LTE-R38381L-S Infrared Emitter and Detector Datasheet - 940nm Wavelength - 1A Forward Current - 1.8W Power - Technical Documentation

1. Product Overview

This document provides the complete technical specifications for a discrete infrared emitter component. This device is specifically designed for applications requiring high-power, reliable infrared light sources. It utilizes a Gallium Arsenide (GaAs) chip that emits light at a peak wavelength of 940 nanometers, which falls within the near-infrared spectrum and is invisible to the human eye. The primary function of this component is to serve as a controlled infrared emission source in various electronic systems.

1.1 Core Advantages and Target Market

This component offers several key advantages for infrared applications. It features high radiant intensity, enabling strong signal transmission. Its design supports high drive current, which contributes to its enhanced output power. The device also boasts a long service life and high reliability in performance. It complies with environmental regulations such as RoHS, making it a green product. The target application areas for this infrared emitter are broad, primarily focusing on infrared emitters for remote control systems, as well as PCB-mounted infrared sensors for proximity detection, object sensing, or data transmission.

2. Technical Parameters: In-depth and Objective Interpretation

The following sections provide a detailed and objective analysis of the device's key technical parameters based on their specified limits.

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 and should be avoided in reliable designs.

• Power Dissipation (Pd):1.8 Watts. This is the maximum power the device can dissipate as heat at an ambient temperature (TA) of 25°C. Exceeding this value will cause excessive junction temperature rise.
• Peak Forward Current (IFP):5 Amperes. This is the maximum allowable current under pulsed conditions (300 pulses per second, 10 microsecond pulse width). It is significantly higher than the DC rating, utilizing the thermal inertia of the device.
• DC Forward Current (IF):1 Ampere. This is the maximum continuous forward current the device can withstand.
• Reverse Voltage (VR):5 volts. Applying a reverse voltage higher than this value may cause semiconductor junction breakdown.
• Thermal Resistance (RθJ):10 K/W. This parameter indicates the efficiency of heat conduction from the semiconductor junction to the environment. A lower value means better heat dissipation performance.
• Operating Temperature Range:-40°C to +85°C. The device is guaranteed to operate normally within this ambient temperature range.
• Storage Temperature Range:-55°C to +100°C.

2.2 Electrical and Optical Characteristics

Hizi ni vigezo vya utendaji vya kawaida na vinavyohakikishwa vilivyopimwa chini ya masharti maalum ya majaribio (isipokuwa imeelezwa, TA=25°C).

• Mwangaza wa mnururisho (I_E):160 mW/sr (kiwango cha chini). Kigezo hiki hupima nguvu ya mwanga inayotolewa kwa kila steradian kwenye mhimili. Inafafanua nguvu ya boriti ya mwanga katika mwelekeo maalum.
• Jumla ya mtiririko wa mnururisho (Φ_e):590 mW (kiwango cha kawaida). Hii ndiyo jumla ya nguvu ya mwanga inayotolewa na kifaa kwa mwelekeo wote (steradian 4π).
• Urefu wa wimbi wa kilele cha mnururisho (λ_P):940 nm (kiwango cha kawaida). Urefu wa wimbi ambao nguvu ya mwanga inayotolewa inafikia thamani yake ya juu zaidi.
• Upana wa nusu ya mstari wa wigo (Δλ):50 nm (thamani ya kawaida). Hii ni upana wa wigo wakati nguvu ya mionzi ni angalau nusu ya thamani yake ya kilele. Inaeleza usafi wa rangi (urefu wa wimbi) wa mwanga unaotolewa.
• Voltage ya mbele (V_F):1.8V (thamani ya kawaida), 2.3V (thamani ya juu), chini ya I_F=1A. Kupungua kwa voltage kwenye kifaa wakati kinapita mkondo maalum wa mbele.
• Mkondo wa nyuma (I_R):10 μA (thamani ya juu), chini ya V_R=5V. Mkondo mdogo wa uvujaji unaopita wakati kifaa kimewekwa kinyume.
• Muda wa kupanda/kushuka (t_r/t_f):30 ns (thamani ya kawaida). Muda unaohitajika kwa mwitikio wa pato la macho kwa mkondo wa hatua kupanda kutoka 10% hadi 90% (au kushuka kutoka 90% hadi 10%) ya thamani yake ya mwisho. Hii huamua kasi ya juu ya udhibiti.
• Pembe ya mtazamo (2θ_1/2):90 degrees (typical). Full angle at which the radiation intensity is half of the center (0°) value. A 90° angle indicates a wide beam pattern.

3. Performance Curve Analysis

The datasheet contains multiple graphs illustrating the device's behavior under various conditions. These curves are crucial for understanding nonlinearities and temperature dependencies.

