensions are 1.8mm in length and 1.0mm in width for the primary pad areas, with a 1.0mm gap between them. It is advised to use a metal stencil for solder paste application with a thickness of 0.1mm (4 mils) or 0.12mm (5 mils).

5.3 Tape and Reel Packaging Dimensions

The components are supplied in embossed carrier tape on 7-inch (178mm) diameter reels. The tape width is 8mm. Each reel contains 2000 pieces. The packaging conforms to ANSI/EIA 481-1-A-1994 specifications. The tape is sealed with a cover tape, and the maximum allowed number of consecutive missing components in a reel is two.

6. Assembly, Handling, and Application Guidelines

6.1 Soldering and Reflow Profile

The device is compatible with infrared (IR) reflow soldering processes, which is the standard for SMT assembly. A JEDEC-compliant reflow profile for lead-free (Pb-free) solder is recommended. Key parameters of this profile include: a pre-heat stage at 150-200°C for up to 120 seconds, followed by a temperature ramp to a peak of 260°C maximum. The time above 245°C should be controlled, and the total time at the peak temperature of 260°C must not exceed 10 seconds. It is critical to follow solder paste manufacturer recommendations and perform board-level characterization, as the ideal profile can vary based on the specific PCB assembly.

For manual rework with a soldering iron, the tip temperature should not exceed 300°C, and contact time should be limited to 3 seconds per solder joint.

6.2 Storage and Moisture Sensitivity

When the original moisture-proof barrier bag (with desiccant) is sealed, the components should be stored at 30°C or less and 90% relative humidity (RH) or less. The shelf life under these conditions is one year. Once the barrier bag is opened, the components are exposed to ambient humidity. For extended storage outside the original packaging (more than one week), it is strongly recommended to store them in a sealed container with desiccant or in a nitrogen-purged desiccator. If components have been exposed to ambient conditions for over one week, a baking procedure (approximately 60°C for at least 20 hours) is required before reflow soldering to remove absorbed moisture and prevent \"popcorning\" damage during reflow.

6.3 Cleaning

If post-solder cleaning is necessary, only alcohol-based solvents such as isopropyl alcohol (IPA) should be used. Harsh or aggressive chemical cleaners may damage the epoxy lens or package.

6.4 Drive Circuit Design

An LED is a current-operated device. To ensure consistent light output and prevent damage, it must be driven by a controlled current source. The simplest and most common method is to use a series current-limiting resistor. The resistor value (R_series) can be calculated using Ohm's Law: R_series = (V_supply - V_F) / I_F, where V_F is the forward voltage of the LED at the desired current I_F. When multiple LEDs are connected in parallel, it is highly recommended to use a separate current-limiting resistor for each LED (as shown in \"Circuit A\" in the original document) to prevent current hogging and ensure uniform brightness, as the forward voltage can vary slightly from device to device.

6.5 Application Considerations and Cautions

This product is designed for use in standard commercial and industrial electronic equipment, including office equipment, communication devices, and household appliances. For applications requiring exceptional reliability where failure could jeopardize life or health (e.g., aviation, medical systems, critical safety devices), specific qualification and consultation with the component manufacturer are essential prior to design-in. Designers should always operate the device within its Absolute Maximum Ratings and recommended operating conditions, considering the worst-case environmental scenarios for their application.