Infrared LED Device Datasheet - Peak Wavelength 940nm - Chinese Technical Documentation

1. Product Overview

Bu belge, bir kızılötesi (IR) ışık yayan diyot (LED) cihazının teknik özelliklerini sağlar. Bu cihaz, öncelikle uzaktan kumandalar, yakınlık sensörleri ve gece görüş aydınlatması gibi görünmez ışık kaynağı gerektiren sistemler için tasarlanmıştır. Cihazın temel avantajı, silikon tabanlı fotodedektörlerle uyumluluğu için optimize edilmiş ve insan gözü tarafından son derece düşük görünürlüğe sahip olan spesifik tepe dalga boyudur. Hedef pazarlar arasında tüketici elektroniği, endüstriyel otomasyon, güvenlik sistemleri ve güvenilir kızılötesi sinyal iletimi veya algılama gerektiren otomotiv uygulamaları bulunur.

2. In-depth Technical Parameter Analysis

The provided data specifies a key photometric parameter of this infrared LED.

2.1 Photometric characteristics

The most critical parameter defined is the peak wavelength (λp).

• Peak wavelength (λp):940 nanomita (nm). O lenei tau e faʻailoa mai ai le tulaga faʻapitoa e faʻaolaina ai e le LED le malosi sili o le malamalama i le fusi o galu electromagnetic. O le umi o le galu 940nm o loʻo i totonu atoa o le vaʻaiga lata ane o le infrared (NIR). O lenei umi galu e sili ona aoga ona e fetaui lelei ma le maualuga o le maaleale o le silicon photodiode masani ma phototransistors, e mautinoa ai le lelei o le auina atu ma le mauaina o faailo. E le gata i lea, pe a faʻatusatusa i umi galu infrared pupuu e pei o le 850nm, o le malamalama 940nm e sili atu ona le iloa e pei o se mumu vaivai, ma faʻafaigofie ai ona talafeagai mo faʻaoga natia.

O isi faʻamatalaga masani o le malamalama o le LED infrared, e pei o le malosi faʻavevela (iunite: milliwatts i le steradian, mW/sr), tulimanu vaʻaia (iunite: tikeri), ma le voli saʻo i lalo o se taimi patino, e le o faʻaalia manino i le vaega na tusia, ae e taua tele mo le mamanu atoa o le matagaluega.

2.2 Electrical parameters

Although specific numerical values are not listed in the provided text, the electrical behavior of an infrared LED is defined by several key parameters that the designer must consider.

• Forward Voltage (Vf):The voltage drop across the LED when it is conducting current. For a typical GaAs-based infrared LED, this value typically ranges from 1.2V to 1.6V at its nominal forward current.
• Forward Current (If):The recommended continuous operating current. Exceeding the maximum rated forward current may lead to rapid performance degradation or catastrophic failure.
• Reverse Voltage (Vr):Maximum voltage an LED can withstand when biased in the non-conducting direction. Infrared LEDs typically have very low reverse voltage ratings (often around 5V) and are susceptible to damage from reverse voltage spikes.
• Power Dissipation:Total electrical power converted into heat and light (Vf * If). Proper thermal management is required to prevent overheating.

2.3 Thermal Characteristics

Thermal management is crucial for the lifespan and stable performance of LEDs.

• Junction Temperature (Tj):Temperature of the semiconductor chip active region. Maximum allowable junction temperature is a critical limitation.
• Thermal resistance (Rθj-a):This parameter, measured in degrees Celsius per watt (°C/W), indicates the efficiency of heat transfer from the LED junction to the ambient air. A lower value signifies better heat dissipation capability. Package design significantly influences this value.
• Derating curve:A graph showing how the maximum allowable forward current decreases as ambient or junction temperature increases. Operating within these limits is critical for reliability.

3. Explanation of the Grading System

High-volume LED manufacturing leads to variations in key parameters. Binning is the process of sorting components into different groups (bins) based on measured performance to ensure consistency for end users.

3.1 Wavelength Grading

For this 940nm infrared LED, components will be tested and binned according to their actual peak wavelength. For example, bins may be defined as 935-940nm, 940-945nm, etc. This allows designers to select LEDs with tighter wavelength tolerances if the application requires precise spectral matching.