3.1 Spectral Distribution

The graph (Figure 1) shows the relationship between relative radiant intensity and wavelength. The curve is centered at 940 nm with a typical half-width of 50 nm. This confirms that the device emits in the near-infrared region, which is optimal for many sensors and remote controls that filter out visible light.

3.2 Forward Current vs. Forward Voltage (I-V Curve)

The I-V curve (Figure 3) demonstrates the typical exponential relationship of a diode. At the rated current of 1A, the typical forward voltage is 1.8V. Designers must ensure the drive circuit can provide this voltage at the required current.

3.3 Temperature Dependence

Key graphs illustrate the temperature effects:

• Forward Current vs. Ambient Temperature (Figure 2):It shows how the maximum allowable forward current decreases with increasing ambient temperature due to a fixed power dissipation limit.
• Relative Radiant Intensity vs. Ambient Temperature (Figure 4):It indicates that the optical output power decreases with increasing junction temperature. This is a key factor for maintaining consistent performance.
• Relative Radiant Intensity vs. Forward Current (Figure 5):It shows a sublinear relationship between drive current and light output, especially at higher currents where efficiency may decrease and heat generation increases.

3.4 Radiation Pattern

The radiation pattern (Figure 6) is a polar plot showing the angular distribution of emitted light. The 90° viewing angle is visually confirmed, showing intensity drops to half at ±45° from the central axis. This pattern is important for aligning the emitter with the detector or ensuring sufficient coverage in sensing applications.

4. Mechanical and Packaging Information

4.1 Outline Dimensions

The device uses a standard through-hole package form. The outline drawing specifies body dimensions, lead pitch, and lead diameter. Unless otherwise specified, all dimensions are in millimeters, with a typical tolerance of ±0.1 mm. The cathode is marked on the package, which is crucial for correct orientation during PCB assembly.

4.2 Recommended Pad Dimensions

Chati hutoa vipimo vinavyopendekezwa vya mchoro wa pedi (kifurushi) kwa muundo wa PCB. Kufuata mapendekezo haya husaidia kuhakikisha mwunganiko wa kuaminika wa mchomeaji na utulivu unaofaa wa kiufundi baada ya uchomeaji wa wimbi au uchomeaji wa reflow.

5. Soldering and Assembly Guide

5.1 Soldering Conditions

Spec inatoa mwongozo wazi kwa njia mbili za uchomeaji:

• Reflow soldering:Recommended for surface mount assembly. The temperature profile must include a preheat phase (150-200°C), with a peak temperature not exceeding 260°C, and the time above 260°C should be no longer than 10 seconds. The device can withstand this temperature profile a maximum of two times.
• Hand soldering (soldering iron):The soldering iron tip temperature should not exceed 300°C, and the contact time per lead should be limited to within 3 seconds. This operation should be performed only once.

Provides a reflow temperature profile compliant with JEDEC standards as a general target reference, emphasizing the need to adhere to both JEDEC limits and the solder paste manufacturer's specifications.

5.2 Storage and Handling

• Storage (sealed bag):Devices should be stored in an environment of ≤30°C and relative humidity (RH) ≤90%. In a moisture barrier bag with desiccant, the shelf life is one year.
• Storage (Opened Bag):After opening, the ambient conditions should not exceed 30°C / 60% RH. Components should be used within one week. For long-term storage outside the original packaging bag, they must be stored in a sealed container with desiccant or in a nitrogen dry cabinet.
• Baking:If devices are exposed to ambient air for more than one week, baking prior to soldering is recommended, at 60°C for at least 20 hours, to remove absorbed moisture and prevent "popcorn" effect during reflow.

5.3 Cleaning

If cleaning is required after soldering, only alcohol-based solvents such as isopropyl alcohol should be used to avoid damage to the package or lens material.

5.4 Njia ya Kuendesha

A key design note emphasizes that LEDs are current-driven devices. To ensure uniform brightness when driving multiple LEDs in parallel, an independent current-limiting resistor must be connected in series with each LED. This compensates for minor differences in the forward voltage (V_F) of individual devices, preventing current imbalance and inconsistencies in illumination or output power.

6. Ufungaji na Taarifa za Kuagiza

6.1 Vipimo vya Ufungaji wa Tape na Reel

Detailed mechanical drawings specify the dimensions of the carrier tape, the cavities that house the components, and the overall reel (mentioning a diameter of 7 inches). The carrier tape is sealed with a cover tape to protect the components during transportation and automated assembly.

6.2 Vipimo vya Ufungaji

Key packaging details include:

• Reel size: 7 inches.
• Quantity: 600 pieces per reel.
• Quality: The maximum number of consecutive missing components in the carrier tape is two.
• Standard: Packaging conforms to ANSI/EIA 481-1-A-1994 specification.

7. Application Recommendations and Design Considerations

7.1 Typical Application Scenarios

Based on its specifications, this infrared emitter is ideally suited for:

• Kiremoteka ya Infrared:Inatumika kwenye televisheni, mifumo ya sauti na vifaa vingine vya matumizi ya kaya. Urefu wa wimbi wa 940nm ni kiwango cha wengi wa vipokeaji vya infrared.
• Ufahamu wa Ukaribu na Kitu:Inaunganishwa na photodiode au phototransistor kugundua uwepo, ukosefu au umbali wa kitu kwa kutafakari mwanga wake wa infrared.
• Swichi ya Kiotiki na Encoder:Kuzuia mwanga kati ya transmitter na detector ili kuunda swichi isiyogusa au kupima mzunguko/nafasi.
• Uhamisho wa Data wa Umbali Mfupi:Inatumika kwa matumizi kama ya IrDA au muunganisho rahisi wa data isiyo na waya, ikitumia wakati wake wa haraka wa kupanda/kushuka kwa modulation.

7.2 Design Considerations

• Thermal Management:With a power dissipation of 1.8W and a thermal resistance of 10 K/W, driving the device at maximum DC current generates significant heat. For continuous operation, especially at high ambient temperatures, sufficient PCB copper area (thermal pad) or a heatsink may be required.
• Current Drive Circuit:Use a constant current driver or a voltage source with a series resistor to set the current. Avoid driving directly from a logic pin or an unregulated voltage source.
• Optical Design:Consider the 90° viewing angle. For long-distance or directional beams, a lens may be needed to collimate the light. For wide-area illumination, the native angle may be sufficient.
• Pairing with Detector:Hakikisha kigunduzi cha mwanga (diodi ya mwanga ya PIN, transistor ya mwanga) kilichochaguliwa kina usikivu kwa eneo la 940nm. Kutumia kigunduzi chenye kichujio cha kuzuia mwanga wa mchana kitaboresha uwiano wa ishara-kwa-kelele chini ya hali ya mwanga wa mazingira.

8. Technical Comparison and Differentiation

Ingawa ulinganishaji wa moja kwa moja unahitaji data maalum ya washindani, kulingana na maelezo yake mwenyewe, sifa muhimu za kujitofautisha za kifaa hiki ni pamoja na:

• Uwezo wa Nguvu ya Juu:Uwezo wa mkondo wa moja kwa moja wa 1A na ukadiriaji wa mkondo wa msukumo wa 5A unaonyesha muundo wake wa chip na ufungaji ni imara, unaoweza kufikisha pato la juu.
• Pembe ya Mtazamo Pana:Pembe ya 90° hutoa eneo la usambazaji pana, linalofaa kwa matumizi ya kugundua ambayo yanahitaji usawa usio mkali au yanahitaji mwanga wa eneo.
• Kasi ya Kubadili Haraka:Muda wa kawaida wa kupanda/kushuka wa 30ns unaruhusu usindikaji wa masafa ya juu, ukifanya viwango vya haraka vya uhamishaji data katika matumizi ya mawasiliano ikilinganishwa na vifaa vilivyo polepole zaidi.
• Uthabiti Uliokomaa:Kumbukumbu ya viwango vya JEDEC pamoja na mwongozo wa kina wa kuunganisha/usikivu wa unyevu, zinaonyesha kifaa hiki kimeundwa kwa mchakato thabiti wa utengenezaji.

9. Maswali Yanayoulizwa Mara kwa Mara (Kulingana na Vigezo vya Kiufundi)

9.1 Je, naweza kutumia pini ya microcontroller ya 5V kuendesha LED hii moja kwa moja?

Hapana, hii haipendekezi, na inaweza kuharibu LED au microcontroller.LED hii ina kushuka kwa kawaida kwa voltage ya 1.8V kwa mkondo wa 1A. Pini ya microcontroller haiwezi kutoa mkondo wa 1A, na kuunganishwa moja kwa moja kwenye 5V bila kizuizi cha mkondo kungejaribu kuchota mkondo mwingi unaoharibu. Lazima utumie saketi ya kuendesha (transistor/MOSFET) iliyo na upinzani wa mfululizo ili kudhibiti mkondo kwa thamani inayotakiwa.

9.2 Kwa nini pato linapungua kwenye joto la juu?

Ufanisi wa nyenzo za semiconductor kubadilisha mkondo kuwa mwanga (Internal Quantum Efficiency) hupungua kadiri joto la kiungo linavyopanda. Hii ni sifa ya msingi ya fizikia. Chati katika Mchoro 4 inaweka kipimo kwa upungufu huu, ambayo lazima izingatiwe katika miundo inayofanya kazi katika anuwai pana ya halijoto ili kuhakikisha utendakazi thabiti wa macho.

