LTE-3273L Infrared Emitter and Detector Datasheet - 940nm Wavelength - High Power - Wide Viewing Angle - Technical Documentation

1. Product Overview

LTE-3273L is a discrete infrared (IR) component, specifically designed for applications requiring reliable infrared light emission and detection. It belongs to a category of optoelectronic devices, engineered to perform in environments where infrared signal transmission is critical. The core functionality of this device is to emit infrared light of a specific wavelength under electrical drive, and/or to detect incoming infrared radiation and convert it into an electrical signal.

This product is positioned to provide solutions for systems that require a balance of high optical output, efficient electrical characteristics, and broad emission/detection patterns. Its design addresses the need for components that operate effectively under pulsed conditions, which is common in digital communication protocols, aiming to save power consumption and enhance signal clarity.

Core Advantages:LTE-3273L distinguishes itself through several key features. It is designed for high-current operation while maintaining a relatively low forward voltage, which helps improve overall electrical efficiency and reduce thermal stress. The device offers high radiant intensity, enabling strong signal transmission over long distances or through obstacles. Its wide viewing angle ensures broad coverage area, making alignment requirements between emitter and detector less stringent in system design. Finally, the transparent package allows maximum light transmission while minimizing internal absorption or scattering.

Target Markets and Applications:This component is primarily targeted at consumer electronics, industrial automation, and security fields. Its typical applications include, but are not limited to: infrared remote controls for TVs and audio equipment, short-range wireless data transmission links, proximity sensors, object counters, and security alarm systems that detect beam interruption. Its high-speed capability also makes it suitable for basic infrared data communication protocols.

2. In-depth Technical Parameter Analysis

This section provides a detailed and objective interpretation of the key parameters listed in the datasheet, explaining their significance for design and application.

2.1 Absolute Maximum Ratings

These ratings define the stress limits that may cause permanent damage to the device. Operation at or near these limits is not recommended to ensure reliable, long-term performance.

• Power Dissipation (Pd): 150 mW- This is the maximum power the device can dissipate as heat when the ambient temperature (TA) is 25°C. Exceeding this limit risks overheating and damaging the semiconductor junction, leading to accelerated degradation or catastrophic failure. Designers must ensure the power dissipation (IF * VF) generated by the operating conditions (forward current and voltage) remains below this value, with an appropriate margin.
• Peak Forward Current (I_FP): 2 A- Iri ne ƙarfin lantarki mafi girma da ake ba da izinin aiki da bugun jini, an ƙayyade shi a cikin daƙiƙa 300 na bugun jini (pps), faɗin bugun jini 10 µs. Wannan babban ƙimar ƙima yana ba na'urar damar samar da fitowar haske mai ƙarfi sosai a cikin ɗan gajeren bugun jini, yana dacewa sosai don sarrafa nesa mai nisa ko bugun sigina mai ƙarfi a cikin yanayi mai hayaniya.
• Ci gaba da ƙarfin lantarki na gaba (I_F): 100 mA- Wannan shine mafi girman ƙarfin lantarki na DC da za'a iya amfani dashi akai-akai. Don yawancin aikace-aikacen haske na yau da kullun, dole ne a kiyaye ƙarfin aiki a wannan matakin ko ƙasa da shi. Yawanci ƙarfin aiki yana da ƙasa sosai (misali 20-50 mA), don tabbatar da tsawon rayuwa da sarrafa zafi.
• Reverse Voltage (V_R): 5 V- The maximum reverse voltage that can be applied across the LED. Exceeding this value may cause breakdown and damage the device. Circuit protection measures such as series resistors or parallel protection diodes are typically used to prevent reverse voltage spikes.
• Operating and Storage Temperature Range:The operating temperature rating of this device ranges from -40°C to +85°C, and the storage temperature range is from -55°C to +100°C. These wide ranges make it suitable for applications such as automotive, industrial, and outdoor environments where extreme temperatures may be encountered.
• Pin soldering temperature: 260°C for 5 seconds.- This defines the tolerance for the reflow soldering profile. The specification of 1.6mm from the body is critical; applying heat closer to the plastic package may cause deformation or internal damage.

