LTE-1252 IR Emitter and Detector Datasheet - 940nm Wavelength - 100mA Forward Current - 1.53V Typical Forward Voltage - 5.0x3.8x3.5mm Package - English Technical Documentation

1. Product Overview

LTE-1252 ni kifaa tofauti cha infrared (IR) emitter kilichoundwa kwa matumizi mbalimbali ya optoelectronic. Inafanya kazi kwenye urefu wa wimbi la kilele cha 940nm, na hufanya iweze kutumika katika mazingira ambapo mwanga unaoonekana haupendekezwi. Kifaa hiki kimeundwa kwa kifurushi cha plastiki wazi, na kinatoa pembe ya kuona pana. Kina sifa ya ukubwa wa mionzi na uwezo wa kufanya kazi kwa mkondo mkubwa na voltage ya mbele ya chini.

1.1 Sifa Muhimu

• Muundo usio na Lead (Pb) na unaolingana na RoHS.
• Optimized for high current and low forward voltage operation.
• Low-cost miniature plastic end-looking package.
• Wide viewing angle for broad coverage.
• High radiant intensity output.
• Clear transparent package.

1.2 Matumizi ya Lengwa

• Infrared emitters for remote control units.
• Sensor systems for proximity or object detection.
• Night vision illumination in security systems.
• IR wireless data transmission links.
• Security alarm systems.

2. Technical Parameter Deep Dive

This section provides a detailed, objective interpretation of the key electrical and optical parameters specified for the LTE-1252 IR emitter.

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed.

• Power Dissipation (Pd): 150 mW. This is the maximum power the device can dissipate as heat at an ambient temperature (TA) of 25°C. Exceeding this limit risks thermal damage.
• Peak Forward Current (IFP): 1 A. This is the maximum allowable pulsed current under specific conditions (300 pulses per second, 10μs pulse width). It is significantly higher than the continuous current rating, allowing for brief, high-intensity bursts.
• Continuous Forward Current (IF): 100 mA. The maximum DC current that can be applied continuously without damaging the device.
• Reverse Voltage (VR): 5 V. The maximum voltage that can be applied in the reverse direction. The datasheet explicitly notes this condition is for test only, and the device is not designed for reverse operation.
• Operating Temperature Range (Topr): -40°C to +85°C. The ambient temperature range over which the device is specified to operate.
• Storage Temperature Range (Tstg): -55°C to +100°C. The temperature range for non-operational storage.
• Lead Soldering Temperature: 260°C for 5 seconds, measured 2.0mm from the body. This defines the hand-soldering thermal profile limit.

2.2 Electrical & Optical Characteristics

These are the typical and guaranteed performance parameters measured at TA=25°C and under specified test conditions.

• Radiant Intensity (Ie): 40 mW/sr (Min), 70 mW/sr (Typ) at IF=100mA, θ=0°. This measures the optical power emitted per unit solid angle along the central axis, indicating brightness.
• Peak Emission Wavelength (λPeak): 940 nm (Typ) at IF=100mA. The wavelength at which the emitted optical power is maximum.
• Spectral Line Half-Width (Δλ): 54 nm (Typ) at IF=100mA. This parameter defines the spectral bandwidth; a value of 54nm indicates the emitted light is not monochromatic but spans a range of wavelengths around the peak.
• Forward Voltage (VF): 1.30V (Min), 1.53V (Typ), 1.83V (Max) at IF=100mA. The voltage drop across the device when conducting the specified forward current. Lower VF generally leads to higher efficiency.
• Reverse Current (IR): 100 μA (Max) at VR=5V. The small leakage current that flows when the specified reverse voltage is applied.
• Value Angle (θ0.5): 40° (Typ). The viewing angle where the radiant intensity drops to half of its value at 0°. A 40° angle provides a reasonably broad emission pattern.

3. Performance Curve Analysis

The typical characteristic curves provide visual insight into device behavior under varying conditions.

3.1 Spectral Distribution (Fig.1)

The curve shows the relative radiant intensity as a function of wavelength. It confirms the peak at 940nm and the spectral half-width, illustrating that the emitter outputs infrared light primarily within the 880nm to 1000nm range.