3.2 Radiant Intensity/Optical Power Binning

LEDs are also binned according to their radiant output. This is crucial for applications requiring uniform brightness or specific signal strength. Bins are defined by minimum and maximum radiant intensity values at a standardized test current (e.g., 20-25 mW/sr, 25-30 mW/sr).

3.3 Forward Voltage Binning

To simplify current-limiting circuit design and ensure consistent behavior in parallel arrays, LEDs are binned by forward voltage (Vf). Common bins may group LEDs with Vf in ranges such as 1.2V-1.3V, 1.3V-1.4V, etc.

4. Performance Curve Analysis

Graphical data is crucial for understanding the behavior of devices under various operating conditions.

4.1 Current-Voltage (I-V) Characteristic Curve

This curve plots the relationship between forward current (If) and forward voltage (Vf). It shows the typical exponential relationship of a diode. The curve is used to determine the operating point and to design appropriate current-limiting resistors or drive circuits. The "knee" voltage, where the current begins to increase rapidly, is a key characteristic.

4.2 Temperature Dependence

Several curves illustrate the temperature effect.

• Forward Voltage vs. Temperature:Typically shows that Vf decreases linearly with increasing junction temperature (approximately -2mV/°C for infrared LEDs). This is important for constant current drivers.
• Radiant Intensity vs. Temperature:Show how the light output decreases as the temperature increases. This derating is crucial for applications operating in high-temperature environments.
• Relative Spectral Distribution vs. Temperature:Shows how the peak wavelength shifts slightly (typically towards longer wavelengths) as the temperature increases.

4.3 Spectral Distribution

The chart plots relative radiant power versus wavelength. It shows the peak at 940nm and the spectral bandwidth (typically full width at half maximum, or FWHM, which is usually around 40-50nm for infrared LEDs). A narrower bandwidth indicates light that is closer to being monochromatic.

5. Mechanical and Packaging Information

The provided excerpt contains specific packaging details.

5.1 Packaging Level

This component is protected by a multi-layer packaging system:

• Electrostatic Discharge (ESD) Protective Bag:The primary container for storing individual LED components or reels. This bag is made of static dissipative material to prevent damage from electrostatic discharge during handling and storage.
• Inner Box:A smaller box or tray used to hold multiple ESD bags or reels, providing physical structure and additional protection.
• Outer Box:The primary container used for shipping, containing multiple inner boxes. Designed to remain sturdy during transportation and storage.

5.2 Packaging Quantity

The document explicitly lists "Packaging Quantity" as a key parameter. This refers to the number of individual LED components contained in a standard shipping unit (e.g., quantity per reel, per tube, or per bag within an inner box). For surface-mount devices, common quantities are 1000, 2000, or 5000 pieces per reel.

5.3 Physical Dimensions and Polarity

While precise dimensions are not provided, typical infrared LED packages (such as 3mm or 5mm through-hole LEDs, or surface-mount packages like 0805, 1206) have detailed mechanical drawings. These drawings specify the body length, width, height, lead pitch, and lead dimensions. Crucially, they include polarity identification, typically indicating the cathode (negative terminal) via a flat side on the lens, a shorter lead, a dot on the package, or a specific marking on the solder pad.

6. Soldering and Assembly Guide

Correct assembly is crucial for reliability.

6.1 Reflow Soldering Temperature Profile

For surface-mount infrared LEDs, the recommended reflow soldering temperature profile must be followed. This includes:

• Preheat/Ramp-up Rate:Typically 1-3°C per second to avoid thermal shock.
• Soak Zone:Maintain at a temperature below the solder liquidus for a period to activate the flux and equalize the board temperature.
• Reflow (Liquidus) Zone:Peak temperature must be high enough to melt the solder (e.g., 240-250°C for SAC305), yet low enough and short enough in duration to avoid damaging the LED (maximum package body temperature is typically 260°C for 10 seconds).
• Cooling rate:Controlled cooling process to properly solidify solder joints.

