LTE-R38386AS-S Infrared Emitter and Receiver Datasheet - 850nm Wavelength - 3.6W Power - 3.1V Forward Voltage - Technical Documentation

1. Product Overview

This document elaborates on the specifications of a discrete infrared (IR) device, designed for applications requiring reliable light sources and sensing capabilities. The device integrates an IR emitter and detector with a peak wavelength of 850 nm, specifically engineered for high-performance applications demanding high output and stable operation.

The core advantage of this device lies in integrating a high-power infrared emitter with a compatible detector within a single package. This integration simplifies the design for reflective or proximity sensing applications. The emitter features high radiant intensity and a wide viewing angle, while the detector provides the necessary sensitivity for signal reception. This product complies with environmental regulations and is classified as RoHS and a green product.

Target markets include remote control systems, short-range wireless data transmission, security alarm systems, and various industrial or consumer electronic sensing applications that prefer the use of infrared technology.

2. In-depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

These ratings define the stress limits that may cause permanent damage to the device. Operation at or beyond these limits is not guaranteed. To ensure long-term reliability, such operation should be avoided.

• Power Dissipation (Pd):3.6 Watts. This is the maximum amount of heat the device can dissipate when the ambient temperature (Ta) is 25°C. Exceeding this value will cause excessive junction temperature rise.
• Peak Forward Current (I_FP):5 Amperes. This is the maximum current allowed under pulse conditions (300 pulses per second, 10μs pulse width). It is significantly higher than the DC rating, utilizing the device's transient thermal capacity.
• Direct forward current (I_F):1 Ampere. The maximum continuous forward current that the emitter can withstand.
• Reverse voltage (V_R):5 Volts. Applying a reverse voltage higher than this value may cause semiconductor junction breakdown.
• Thermal resistance (R_θJ):9 K/W. This parameter indicates the efficiency of heat conduction from the semiconductor junction to the environment. A lower value indicates better heat dissipation performance.
• Operating temperature range:-40°C to +85°C. The device is specified to operate normally within this ambient temperature range.
• Storage temperature range:-55°C to +100°C.
• Infrared soldering conditions:The package can withstand a peak reflow temperature of up to 260°C for a maximum duration of 10 seconds.

2.2 Electrical and Optical Characteristics

These parameters are measured under standard test conditions (Ta=25°C) and represent the typical performance of the device.

• Radiant intensity (I_E):630 mW/sr (typical), at I_F=1A. This parameter measures the optical power emitted per unit solid angle along the central axis, indicating the brightness of the light source.
• Total radiant flux (Φ_e):1340 mW (typical), at I_F=1A condition. This is the total optical power emitted in all directions.
• Peak emission wavelength (λ_P):850 nm (typical). The wavelength at which the optical output power reaches its maximum.
• Spectral line half-width (Δλ):50 nm (typical). The width of the emission spectrum at half maximum intensity, indicating spectral purity.
• Forward voltage (V_F):3.1 V (typical), at I_F=1A condition, range from 2.5V to 3.6V. The voltage drop across the device when passing the specified current.
• Reverse current (I_R):10 μA (max), at V_R=5V condition. Small leakage current when the device is reverse biased.
• Rise/fall time (t_r/t_f):30 ns (typical value). The time required for the light output to rise from 10% to 90% (or fall from 90% to 10%) of its maximum value. This determines the maximum modulation speed.
• Viewing angle (2θ_1/2):90 degrees (typical value). The full angle at which the radiation intensity is half of its on-axis (0°) value. A wide viewing angle is beneficial for broad coverage applications.

3. Performance Curve Analysis

The datasheet provides several key characteristic curves, which are crucial for understanding the device's behavior under different conditions.

3.1 Spectral Distribution

The spectral distribution curve shows the relationship between relative radiant intensity and wavelength. For this device, the peak center is at 850nm, with a typical half-width of 50nm. This characteristic is very important for matching the spectral sensitivity of the paired detector or ensuring compatibility with optical filters in the system.

3.2 Relationship Between Forward Current and Ambient Temperature

This derating curve illustrates how the maximum allowable DC forward current decreases as the ambient temperature increases. To prevent exceeding the maximum junction temperature, the drive current must be reduced when operating in high-temperature environments. The curve typically shows a linear decrease from the rated current at 25°C to zero current at the maximum junction temperature.

3.3 Relationship Between Forward Current and Forward Voltage

The I-V curve shows the exponential relationship between forward current and forward voltage. The typical V_FThe value is 3.1V, which is a key parameter for designing the drive circuit and calculating power consumption (P_d= V_F* I_F).

3.4 Relationship Between Relative Radiant Intensity, Forward Current, and Temperature

These curves show how the optical output power varies with drive current and ambient temperature. The output typically increases linearly with current up to a certain point, but at extremely high currents, efficiency may decline due to heating. The output also decreases with rising temperature, which is caused by a drop in internal quantum efficiency.