3.2 Forward Current vs. Ambient Temperature (Fig.2)

This graph depicts the derating of the maximum allowable forward current as ambient temperature increases. It is crucial for thermal management design to ensure the device operates within its safe operating area (SOA).

3.3 Forward Current vs. Forward Voltage (Fig.3)

The IV curve shows the exponential relationship between current and voltage, typical of a diode. The curve allows designers to determine the required drive voltage for a desired operating current.

3.4 Relative Radiant Intensity vs. Ambient Temperature (Fig.4) & vs. Forward Current (Fig.5)

Figure 4 shows how optical output decreases with increasing temperature for a fixed current. Figure 5 shows the near-linear increase in output with increasing forward current, highlighting the current-controlled nature of LEDs.

3.5 Radiation Diagram (Fig.6)

This polar plot visually represents the spatial distribution of emitted light, confirming the 40° half-value angle and showing the intensity pattern, which is important for aligning the emitter with a detector.

4. Mechanical & Package Information

4.1 Outline Dimensions

The device uses a through-hole package with the following key dimensions (in mm, nominal):

• Overall Length: 24.0 MIN
• Body Width: 5.0 ±0.3
• Body Height: 3.8 ±0.3
• Lens Diameter/Height: 3.5 ±0.3
• Lead Spacing: 2.54 NOM (standard 0.1" pitch)
• Lead Diameter: 0.5 (protruded resin under flange max)

Polarity Identification: The longer lead is the anode (+), and the shorter lead is the cathode (-). The diagram also shows a flat side on the lens, which may serve as an additional visual marker.

4.2 Critical Notes

• Tolerance is ±0.25mm unless otherwise specified.
• Lead spacing is measured where leads emerge from the package body.
• Manufacturing sites are indicated.

5. Assembly, Soldering & Handling Guidelines

5.1 Lead Forming & PCB Assembly

• Bend leads at a point at least 3mm from the base of the LED lens.
• Do not use the package base as a fulcrum during bending.
• Fanya umbo la risasi kabla ya kuuza, kwa joto la kawaida.
• Tumia nguvu ya chini ya kufunga wakati wa usanikishaji wa PCB ili kuepuka mkazo wa mitambo.

5.2 Mchakato wa Kuuza

Hand Soldering (Iron):

• Temperature: 350°C Max.
• Time: 3 seconds Max. (one time only).
• Position: No closer than 2mm from the base of the epoxy lens.

Wave Soldering:

• Pre-heat: 100°C Max. for 60 seconds Max.
• Solder Wave: 260°C Max.
• Soldering Time: 5 seconds Max.
• Dipping Position: No lower than 2mm from the base of the epoxy lens.

Critical Warning: Excessive temperature or time can deform the lens or cause catastrophic failure. IR reflow is NOT suitable for this through-hole package type.

5.3 Storage & Cleaning

• Storage: Do not exceed 30°C or 70% relative humidity. Use within 3 months if removed from original packaging. For extended storage, use a sealed container with desiccant or a nitrogen ambient.
• Cleaning: Use alcohol-based solvents like isopropyl alcohol if necessary.

6. Application Design Considerations

6.1 Drive Circuit Design

An LED is a current-operated device. To ensure uniform brightness when driving multiple LEDs in parallel, it is strongly recommended to use a individual current-limiting resistor in series with each LED (Circuit Model A). Using a single resistor for multiple parallel LEDs (Circuit Model B) is discouraged due to variations in the forward voltage (I-V characteristics) of individual devices, which will lead to uneven current distribution and thus uneven brightness.

6.2 Electrostatic Discharge (ESD) Protection

The device is susceptible to damage from static electricity. Preventive measures include:

• Using conductive wrist straps or anti-static gloves.
• Ensuring all equipment, workstations, and storage racks are properly grounded.
• Using ion blowers to neutralize static charge on the plastic lens.
• Maintaining ESD-certified personnel and static-safe work areas (surfaces <100V).

6.3 Application Scope & Reliability

The device is intended for ordinary electronic equipment (office, communication, household). For applications requiring exceptional reliability where failure could jeopardize life or health (aviation, medical, safety systems), specific consultation and qualification are necessary prior to use.

