IR Emitter and Detector LTE-R38386AS-ZF Datasheet - 850nm Wavelength - 1A Forward Current - 3.6V Max Voltage - 3.6W Power Dissipation - English Technical Document

1. Product Overview

This document provides the complete technical specifications for a discrete infrared component designed for applications requiring high power, high speed, and wide viewing angles. The device is an infrared emitter operating at a peak wavelength of 850nm, fabricated using AlGaAs technology for high-speed performance. It is part of a broader product line that includes various infrared emitters and detectors such as GaAs 940nm IREDs, PIN Photodiodes, and Phototransistors. The component is engineered to meet RoHS compliance and is classified as a Green Product.

1.1 Core Advantages and Target Market

The primary advantages of this component include a high-power LED light source, high performance with long operational life, and the capability to handle high driving currents. These features make it suitable for demanding infrared applications. The target markets and applications are primarily in consumer and industrial electronics, specifically where reliable infrared signaling is required.

2. In-Depth Technical Parameter Analysis

This section provides a detailed, objective interpretation of the device's key electrical, optical, and thermal parameters as specified under standard test conditions (TA=25°C).

2.1 Absolute Maximum Ratings

The device is designed to operate within strict limits to ensure reliability and prevent damage. The maximum power dissipation is 3.6 Watts. It can handle a peak forward current of 5 Amperes under pulsed conditions (300 pulses per second, 10μs pulse width) and a continuous DC forward current of 1 Ampere. The maximum allowable reverse voltage is 5 Volts. The thermal resistance from the junction is specified at 9 K/W, which is critical for thermal management design. The operational temperature range is from -40°C to +85°C, and the storage temperature range is from -55°C to +100°C. The component can withstand infrared soldering at 260°C for a maximum of 10 seconds.

2.2 Electrical and Optical Characteristics

Under a test condition of 1A forward current (IF), the device exhibits a radiant intensity (IE) with a typical value of 320 mW/sr and a minimum of 200 mW/sr. The total radiant flux (Фe) is typically 1270 mW. The peak emission wavelength (λPeak) is 850 nm, with a spectral line half-width (Δλ) of 50 nm, defining its optical bandwidth. The forward voltage (VF) ranges from 2.5V (min) to 3.6V (max), with a typical value of 3.1V at 1A. The reverse current (IR) is a maximum of 10 μA at a reverse voltage (VR) of 5V. The signal rise and fall times (Tr/Tf) are typically 30 nanoseconds (measured from 10% to 90%). The viewing angle (2θ1/2) is 150 degrees, where θ1/2 is the off-axis angle where the radiant intensity is half the value on the central axis.

3. Performance Curve Analysis

The datasheet includes several typical characteristic curves that are essential for circuit design and performance prediction under varying conditions.

3.1 Spectral Distribution

Figure 1 shows the relative radiant intensity as a function of wavelength. The curve is centered at 850 nm, confirming the peak emission wavelength, with the 50 nm half-width indicating the spectral spread of the emitted infrared light.

3.2 Forward Current vs. Ambient Temperature

Figure 2 illustrates the relationship between the allowable forward current and the ambient temperature. This derating curve is crucial for determining the maximum safe operating current at elevated temperatures to avoid exceeding the junction temperature limit.

3.3 Forward Current vs. Forward Voltage

Figure 3 presents the IV (Current-Voltage) characteristic curve. It shows the non-linear relationship, which is typical for diodes, and is used to calculate power dissipation (Vf * If) and to design appropriate current-limiting circuitry.

3.4 Relative Radiant Intensity vs. Ambient Temperature and Forward Current

Figures 4 and 5 depict how the optical output power (relative to its value at IF=1A) changes with ambient temperature and forward current, respectively. These graphs help designers understand efficiency variations and output stability under different operating conditions.

3.5 Radiation Pattern

Figure 6 is a polar radiation diagram showing the spatial distribution of the emitted infrared light. The wide, smooth lobe confirms the 150-degree viewing angle, which is important for applications requiring broad coverage or alignment tolerance.

4. Mechanical and Packaging Information

4.1 Outline Dimensions

The document provides a detailed mechanical drawing of the component. All dimensions are specified in millimeters, with a standard tolerance of ±0.1 mm unless otherwise noted. The drawing includes key features necessary for PCB footprint design and mechanical integration.

4.2 Suggested Soldering Pad Dimensions

A recommended PCB land pattern (soldering pad layout) is provided to ensure proper solder joint formation, mechanical stability, and thermal performance during the assembly process. Adhering to these dimensions is advised for reliable manufacturing.

4.3 Polarity Identification

The cathode is clearly marked in the package dimensions diagram. Correct polarity orientation during assembly is essential for the device to function.

5. Soldering and Assembly Guidelines

Proper handling and assembly are critical to maintaining device reliability and performance.

5.1 Storage Conditions

For sealed packages, storage should be at 30°C or less and 90% Relative Humidity (RH) or less, with a recommended use-within period of one year. For opened packages, the environment should not exceed 30°C or 60% RH. Components removed from their original packaging should be reflow-soldered within one week. For longer storage outside the original pack, storage in a sealed container with desiccant or in a nitrogen desiccator is recommended. Components stored out of packaging for more than a week should be baked at approximately 60°C for at least 20 hours before soldering.

5.2 Cleaning

If cleaning is necessary, only alcohol-based solvents like isopropyl alcohol should be used.