2.2 Electrical and Optical Characteristics

These are typical performance parameters measured under specified test conditions (TA=25°C). They define the behavior of the device in a circuit.

• Radiant Intensity (I_E):
  • 5.6 - 8.0 mW/sr @ I_F= 20mA- This is the light power emitted per unit solid angle (steradian). It is a direct indicator for measuring the "brightness" of an IR light source from the front. This range represents typical unit-to-unit variation.
  • 28.0 - 40.0 mW/sr @ I_F= 100mA- Shows a nonlinear relationship between current and output. A fivefold increase in current results in approximately a fivefold increase in radiation intensity, indicating good efficiency even at higher currents.
• Peak emission wavelength (λ_Peak): 940 nm- Wavelength at which the device emits maximum optical power. 940nm belongs to the near-infrared spectrum and is invisible to the human eye. This is a common wavelength for remote controls because it avoids visible red light and matches well with the sensitivity characteristics of silicon photodetectors.
• Spectral Line Half-Width (Δλ): 50 nm- This parameter is also known as Full Width at Half Maximum (FWHM), indicating the spectral purity of the emitted light. A value of 50 nm means the emitted light covers a wavelength band centered around the 940nm peak with a width of approximately 50nm. This is typical for standard GaAs infrared emitting diodes.
• Forward Voltage (V_F):
  • 1.25 - 1.6 V @ I_F= 50mA- The voltage drop across the device when conducting a current of 50mA. This low V_Fis a key characteristic that reduces power loss and heat generation.
  • 1.85 - 2.3 V @ I_F= 500mA- V_F The voltage drop increases with current due to the internal resistance of the diode. This value is crucial for designing high-current pulse drivers.
• Reverse current (I_R): Max. 100 µA @ V_R= 5V- The small leakage current that flows when the maximum reverse voltage is applied. Ideally, this value should be low.
• Viewing angle (2θ_1/2): 40°- Ee n'ọkụ nke ike radieshon na-agbadata ruo ọkara nke uru ya kachasị elu (axial). Nkuku 40° na-enye ìhè sara mbara nke ọma, dabara adaba maka ngwa ndị siri ike idozi nke ọma.

2.3 Thermal Characteristics

Ọ bụ ezie na edepụtaghị ya n'ụzọ doro anya na tebụl dị iche, enwere ike ịchọpụta omume okpomọkụ site na ọtụtụ paramita. Oke oriri ike (150mW) bụ n'ezie oke okpomọkụ. Usoro arụmọrụ (nke a ga-atụle ma emechaa) na-egosi otu mmepụta na voltaji na-aga n'ihu si agbanwe dabere na okpomọkụ gburugburu ebe obibi. Nlekọta okpomọkụ dị irè (site na mpaghara ọla kọpa PCB ma ọ bụ ihe na-ekpo ọkụ) dị oke mkpa maka idobe arụmọrụ na ntụkwasị obi, ọkachasị mgbe a na-arụ ọrụ nso oke iyi na-aga n'ihu.

3. Performance Curve Analysis

Typical curves provide visual and quantitative insight into a device's behavior under different conditions, which is essential for robust circuit design.

3.1 Forward Current vs. Forward Voltage (Figure 3)

This IV curve shows the typical exponential relationship of a diode. At low currents, the voltage is low. As the current increases, the voltage rises. This curve allows designers to select an appropriate current-limiting resistor for a given power supply voltage. For example, to drive an LED from a 5V supply at 100mA, the resistor value R = (V_supply- V_F) / I_F. Using typical V at 100mA_F approximately 1.6V (extrapolated), R will be (5 - 1.6) / 0.1 = 34 ohms. Power in the resistor is I²R = 0.34W.