3.5 Radiation Pattern

Polar radiation diagram intuitively represents the viewing angle. This diagram confirms a half-angle of 90 degrees, showing the relative intensity at different off-axis angles. This is crucial for designing optical systems and aligning emitters and detectors within the system.

4. Mechanical and Packaging Information

4.1 Outline Dimensions

This device is housed in a surface-mount package. The outline drawing specifies all critical physical dimensions, including length, width, height, lead pitch, and the position of the optical window. Unless otherwise noted, tolerances are typically ±0.1mm. This drawing must be referenced when designing the PCB land pattern.

4.2 Recommended Land Pattern

Provides recommended PCB pad layout (footprint). This includes pad dimensions, shape, and spacing to ensure reliable solder joint formation during reflow soldering and provide sufficient mechanical strength. Following these recommendations helps prevent tombstoning and poor soldering.

4.3 Polarity Indication

The cathode is clearly marked in the footprint drawing. Correct polarity must be observed during assembly to prevent device damage. The provided tape and reel packaging also maintains consistent orientation for automatic placement.

5. Welding and Assembly Guide

5.1 Storage Conditions

Wannan na'urar tana da hankali ga danshi. Marufaffiyar marufi ya kamata a adana shi a cikin yanayi ≤30°C da ≤90% danshi na dangi, ana ba da shawarar amfani da shi cikin shekara guda. Da zarar buhun kariya ya buɗe, ya kamata a adana kayan a cikin yanayi ≤30°C da ≤60% danshi na dangi. Idan an fallasa shi cikin iskar muhalli fiye da mako guda, yana buƙatar gasa a kusan 60°C na aƙalla sa'o'i 20 kafin walda, don kawar da ruwan da aka sha, don hana faruwar "gwangwani" yayin walda mai jujjuyawa.

5.2 Reflow Soldering Temperature Profile

Ana ba da shawarar yin amfani da zane-zanen zafin jiki na walda mai jujjuyawa wanda ya dace da ma'aunin JEDEC. Mahimman sigogi sun haɗa da:

• Preheating:150–200°C, maximum 120 seconds, to gradually heat the circuit board and activate the flux.
• Peak temperature:Maximum 260°C. Time above 260°C should be minimized.
• Peak Time:Maximum 10 seconds. The device can withstand this temperature profile a maximum of two times.

The specific temperature profile must be characterized according to the actual PCB design, solder paste, and reflow oven used.

5.3 Manual soldering

If manual soldering is necessary, the soldering iron tip temperature should not exceed 300°C, and the contact time per solder joint should be limited to within 3 seconds. This operation should be performed only once.

5.4 Cleaning

If post-soldering cleaning is required, only alcohol-based solvents such as isopropanol may be used. The use of harsh or corrosive chemical cleaners should be avoided.

6. Packaging and Ordering Information

6.1 Tape and Reel Specifications

Components are supplied in embossed carrier tape, wound on 7-inch reels. Each reel contains 600 components. The packaging complies with the ANSI/EIA 481-1-A-1994 standard. The carrier tape has a cover tape to protect the components, and the specification allows for a maximum of two consecutive missing components in a reel.

6.2 Part Number

The base part number is LTE-R38386AS-S. This number should be used for ordering and identification.

7. Application Suggestions and Design Considerations

7.1 Typical Application Circuit

This device is suitable for general electronic equipment. For driving transmitters, it is a current-driven device.Strongly recommend using circuit model (A):When multiple devices are connected in parallel, a current-limiting resistor should be connected in series with each LED. This ensures uniform brightness by compensating for the natural differences in forward voltage (V_F) between individual LEDs.Not recommended to use circuit model (B):That is, LEDs are directly connected in parallel without their respective resistors, as this may lead to significant brightness mismatch, and the LED with the lowest forward voltage (V_F.

) may draw excessive current.

• 7.2 Design ConsiderationsThermal Management:
• Due to the power dissipation of up to 3.6W, proper thermal design on the PCB is critical. Use sufficient copper foil area (thermal pads) connected to the device pins to conduct heat away from the junction.Drive Current Selection:
• Select the operating current based on the required radiant intensity and the thermal derating at the application's maximum ambient temperature. Do not exceed the absolute maximum DC current of 1A.Optical Alignment:
• For reflective sensing applications using both an emitter and a detector, careful mechanical design is required to align the detector's field of view with the emitter's illumination area.Electrical Noise:

For the detector side, the potential impact of ambient light noise must be considered. The datasheet mentions that a filter can be provided for the photodiode/transistor, but it does not explicitly state whether this specific detector includes a filter.

7.3 Application Restrictions

This device is not designed for applications where failure could endanger life or health, such as in aviation, traffic control, medical, or critical safety systems. For such applications, consult the manufacturer before design adoption.