5.3 Soldering Parameters

Detailed soldering conditions are provided for both reflow and hand soldering processes. For reflow soldering: pre-heat at 150–200°C for a maximum of 120 seconds, with a peak temperature not exceeding 260°C for a maximum of 10 seconds (maximum of two reflow cycles allowed). For soldering iron use: a maximum temperature of 300°C for a maximum of 3 seconds per lead. The document references JEDEC standard profiles as a basis for process setup and emphasizes the need for board-specific characterization due to variations in design, pastes, and equipment.

6. Packaging and Ordering Information

6.1 Tape and Reel Package Dimensions

The component is supplied on 7-inch reels, with 600 pieces per reel. The packaging conforms to ANSI/EIA 481-1-A-1994 specifications. Detailed dimensions for the carrier tape and reel are provided. Notes specify that empty component pockets are sealed with cover tape and that a maximum of two consecutive missing parts are allowed.

7. Application Notes and Design Considerations

7.1 Intended Use and Cautions

The device is intended for ordinary electronic equipment in office, communication, and household applications. Consultation is required prior to use in applications where exceptional reliability is needed, especially where failure could jeopardize life or health (e.g., aviation, medical systems, safety devices).

7.2 Drive Circuit Design

As an LED is a current-operated device, a current-limiting resistor must be used in series with each LED when multiple devices are connected in parallel. This practice, illustrated as "Circuit Model (A)" in the datasheet, is essential to ensure intensity uniformity across all LEDs. The alternative circuit without individual resistors ("Circuit Model (B)") may result in brightness variations due to the natural forward voltage (Vf) distribution among the LEDs, causing current imbalance.

7.3 Thermal Management

Given the power dissipation rating of 3.6W and a thermal resistance (Rθj) of 9 K/W, effective thermal management on the PCB is necessary. Designers must ensure adequate copper area or heatsinking to keep the junction temperature within safe limits, especially when operating at high currents or in elevated ambient temperatures, as indicated by the derating curve.

8. Technical Comparison and Differentiation

This 850nm AlGaAs IRED is positioned for high-speed applications. Compared to standard 940nm GaAs IREDs often used in remote controls, the 850nm wavelength can offer better performance with silicon-based detectors (which have higher sensitivity around 800-900nm) and is commonly used in data transmission and surveillance systems. The high power output (320 mW/sr typical) and fast switching speed (30 ns typical) are key differentiators for applications requiring strong signals or high data rates.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the difference between radiant intensity (mW/sr) and total radiant flux (mW)?

A: Radiant intensity measures optical power emitted per unit solid angle (steradian) along the central axis, indicating how concentrated the beam is. Total radiant flux is the integrated optical power emitted in all directions. The wide 150° viewing angle of this device means its total flux is significantly higher than its axial intensity would suggest for a narrow-angle emitter.

Q: Can I drive this LED with a constant voltage source?

A: It is not recommended. LEDs require current control. The forward voltage (Vf) has a range (2.5V to 3.6V). A constant voltage source set within this range could lead to excessive current variation between units, potentially overdriving some and causing inconsistent brightness or damage. Always use a series resistor or a constant current driver.

Q: How do I interpret the viewing angle of 150 degrees (2θ1/2)?

A: The viewing angle is the full angle where the intensity is at least half of the peak (on-axis) intensity. Therefore, θ1/2 is 75 degrees from the axis. Light is emitted with useful intensity across this very wide 150-degree cone.

10. Design and Usage Case Examples

Case 1: Proximity Sensor / Object Detection: The emitter can be paired with a separate phototransistor or photodiode detector. The wide viewing angle simplifies alignment. An object passing between the emitter and detector interrupts the beam, triggering a detection signal. The high power allows for longer sensing distances or operation in environments with some ambient IR noise.

Case 2: Simple Infrared Data Link: The fast 30 ns rise/fall time enables it to be modulated at high frequencies (into the MHz range), suitable for short-range wireless data transmission. By driving it with a modulated current from a microcontroller or encoder IC, and using a tuned receiver circuit with a photodiode, a basic serial communication link can be established.

Case 3: Multi-Emitter Array for Illumination: For applications requiring area illumination in the infrared spectrum (e.g., for CCTV cameras with night vision), multiple units can be arranged on a PCB. The drive circuit must include individual current-limiting resistors for each emitter (as per Circuit A) to ensure uniform output across the array despite Vf variations.

11. Operational Principle

This device is an Infrared Emitting Diode (IRED). It operates on the principle of electroluminescence in a semiconductor p-n junction. When a forward current is applied, electrons and holes recombine in the active region (made of AlGaAs), releasing energy in the form of photons. The specific material composition (AlGaAs) and structure are engineered so that the energy bandgap corresponds to a photon wavelength of 850 nanometers, which is in the near-infrared region of the electromagnetic spectrum, invisible to the human eye but detectable by silicon-based sensors.

12. Industry Trends and Context

Infrared components continue to evolve towards higher efficiency, higher speed, and greater integration. Trends include the development of VCSELs (Vertical-Cavity Surface-Emitting Lasers) for more precise, high-speed data communication (e.g., in LiDAR and optical data links) and the integration of emitters with drivers and detectors with amplifiers into single modules. However, discrete components like this IRED remain vital for their cost-effectiveness, design flexibility, and reliability in a vast array of established and emerging applications, from consumer electronics to industrial automation and IoT sensors. The focus on RoHS and Green Product compliance reflects the industry-wide shift towards environmentally conscious manufacturing.