6.2 Key Considerations

• ESD Protection:Always handle components in an ESD-safe environment using a grounded wrist strap and conductive mat.
• Moisture Sensitivity Level (MSL):If applicable, the packaging will have an MSL rating (e.g., MSL 3). Components exceeding their floor life must be baked before reflow to prevent "popcorn" effect damage.
• Cleaning:Use only compatible cleaning solvents to avoid damaging the LED lens or epoxy.
• Mechanical Stress:Avoid applying direct pressure to the LED lens during placement or testing.

6.3 Storage Conditions

Components should be stored in their original unopened ESD bags in a controlled environment. Recommended conditions are typically a temperature between 5°C and 30°C, with relative humidity below 60%. Avoid exposure to direct sunlight, corrosive gases, or excessive dust.

7. Packaging and Ordering Information

The document's lifecycle data shows "Revision: 5" and "Valid until: Permanent," indicating it is a stable, non-obsolete controlled document released on May 27, 2013. Packaging specifications are clearly defined in Section 5.1. The ordering code or model number typically follows a naming convention that encodes key attributes such as package type, wavelength bin, intensity bin, and packaging quantity (e.g., "IR940-SMD1206-B2-2K" might represent a 1206 packaged 940nm infrared LED, intensity bin B2, supplied on a 2000-piece reel).

8. Application Recommendations

8.1 Typical Application Scenarios

• Infrared Remote Control:Used for televisions, audio systems, and set-top boxes. The 940nm wavelength is the industry standard.
• Proximity and Presence Sensors:Used in smartphones to disable the touchscreen during calls, automatic faucets, and security light switches.
• Object Counting and Detection:For vending machines, industrial assembly lines, and printing equipment.
• Night Vision Illumination:Paired with infrared-sensitive cameras for surveillance in low-light conditions.
• Optical data transmission:Used for short-range, low-speed serial communication (IrDA) or industrial data links.

8.2 Design Considerations

• Drive Circuit:Always use a series current-limiting resistor or a constant current driver. Never connect an LED directly to a voltage source.
• Heat Dissipation:For high current operation or high ambient temperature, ensure sufficient PCB copper area or external heat sink to manage the thermal resistance of the LED.
• Optical Design:Consider the viewing angle of the LED. Use lenses or reflectors to collimate or diffuse the beam as required by the application.
• Photodetector Matching:Ensure the selected photodetector (photodiode, phototransistor) has high sensitivity at 940nm. If ambient light interference is severe, use an infrared filter to block visible light.
• Electrical Noise Immunity:In sensor applications, modulate the infrared signal (e.g., using a 38kHz carrier) and use a tuned receiver to suppress ambient light interference from sunlight or fluorescent lamps.

9. Technical Comparison

Compared to other infrared light sources, this 940nm LED has specific advantages.

• Compared with 850nm infrared LED:940nm light has much lower visibility as a faint red glow, making it superior for covert surveillance. However, silicon photodetectors are slightly less sensitive at 940nm than at 850nm, and atmospheric absorption is also slightly higher.
• Compared with incandescent infrared lamps:LED yana da inganci sosai, lokacin amsawa ya fi sauri (yana goyan bayan babban saurin daidaitawa), ƙarfin injiniya ya fi girma, kuma yana da tsawon rayuwa mai tsawo (dubun sa'o'i).
• Idan aka kwatanta da Laser Diode:LED yana da mafi faɗin fitarwa na bakan haske da mafi girma yanki na fitarwa, yana samar da haske mai watsewa wanda ke da sauƙin amfani don hasken gabaɗaya da na'urar ji. Suna da arha sosai, kuma ba sa buƙatar rikitaccen kewayawa da kewayon aminci na Laser Diode.

10. Frequently Asked Questions (FAQ)

Q1: What is the purpose of the 940nm peak wavelength?
A1: The 940nm wavelength is optimal because it matches well with the sensitivity of silicon photodetectors while being nearly invisible to the human eye, making it ideal for covert sensing and remote control applications.