7. Technical Principles & Trends

7.1 Operating Principle

The LTE-1252 is an Infrared Emitting Diode (IRED). When a forward voltage exceeding its threshold is applied, electrons and holes recombine in the semiconductor's active region (likely based on GaAs or AlGaAs material), releasing energy in the form of photons. The specific material composition and device structure are engineered to produce photons primarily in the 940nm infrared range, which is invisible to the human eye but easily detected by silicon photodiodes and many camera sensors.

7.2 Industry Context & Trends

Discrete IR components like the LTE-1252 remain fundamental building blocks in optoelectronics. Key trends influencing this sector include the continued demand for miniaturization, higher efficiency (more radiant intensity per mA), and tighter integration with sensing ICs. There is also a growing emphasis on devices compliant with environmental regulations (RoHS, lead-free). The 940nm wavelength is particularly popular as it offers a good balance between silicon detector sensitivity and lower visibility compared to 850nm sources, making it ideal for covert illumination in security and consumer applications like remote controls.

8. Frequently Asked Questions (FAQ)

8.1 Can I drive this IR LED directly from a microcontroller pin?

No. A microcontroller GPIO pin typically cannot source 100mA continuously. You must use a transistor (e.g., NPN BJT or N-channel MOSFET) as a switch, controlled by the GPIO, to provide the necessary current from the power supply. A series current-limiting resistor is still required in the LED path.

8.2 Yaya ake lissafin darajar resistor na jerin?

Yi amfani da Dokar Ohm: R = (Vcc - VF) / IF. Misali, tare da wadatar Vcc=5V, VF na yau da kullun=1.53V a 100mA, resistor zai kasance R = (5 - 1.53) / 0.1 = 34.7 Ohms. Yi amfani da mafi kusancin darajar da aka saba (misali, 33 ko 39 Ohms) kuma duba ƙimar wutar lantarki: P = (IF)^2 * R = (0.1)^2 * 34.7 ≈ 0.347W, don haka ana ba da shawarar resistor na 0.5W ko mafi girma.

8.3 Me yasa ƙimar ƙarfin lantarki na baya kawai 5V, kuma me zai faru idan na wuce shi?

IR LEDs ba a ƙera su don toshe babban ƙarfin juyawa ba. Wucewa da ƙimar 5V na iya haifar da haɓakar kwararar juyawa kwatsam, wanda ke haifar da rushewar dusar ƙanƙara da lalata dindindin na haɗin semiconductor. Koyaushe tabbatar da daidaitaccen polarity a cikin da'irar ku. Don kariya ta bidirectional a cikin AC ko yanayi mara tabbas na polarity, ya kamata a yi amfani da diode na kariya na waje.

8.4 Takardar bayanan ta ambaci "value angle" na 40°. Ta yaya wannan ke shafar ƙirar ta?

The 40° half-value angle means the emitted light intensity is strongest in the center and falls to 50% at ±20° from the center axis. When aligning the emitter with a detector (like a phototransistor), you must ensure the detector is within this effective cone of radiation. For wider coverage, you may need multiple emitters or a diffuser. Conversely, for long-range, directed beams, a lens may be added to collimate the light.

9. Practical Design Case Study

9.1 Simple Object Detection / Break-Beam Sensor

Scenario: Detect when an object passes between an IR emitter and a detector.

Implementation:

1. Emitter Side: Drive the LTE-1252 with a constant current of 50-100mA using a circuit as described in section 6.1. For battery operation, consider pulsing the LED at a specific frequency (e.g., 1kHz, 50% duty cycle) to save power.
2. Detector Side: Use a matching phototransistor or photodiode aligned with the emitter. Place it within the emitter's 40° radiation cone.
3. Signal Conditioning: The detector's output will be high when receiving IR light and drop when the beam is blocked. Use a comparator or a microcontroller's ADC input to digitize this signal. If the emitter is pulsed, add a filter or synchronous detection in software to reject ambient light noise.

Key Considerations: Alignment is critical due to the directional nature of the beam. Ambient sunlight or other IR sources can cause interference, so modulation/demodulation techniques are highly recommended for reliable operation. Ensure the housing blocks stray light from hitting the detector directly without passing through the detection zone.