3.2 Relative Radiant Intensity vs. Forward Current (Figure 5)

This graph illustrates the dependence of light output on drive current. It is typically linear at lower currents, but at very high currents, it may show signs of saturation or reduced efficiency due to thermal effects and internal quantum efficiency. The curve confirms that pulsed operation at 2A (from Absolute Maximum Ratings) will yield a much higher instantaneous output than continuous 100mA operation, demonstrating its utility in long-distance signaling.

3.3 Relative Radiant Intensity vs. Ambient Temperature (Figure 4)

This is the key curve for understanding environmental impact. It shows that radiant intensity decreases as ambient temperature increases. This is a characteristic of LEDs; higher junction temperature reduces internal quantum efficiency. For example, the output at +85°C may be only 60-70% of the output at +25°C. Designers must account for this derating in systems that must operate reliably across the entire temperature range. This may require driving the LED at a slightly higher current at high temperatures to compensate for the lost light output, provided the power dissipation limits are not exceeded.

3.4 Spectral Distribution (Figure 1)

This figure visualizes the emission spectrum, centered at 940nm with an FWHM of 50nm. It confirms the device's emission in the near-infrared region and aids in selecting compatible optical filters or assessing potential interference from ambient light sources, such as sunlight or incandescent bulbs with broad spectra.

3.5 Radiation Pattern (Figure 6)

This polar plot provides a detailed view of the angular distribution of the emitted light. It graphically represents the 40° viewing angle (2θ_1/2). The shape of the curve is crucial for designing lenses or reflectors to collimate or further diffuse the beam to suit specific applications.

4. Mechanical and Packaging Information

4.1 Outline Dimensions and Tolerances

The device employs a standard through-hole package with a flange to provide mechanical stability and potential heat dissipation. Key dimensions include body diameter, lead pitch, and overall length. All dimensions are specified in millimeters. Unless otherwise noted for specific features, the standard tolerance is ±0.25mm. Lead pitch is measured at the point where the leads exit the package body, which serves as the standard reference for PCB hole placement. The maximum resin protrusion beneath the flange is 1.5mm, which is important for PCB standoff height and cleaning.

4.2 Polarity Identification

For infrared emitters (LEDs), the longer lead is typically the anode (positive), and the shorter lead is the cathode (negative). The outline drawing in the datasheet should clearly indicate this, usually with a flat on the package or a notch near the cathode lead. Correct polarity is crucial; a reverse bias exceeding 5V can damage the device.

5. Welding and Assembly Guide

Reflow Soldering:The specified parameter is 260°C for a maximum of 5 seconds, measured at a point 1.6mm from the package body. This aligns with common lead-free reflow profiles (peak temperature 240-260°C). The 1.6mm distance is critical to prevent the plastic package from exceeding its glass transition temperature and deforming.

Hand soldering:If hand soldering must be performed, a temperature-controlled soldering iron should be used. The contact time per pin should be minimized, ideally less than 3 seconds, with a heat sink clip applied to the pin between the iron and the package body.

TsabAfter welding, standard PCB tsab processes can be used, but the compatibility of the cleaning agent with the transparent resin encapsulation should be verified.

Storage conditions:To prevent moisture absorption (which may cause "popcorn" phenomenon during reflow soldering), devices should be stored in a dry environment, typically with relative humidity below 40% at room temperature, or if storage is extended, in a sealed moisture barrier bag with desiccant.

6. Application Suggestions and Design Considerations

6.1 Typical Application Circuit

Transmitter Drive Circuit:The simplest circuit is a series current-limiting resistor. For pulsed operation, a transistor (BJT or MOSFET) is used to switch high currents. The driver must be capable of supplying the peak current (up to 2A) with a low saturation voltage drop to maximize the voltage across the LED. For data transmission, fast rise/fall times are required.