8. Technical Comparison and Differentiation

• Although this datasheet does not provide a direct comparison with other part numbers, the key differentiating features of this device can be inferred:Integrated Solution:
• The integration of emitter and detector reduces component count and simplifies optical alignment compared to procuring discrete components.High Power:
• A radiant intensity of 630 mW/sr and a power dissipation rating of 3.6W indicate a high-output device suitable for applications requiring longer range or stronger signals.High Speed:
• A rise/fall time of 30 ns supports high-frequency modulation, making it suitable for fast data transmission or pulsed operation.Wide Viewing Angle:

90-degree half-angle provides a wide coverage range, suitable for applications such as proximity sensing or where alignment requirements are not stringent.

9. Frequently Asked Questions (Based on Technical Parameters)
Q: Can I drive this LED continuously at 1A?

A: Yes, but only if the ambient temperature is 25°C or lower, and you have implemented sufficient heat dissipation measures to keep the junction temperature within limits. At higher ambient temperatures, the current must be derated according to the provided curve.
Q: What is the difference between radiant intensity and total radiant flux?

A: Radiant intensity (mW/sr) measures the power per unit solid angle in a specific direction (usually axial). Total radiant flux (mW) measures the sum of the optical power emitted in all directions. The former is relevant for focusing applications, the latter for total light output.
Q: Why does each LED in parallel need a series resistor?_FA: The forward voltage (V_F) of an LED has a negative temperature coefficient and manufacturing variations. Without individual resistors, an LED with a slightly lower forward voltage (V

) will draw a disproportionately higher current, leading to uneven brightness and potential thermal runaway in that device.
Q: How to understand the soldering condition of "260°C for 10 seconds"?

A: This means the device package can withstand the high temperature of lead-free reflow soldering. Your reflow oven temperature profile should be designed so that the device body temperature does not exceed 260°C, and the time within a few degrees of this peak is less than 10 seconds.

10. Practical Application Examples
Design Case: Automatic Faucet Proximity Sensor

In this application, the emitter and detector are mounted side-by-side behind a waterproof window. The emitter continuously emits an 850nm infrared beam. When a hand is placed under the faucet, the infrared light reflects off the hand back to the detector. The microcontroller monitoring the detector's output detects a significant increase in the signal, thereby triggering the water valve to open.
1. Design Steps:Drive Circuit:
2. Use circuit model (A). Set the transmitter current to, for example, 500mA using a constant current source or a voltage source with a series resistor to provide a strong signal well below the limit.Detector Interface:
3. The photodetector (which may be a phototransistor in this package) will be connected in a common-emitter configuration with a pull-up resistor. When infrared light is detected, the collector voltage will drop.PCB Layout:
4. Follow the recommended pad layout. Include large copper areas connected to the device ground pins for heat dissipation. Keep analog sensing traces away from noisy digital lines.Optical/Mechanical:
5. Design the housing so that the transmitter's 90-degree conical beam overlaps with the detector's field of view in the desired sensing area (e.g., 5-15 cm from the faucet head).Software:

Implement filtering in the microcontroller to distinguish the reflected signal from ambient infrared noise (e.g., from sunlight or heaters).

11. Working Principles
The device comprises two primary components:Infrared Emitter (IRED):

This is typically a gallium arsenide (GaAs) or aluminum gallium arsenide (AlGaAs) semiconductor diode. When forward-biased, electrons and holes recombine in the active region, releasing energy in the form of photons. The material composition (AlGaAs) is engineered to produce photons with a wavelength of approximately 850nm, which falls within the near-infrared spectrum and is invisible to the human eye.Infrared Detector:

This is a photodiode or phototransistor made of silicon or other semiconductor materials sensitive to infrared light. When photons with sufficient energy strike the active area of the detector, they generate electron-hole pairs. In a photodiode, when reverse-biased, this produces a photocurrent proportional to the light intensity. In a phototransistor, the photocurrent acts as a base current, causing a larger collector current to flow, thereby providing internal gain.

12. Teknoloji Trendleri
Infrared devices continue to develop in several directions related to this product category:Efficiency improvement:
Ongoing materials science research aims to improve the wall-plug efficiency (optical power output/electrical power input) of IREDs, reducing heat generation and power consumption at the same light output.Kasi ya juu:
Mahitaji ya vifaa vya matumizi ya kaya (mfano, Itifaki ya Shirika la Data ya Infrared) kwa uhamisho wa data wa kasi zaidi yamesababisha maendeleo ya vifaa vilivyo na muda mfupi wa kupanda/kushuka, na hivyo kuwezesha mawasiliano yenye upana wa bandi ya juu.Kupunguzwa kwa ukubwa:
Mwelekeo wa kupunguza ukubwa wa vifaa vya elektroniki unasababisha kupunguzwa kwa ukubwa wa kifurushi cha vifaa, huku ukidumisha au kuboresha utendaji.Integration: