IR Emitter and Detector LTLE-32F0L-032A Datasheet - T-1 3/4 Package - 850nm Wavelength - 1.95V Forward Voltage - 180mW Power Dissipation - English Technical Document

1. Product Overview

This document details the specifications for a discrete infrared (IR) emitter and detector component. The device is designed for applications requiring infrared light emission and detection, operating at a peak wavelength of 850 nanometers (nm). It is housed in a popular T-1 3/4 diameter package with clear transparent encapsulation, making it suitable for a variety of optoelectronic systems.

1.1 Core Advantages and Target Market

The component offers several key advantages including high-speed operation, low power consumption, and high efficiency. It is compliant with lead-free (Pb-free) and RoHS environmental standards. Its primary applications include use as an 850nm IR emitter, integration into night vision systems for cameras, and various sensor applications where infrared light is used for proximity sensing, data transmission, or object detection.

2. Technical Parameter Deep Dive

The following sections provide a detailed, objective interpretation of the device's key parameters.

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. They are specified at an ambient temperature (TA) of 25°C.

• Power Dissipation (Pd): 180 mW. This is the maximum amount of power the device can dissipate as heat without exceeding its thermal limits.
• Peak Forward Current (IFP): 1 A. This is the maximum allowable current under pulsed conditions (300 pulses per second, 10μs pulse width). Exceeding this can cause catastrophic failure.
• Continuous Forward Current (IF): 100 mA. The maximum DC current that can be applied continuously.
• Reverse Voltage (VR): 5 V. Applying a reverse voltage higher than this can break down the semiconductor junction.
• Operating Temperature Range: -40°C to +85°C. The ambient temperature range within which the device is guaranteed to operate according to its specifications.
• Storage Temperature Range: -55°C to +100°C.
• Lead Soldering Temperature: 320°C for 3 seconds, measured 4.0mm from the body of the component.

2.2 Electrical and Optical Characteristics

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

• Radiant Intensity (I_E): 28 mW/sr (typical). This measures the optical power emitted per unit solid angle (steradian) when driven at a forward current (I_F) of 50mA. It is a key metric for the emitter's brightness.
• Peak Emission Wavelength (λ_Peak): 850 nm. The wavelength at which the emitter outputs the most optical power. This is in the near-infrared spectrum, invisible to the human eye but detectable by silicon photodiodes and many camera sensors.
• Spectral Line Half-Width (Δλ): 50 nm. This indicates the spectral bandwidth; the range of wavelengths over which significant optical power is emitted. A value of 50nm is typical for standard GaAs/AlGaAs IR emitters.
• Forward Voltage (V_F): 1.6V (Min), 1.95V (Typ), unspecified Max at I_F=50mA. This is the voltage drop across the device when conducting current. It is crucial for designing the current-limiting driver circuit.
• Reverse Current (I_R): 100 μA (Max) at V_R=5V. The small leakage current that flows when the device is reverse-biased.
• Viewing Angle (2θ_1/2): 60 degrees. This is the full angle at which the radiant intensity drops to half of its maximum value (on-axis). It defines the beam spread of the emitted light.

3. Performance Curve Analysis

The datasheet provides several characteristic curves that illustrate device behavior under varying conditions.

3.1 Spectral Distribution

Figure 1 shows the relative radiant intensity as a function of wavelength. The curve is centered at 850nm with the specified 50nm half-width, confirming the spectral characteristics. This information is vital for ensuring compatibility with the spectral sensitivity of the intended detector (e.g., a silicon photodiode or a camera's IR filter).

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

Figure 3 depicts the relationship between forward current and forward voltage. This curve is exponential in nature, typical for a diode. It shows that the forward voltage increases with current. Designers use this curve to select an appropriate current-limiting resistor to achieve the desired operating point (e.g., 50mA for the specified radiant intensity) without exceeding the maximum ratings.

3.3 Temperature Dependence

Figures 2 and 4 illustrate the effects of ambient temperature on device performance.

• Forward Current vs. Ambient Temperature (Fig. 2): Likely shows how the forward voltage at a fixed current decreases as temperature increases (negative temperature coefficient), a common trait in LEDs.
• Relative Radiant Intensity vs. Ambient Temperature (Fig. 4): Demonstrates that the optical output power of the emitter decreases as the ambient temperature rises. This derating is critical for applications operating in high-temperature environments; the drive current may need to be increased (within limits) to maintain a constant light output, or thermal management may be required.

3.4 Relative Radiant Intensity vs. Forward Current

Figure 5 shows how the optical output power increases with drive current. This relationship is generally linear over a range but will eventually saturate at very high currents due to thermal and efficiency limits. Operating near the typical 50mA point ensures good efficiency and longevity.

3.5 Radiation Diagram

Figure 6 is a polar plot showing the angular distribution of the emitted light intensity, visually representing the 60-degree viewing angle. The intensity is highest along the central axis (0°) and diminishes towards the edges.

4. Mechanical and Packaging Information

4.1 Outline Dimensions

The device uses a standard T-1 3/4 (5mm) round package. Key dimensional notes include: all dimensions in mm (inches), a tolerance of ±0.25mm unless stated, a maximum resin protrusion under the flange of 0.5mm, and lead spacing measured at the package exit point. The exact mechanical drawing provides critical information for PCB footprint design, ensuring proper fit and alignment.

4.2 Tape and Reel Packaging Dimensions

For automated assembly, the components are supplied on embossed carrier tape. Section 6 provides a detailed table of tape dimensions including feed hole diameter (D: 3.8-4.2mm), component pitch (P: 12.5-12.9mm), pocket dimensions (P1, P2, H), and tape width (W3: 17.5-19.0mm). Adhesive tape (width W1: 12.5-13.5mm) seals the components in the pockets. These specifications are essential for programming pick-and-place machines and designing feeder systems.

5. Soldering and Assembly Guidelines

Proper handling is crucial for reliability.

5.1 Storage

Components should be stored at ≤30°C and ≤70% relative humidity. If removed from the original moisture-barrier bag, they should be used within three months. For longer storage outside the bag, use a sealed container with desiccant or a nitrogen desiccator to prevent moisture absorption, which can cause \"popcorning\" during soldering.

5.2 Cleaning

If cleaning is necessary, use alcohol-based solvents like isopropyl alcohol. Harsh chemicals may damage the epoxy lens.

5.3 Lead Forming

Bend leads at a point at least 3mm from the base of the lens. Do not use the package body as a fulcrum. Forming must be done at room temperature and before soldering. Use minimal force during PCB insertion to avoid stress.

5.4 Soldering Parameters

Maintain a minimum 3mm clearance from the lens base to the solder point. Never immerse the lens in solder.

• Soldering Iron: Max 350°C for max 3 seconds (one time only).
• Wave Soldering: Pre-heat ≤100°C for ≤60 sec, solder wave ≤320°C for ≤3 sec. The dipping position must be no lower than 2mm from the lens base.
• Important Note: Excessive temperature or time can deform the lens or destroy the device. Infrared (IR) reflow is NOT suitable for this through-hole component.

6. Application and Design Considerations

6.1 Drive Circuit Design

This is a current-operated device. To ensure uniform brightness when driving multiple emitters in parallel, a current-limiting resistor must be placed in series with each individual LED (Circuit A). Simply connecting LEDs in parallel with a single shared resistor (Circuit B) is not recommended due to variances in the forward voltage (V_F) of each device, which will cause uneven current distribution and thus uneven brightness.

6.2 Electrostatic Discharge (ESD) Protection

The component is sensitive to ESD and power surges. Preventive measures are mandatory:

• Use grounded wrist straps and anti-static gloves.
• Ensure all equipment, workstations, and storage racks are properly grounded.
• Use ionizers to neutralize static charge that may build up on the plastic lens.

6.3 Application Scope and Reliability

The device is intended for ordinary electronic equipment (office, communications, household). For applications where failure could jeopardize life or health (aviation, medical, safety systems), special consultation and qualification are required prior to use, as the standard reliability data may not suffice for such critical uses.

7. Technical Comparison and Trends

7.1 Differentiation

The 850nm wavelength offers a balance between good silicon detector sensitivity and lower absorption in many materials compared to longer IR wavelengths. The T-1 3/4 package is a industry-standard, ensuring wide compatibility with sockets and PCB layouts. The clear lens (as opposed to tinted) maximizes light output for the emitter function.

7.2 Operating Principle

As an IR Emitter (IRED): When forward-biased above its threshold voltage, electrons and holes recombine in the semiconductor active region (likely GaAs/AlGaAs), releasing energy in the form of photons at the characteristic 850nm wavelength. The clear epoxy lens shapes and directs this light output.

As a Detector (Photodiode): When photons with sufficient energy strike the semiconductor junction, they generate electron-hole pairs, creating a photocurrent when the device is reverse-biased. This current is proportional to the incident light intensity.

7.3 Design Trends

The industry continues to drive for higher efficiency (more light output per electrical watt), improved speed for data transmission, and enhanced reliability. Surface-mount device (SMD) packages are increasingly common for automated assembly, though through-hole packages like this one remain vital for prototyping, high-power applications, or scenarios requiring robust mechanical mounting.

8. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED directly from a 5V or 3.3V microcontroller pin?
A: No. You must use a series current-limiting resistor. For example, to achieve 50mA from a 5V supply with a typical V_F of 1.95V: R = (5V - 1.95V) / 0.05A = 61 Ohms. A 62 Ohm resistor would be suitable. Always check the actual V_F and power rating of the resistor.

Q: What is the difference between \"Radiant Intensity\" (mW/sr) and \"Viewing Angle\"?
A> Radiant Intensity measures the concentration of optical power in a given direction (per steradian). Viewing Angle describes the angular spread of that beam. A device with high radiant intensity but a narrow viewing angle produces a very focused, intense spot. This device has a moderate 60° viewing angle, providing a good balance between beam concentration and coverage.

Q: Why is the storage humidity important?
A: The epoxy packaging can absorb moisture. During the high-temperature soldering process, this trapped moisture can vaporize rapidly, creating internal pressure that can crack the package or delaminate internal bonds—a failure known as \"popcorning.\"

Q: Can I use this for high-speed data transmission like IR remote controls?
A> While it is listed as \"high speed,\" its suitability depends on the required data rate. The 10μs pulse rating for the peak current suggests it can handle moderately fast pulses. For very high-speed communication (e.g., IrDA), components specifically characterized for faster rise/fall times would be more appropriate.