Detector Circuit:When used as a photodiode (if applicable according to the model), it typically operates in reverse bias or photovoltaic (zero-bias) mode, connected to a transimpedance amplifier to convert small photocurrents into usable voltages.

6.2 Key Design Considerations

• Current Limiting:Always use a series resistor or an active constant current driver. Never connect directly to a voltage source.
• Pulse operation:For pulsed drive, ensure the pulse width and duty cycle keep the average power dissipation within limits. Average current = Peak current * Duty cycle. For a 2A pulse at 300pps, 10µs width, duty cycle = (10e-6 * 300) = 0.003 (0.3%). Average current = 2A * 0.003 = 6mA, which is well within the continuous rating.
• Optical path:Considering a 40° field of view. For a focused beam, a lens may be required. For wide-area detection, this angle may be sufficient. Keep the optical path unobstructed and clean.
• Resistance to Ambient Light Interference:In detector applications, ambient infrared light (from the sun, lamps) is the primary noise source. Using a modulated infrared signal (e.g., 38kHz) and a corresponding tuned receiving circuit is the standard method to suppress this DC and low-frequency noise.
• PCB Layout:For the transmitter, ensure sufficient trace width to handle peak pulse current without excessive voltage drop. For thermal management, connect the flange (if electrically isolated or connected to the pin) to a copper foil area on the PCB as a heat sink.

7. Technical Comparison and Differentiation

Although specific competitor models are not mentioned, the parameter combination of LTE-3273L defines its positioning:

• Compared to standard 940nm infrared emitting diodes:Its high peak current rating (2A) and high radiant intensity at 100mA distinguish it from low-power models used in simple remote controls. This makes it suitable for applications requiring longer distances or higher noise immunity.
• Compared to high-speed 850nm infrared emitting diodes:LTE-3273L uses GaAs material and operates at 940nm, while high-speed models typically use AlGaAs material and operate at 850nm. 850nm devices usually have faster rise/fall times for high-speed data, but may have a faint red glow. 940nm devices are completely invisible, which is preferable for covert applications, and their 50nm full width at half maximum is standard.
• Compared to phototransistors/photodiodes in the same package:The datasheet title indicates that this series covers both emitters and detectors. The dedicated photodetector version will have different characteristics (responsivity, dark current, speed). A key advantage of a matched pair from the same series is the potential for optimized spectral matching.

8. Frequently Asked Questions (Based on Technical Parameters)

Q1: Can I drive this LED continuously with 500mA?
A: No. The absolute maximum rating for continuous forward current is 100mA. The 500mA condition listed in the electrical characteristics table is for measuring V under high current._F The test conditions may be related to its pulse operation rating. Continuous operation must not exceed 100mA.

Q2: Why does the range of my infrared remote control shorten in a hot car?
A: Please refer to Figure 4 (Relative Radiant Intensity vs. Ambient Temperature). The LED's output decreases as the temperature rises. At +85°C, the output may be 30-40% lower than at room temperature, directly reducing the effective range.

Q3: When using a 3.3V power supply, what size resistor should I use to achieve the typical output?
A: For a target I_F of 20mA (producing 5.6-8.0 mW/sr), and with a typical V_F of 1.6V at 50mA (estimated at about 1.5V for 20mA), R = (3.3V - 1.5V) / 0.02A = 90 ohms. The closest standard value is 91 ohms. Power in the resistor: (0.02^2)*91 = 0.0364W, so a 1/8W or 1/10W resistor is sufficient.

Q4: Is the viewing angle the same for emission and detection?
A: For an infrared emitter (LED), the 40° angle specifies the emission pattern. For a photodiode or phototransistor detector, a similar but separate parameter called the "field of view" or "sensitivity angle" defines its angular acceptance range. They are typically similar but not necessarily identical. Consult the specific detector datasheet.

9. Practical Design and Usage Cases

Case: Design a long-range garage door opener transmitter.
The design goal is to achieve a reliable 50-meter range under daylight conditions. The LTE-3273L was selected for its high pulse output capability.
Design Steps:
1. Circuitu mai gudanarwa:Yi amfani da MOSFET wanda microcontroller ke sarrafawa don fitar da LED ta hanyar bugun jini. Yi lissafin resistor a jere bisa ga ƙarfin baturi (misali 12V) da kuma ƙimar kololuwar halin yanzu da ake buƙata. Don ƙara nisa, fitar da kusa da ƙimar kololuwar ƙima: zaɓi I_FP= 1.5A (within the maximum of 2A). V at 1.5A_F(extrapolated from the curve) approximately 2.5V. Resistance R = (12V - 2.5V) / 1.5A = 6.33 ohms. Use a 6.2 ohm, 5W resistor to handle the pulse power (P = I²R = 1.5^2 * 6.2 ≈ 14W peak, but the average power is very low).
2. Pulse modulation:Commands are encoded using a 38kHz carrier modulated by data bits. The pulse width of each 38kHz burst is kept at 10µs or less to stay within the rated value. The duty cycle is very low.
3. Optical:A simple plastic lens is added in front of the LED to collimate the natural 40° beam into a narrower, more focused beam for longer distance.
4. Thermal Management:Due to the low duty cycle, the average power and heat generation are extremely small. No special heat sink is required other than the PCB copper foil connected to the flange.
This design leverages the key characteristics of the LTE-3273L: high peak current, high radiant intensity, and suitability for pulsed operation.

10. Introduction to Working Principles

Infrared Emitter (IRED):LTE-3273L, when functioning as an emitter, is a light-emitting diode (LED) based on gallium arsenide (GaAs) semiconductor material. When a forward voltage is applied, electrons and holes are injected into the active region of the semiconductor junction. When these charge carriers recombine, they release energy in the form of photons (light). The specific bandgap energy of the GaAs material determines the wavelength of these photons, which is in the infrared region of 940 nanometers. The transparent package allows this light to escape with minimal loss.

Infrared Detector (Photodiode):If configured as a detector, the device contains a semiconductor PIN junction. When photons with energy greater than the semiconductor bandgap (i.e., infrared light) strike the depletion region, they generate electron-hole pairs. These charge carriers are then separated by the built-in electric field (or an applied reverse bias), producing a photocurrent proportional to the intensity of the incident light. This small current can be amplified and processed by external circuitry.

11. Technical Trends and Background

Discrete infrared components like the LTE-3273L represent a mature and stable technology. Core materials (GaAs, AlGaAs) and package types have been optimized over decades for reliability and cost-effectiveness. The ongoing trend in this field is not revolutionary changes to the discrete devices themselves, but rather their integration and application context:

• Integration:There is a trend towards integrated modules that combine emitters, detectors, drivers, amplifiers, and digital logic (such as decoders for specific protocols) into a single surface-mount package. These simplify design but may not offer the same level of customization or performance optimization as discrete components for specialized applications.
• Miniaturization:While through-hole packages remain popular for their robustness, there is a growing demand for smaller surface-mount device (SMD) versions to save space on modern PCBs.
• Performance Enhancement:For new applications such as consumer electronics LiDAR or advanced gesture recognition, faster and more efficient infrared emitters (e.g., using VCSEL technology) and detectors with higher sensitivity and lower noise are being researched. However, for classic applications like remote controls, proximity sensing, and basic data links, traditional components like the LTE-3273L offer the best balance between performance, reliability, and cost.
• Application Expansion:Its fundamental principles remain relevant for emerging Internet of Things (IoT) devices, which require simple, low-power wireless communication or sensing without the complexity of radio frequency (RF) systems.

In summary, LTE-3273L is a component based on mature technology, with clear specifications and robust durability. Its value lies in its clear, detailed datasheet, which enables engineers to accurately predict its behavior and effectively design it into systems requiring reliable infrared functionality for control, sensing, or basic communication.