9.3 Nini tofauti kati ya nguvu ya mionzi na jumla ya mtiririko wa mionzi?

Radiant Intensity (mW/sr)ni kipimo chamwelekeonguvu inayotolewa kwenye pembe maalum ya sterea (kawaida kwenye mhimili wa kati). Hii ni muhimu kwa matumizi ambapo vichunguzi vimewekwa katika nafasi maalum.Total Radiant Flux (mW)是总The integrated power emitted in all directions (over the entire sphere). It represents the total "brightness" of the emitter regardless of direction. A device may have a high total flux but low axial intensity if the light is spread very wide.

9.4 How critical is the one-week usage period after opening the packaging bag?

This is very important for reliable soldering. Plastic packages absorb moisture from the air. During the high-temperature reflow process, this trapped moisture rapidly vaporizes, causing internal delamination, cracking, or "popcorning," which damages the component. The 1-week limit and baking requirements are based on the package's Moisture Sensitivity Level (MSL) to prevent these failures.

10. Practical Design and Application Cases

Case: Designing a Multi-Emitter Object Detection Barrier
A system requires an infrared light curtain to detect objects passing through a 50 cm wide channel. Five pairs of emitter-detector units will be used.

1. Saketi ya kuendesha:Kila kizalishaji kitaendeshwa na MOSFET ya N-channel maalum, ikidhibitiwa na ishara ya PWM ya kidhibiti kidogo ili kurekebisha mwanga wa infrared (kwa mfano, kwa 38kHz). Upinzani wa kuzuia mkondo utahesabiwa kwa kila tawi la LED: R = (V_{Chanzo cha umeme}- V_{F_LED}) / I_F. Kwa kudhani chanzo cha umeme ni 5V, V_F=1.8V, na I_F=500mA (kupunguzwa kwa kuaminika), R = (5 - 1.8) / 0.5 = 6.4Ω (kutumia thamani ya kawaida ya 6.2Ω). Nguvu ya kiwango cha upinzani lazima iwe angalau I²R = (0.5)²*6.2 ≈ 1.55W, kwa hivyo upinzani wa 2W au 3W unahitajika.
2. Thermal Management:Matumizi ya nguvu kwa kila LED P = V_F* I_F= 1.8V * 0.5A = 0.9W. PCB inapaswa kuwa na maeneo makubwa ya shaba yaliyounganishwa kwenye pad za cathode na anode za LED, ili kutumika kama kipenyo cha joto, kudumisha halijoto ya kiungo ndani ya mipaka salama.
3. Ulinganifu wa macho:Pembe ya maono ya 90° hurahisisha uunganishaji na kigunduzi kinacholingana upande wa pili wa pengo. Vifuniko vidogo vya mabomba vinaweza kuwekwa karibu na kiinzaji na kigunduzi, ili kuzuia usumbufu wa mwanga wa mazingira, bila kuzuia mwanga wa boriti kupita kiasi.
4. Ubadilishaji:Tumia wimbi la mraba la 38kHz kuendesha kiinzaji, kuruhusu kigunduzi kulinganishwa na mzunguko sawa, kuchuja kwa ufanisi mwanga wa infrared wa mazingira unaoendelea (kama kutoka kwa jua au taa), na hivyo kuongeza kwa kiasi kikubwa uaminifu wa kugundua.

11. Brief Introduction to Working Principles

This device is a light-emitting diode (LED) that operates in the infrared spectrum. Its core is a semiconductor chip made of gallium arsenide (GaAs). When a forward voltage is applied across the chip's P-N junction, electrons from the N-type material recombine with holes from the P-type material. This recombination process releases energy. In standard silicon diodes, this energy is primarily released as heat. In materials like GaAs, a significant portion of this energy is released as photons (light particles). The specific bandgap of the GaAs material determines the wavelength of these photons, which in this case is centered around 940 nm, placing it in the near-infrared region. The intensity of the emitted light is proportional to the recombination rate, which is controlled by the forward current flowing through the diode.

12. Technology Trends (Objective Perspective)

The field of infrared emitters is evolving alongside broader optoelectronics trends. There is a constant drive towards higher power density and efficiency, allowing for brighter output from smaller packages or with lower power consumption. This enables more compact sensor designs and longer battery life in portable devices. Integration is another key trend, where components combine the emitter, driver circuitry, and sometimes a basic detector or monitor photodiode into a single module or IC package, simplifying system design. Furthermore, advancements in materials, such as developing more efficient epitaxial structures or using new semiconductor compounds, aim to improve performance parameters like electro-optical conversion efficiency (light output per unit of electrical input) and temperature stability. Demand for devices supporting higher modulation speeds also persists, driven by applications in faster data communication and LiDAR (Light Detection and Ranging) systems. These trends focus on enhancing performance, reliability, and ease of use for system designers.