Q2: How to determine the correct current-limiting resistor value?
A2: Yi amfani da dokar Ohm: R = (ƙarfin wutar lantarki - Vf) / If. Dole ne ku san ƙarfin wutar lantarkin ku (Vsupply), ƙarfin lantarki na gaba (Vf) a cikin bayanan LED ko rarrabuwa, da kuma ƙarfin kwarara na gaba (If) da ake buƙata. Koyaushe ku tabbatar cewa ƙarfin ƙimar wutar lantarki na resistor (P = (Vsupply - Vf) * If) ya isa.

Q3: Zan iya amfani da wannan LED a waje?
A3: I, amma kula. Ruwan tabarau na epoxy na iya tsufa a ƙarƙashin hasken UV na dogon lokaci. Mafi mahimmanci, hasken rana mai haske yana ɗauke da ƙaƙƙarfan sassa na infrared, wanda zai iya cika mai karɓa. Yin amfani da tacewa na gani da siginar daidaitawa yana da mahimmanci don aiki mai dogaro a waje.

Q4: Why is ESD protection so important for LEDs?
A4: The semiconductor junctions in LEDs are extremely sensitive to high-voltage electrostatic discharge. An ESD event can immediately reduce light output, increase leakage current, or cause complete failure without any visible damage.

Q5: What does "Packaging Quantity" refer to?
A5: It specifies the number of individual LED elements provided in a standard sales unit, such as on a reel, in a tube, or within an anti-static bag. This is crucial for production planning and inventory management.

11. Practical Use Cases

11.1 Simple Proximity Sensor

A basic reflective sensor can be constructed by placing a 940nm infrared LED and a phototransistor side-by-side. The LED is driven by a pulsed current. When an object approaches, it reflects the infrared light back to the phototransistor, causing its collector current to increase. A comparator circuit can then trigger a digital output signal. This design is used for paper detection in printers and hand dryer activation.

11.2 Long-Range Infrared Illuminator for CCTV

For night vision security cameras, an array consisting of multiple high-power 940nm LEDs needs to be constructed. The LEDs are driven by constant-current drivers capable of supplying hundreds of milliamps. A Fresnel lens is placed in front of the array to collimate the light into a beam, extending the effective illumination range to tens of meters. For such a high-power design, thermal management via a large aluminum heat sink is crucial.

12. How It Works

An infrared light-emitting diode (IR LED) is a semiconductor p-n junction device. When forward biased (applying a positive voltage to the p-side relative to the n-side), electrons from the n-region are injected into the p-region, while holes from the p-region are injected into the n-region. These minority carriers recombine with majority carriers in the opposite regions. In direct bandgap semiconductors commonly used for IR LEDs, such as gallium arsenide (GaAs), this recombination event releases energy in the form of photons (light particles). The wavelength (color) of the emitted photon is determined by the bandgap energy (Eg) of the semiconductor material, according to the formula λ = hc/Eg, where h is Planck's constant and c is the speed of light. By adjusting the semiconductor alloy composition (e.g., using AlGaAs or InGaAs), the bandgap, and thus the emission wavelength, can be precisely controlled to produce the specified 940nm output here.

13. Technology Trends

Kızılötesi LED teknolojisi alanındaki gelişmeler devam etmektedir. Ana trendler şunları içerir:

• Güç ve Verimlilik Artışı:Ongoing advancements in materials science and packaging are yielding infrared LEDs with higher radiant flux and electro-optical conversion efficiency, enabling smaller devices or longer illumination distances at the same input power.
• Miniaturization:The demand for smaller consumer electronics is driving infrared LEDs into smaller surface-mount packages (e.g., 0402, 0201) and chip-scale packages (CSP).
• Integrated Solution:The trend is to integrate infrared LEDs, photodetectors, driver circuits, and signal processing (such as ambient light suppression) into a single module or System-in-Package (SiP), thereby simplifying end-user design.
• Expanding to New Wavelengths:Although 850nm and 940nm dominate, interest in other infrared wavelengths is growing for specialized applications, such as 1050nm for eye-safe LiDAR or specific bands for gas sensing.
• Improved Thermal Management:New package designs with lower thermal resistance and materials with better thermal conductivity are extending LED lifespan and supporting higher drive currents.