IR Emitter LTE-3220L-032A Datasheet - 850nm Wavelength - 30deg Viewing Angle - 150mW Power - English Technical Document

1. Product Overview

The LTE-3220L-032A is a discrete infrared emitter component designed for a variety of optoelectronic applications. It is part of a broad product line that includes components for remote control systems, infrared wireless data transmission, security alarms, and similar uses. The device is constructed using semiconductor technology to emit light in the infrared spectrum.

1.1 Core Advantages and Target Market

The primary advantages of this component include its compliance with environmental regulations, high operational speed, and a narrow radiation angle which allows for directed infrared signaling. It is suitable for pulse operation, making it ideal for digital communication protocols. The target market encompasses consumer electronics manufacturers, industrial automation, security system integrators, and developers of wireless data links where reliable, non-visible light transmission is required.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. The maximum power dissipation is 150 mW. It can handle a peak forward current of 1 A under pulsed conditions (300 pulses per second, 10μs pulse width), while the maximum continuous forward current is 100 mA. The device can withstand a reverse voltage of up to 5 V. The operational temperature range is from -40°C to +85°C, and it can be stored in environments ranging from -55°C to +100°C. The leads can be soldered at 260°C for a duration of 5 seconds, provided the soldering point is at least 4.0mm away from the component body.

2.2 Electrical and Optical Characteristics

These parameters are specified at an ambient temperature (TA) of 25°C. The key performance metrics are:

• Radiant Intensity (Ie): This measures the optical power emitted per unit solid angle. It is typically 24 mW/sr at a forward current (IF) of 20mA and 60 mW/sr at IF=50mA.
• Peak Emission Wavelength (λPeak): The wavelength at which the device emits the most optical power, typically 850 nanometers (nm).
• Spectral Line Half-Width (Δλ): The bandwidth of the emitted light, typically 50 nm, indicating the spread of wavelengths around the peak.
• Forward Voltage (Vf): The voltage drop across the device when conducting, typically 2.0 volts at IF=50mA.
• Reverse Current (IR): The small leakage current when a reverse voltage is applied, maximum 100 μA at VR=5V.
• Viewing Angle (2θ1/2): The angular spread where the radiant intensity is at least half of its maximum value. This device has a relatively narrow viewing angle of 30 degrees.

3. Performance Curve Analysis

The datasheet provides several graphs illustrating device behavior under various conditions.

3.1 Spectral Distribution

Figure 1 shows the relative radiant intensity as a function of wavelength. The curve is centered around 850 nm with a characteristic shape defined by the semiconductor material's bandgap and other physical properties. The half-width is visible as the width of the curve at half its maximum height.

3.2 Forward Current vs. Ambient Temperature

Figure 2 depicts how the maximum allowable forward current decreases as the ambient temperature increases. This derating curve is critical for thermal management in the application design to prevent exceeding the maximum junction temperature.

3.3 Forward Current vs. Forward Voltage

Figure 3 is the current-voltage (I-V) characteristic curve. It shows the exponential relationship typical of a semiconductor diode. The curve helps in designing the driving circuitry, especially for determining the required voltage for a desired operating current.

3.4 Relative Radiant Intensity vs. Ambient Temperature and Forward Current

Figures 4 and 5 show how the optical output power changes with temperature and drive current. Figure 4 indicates that output power generally decreases as temperature rises. Figure 5 shows that output power increases with drive current, but not necessarily in a perfectly linear fashion, especially at higher currents where efficiency may drop.

3.5 Radiation Pattern

Figure 6 is a polar diagram illustrating the spatial distribution of the emitted infrared light. The narrow 30-degree viewing angle is clearly shown, with intensity dropping off sharply outside this cone. This pattern is important for aligning the emitter with a detector in a system.

4. Mechanical and Packaging Information

4.1 Outline Dimensions

The component has a standard package form factor. Key dimensional notes include: all dimensions are in millimeters, with a general tolerance of ±0.25mm unless specified otherwise. The resin under the flange may protrude up to 1.5mm maximum. Lead spacing is measured at the point where the leads exit the package body.

4.2 Polarity Identification

While not explicitly detailed in the provided text, infrared emitters are diodes and therefore have polarity (anode and cathode). The longer lead is typically the anode. The datasheet's dimensional drawing would normally indicate this, and correct polarity must be observed during circuit assembly.

5. Packaging for Automated Assembly

The device is supplied on embossed carrier tape for use with automated pick-and-place machines. Section 6 provides detailed tape and reel specifications, including:

• Tape width (W3): 17.5 to 19.0 mm
• Component pocket pitch (P): 12.5 to 12.9 mm
• Component cavity depth/height (H): 10.5 to 11.5 mm from the tape's base paper
• Lead pitch within the pocket (F): 2.3 to 3.0 mm

6. Soldering and Assembly Guidelines

The key guideline provided is the lead soldering temperature: 260°C for a maximum of 5 seconds, with the stipulation that the soldering point must be at least 4.0mm away from the plastic body of the component. This is to prevent thermal damage to the epoxy package. For reflow soldering, a standard infrared or convection reflow profile with a peak temperature not exceeding 260°C is applicable. Components should be stored in a dry, ambient environment as per the storage temperature range.

7. Application Suggestions

7.1 Typical Application Scenarios

The LTE-3220L-032A is well-suited for:

• Infrared Remote Controls: For TVs, audio systems, and other consumer appliances.
• Short-Range Data Links: For wireless communication between devices like smartphones, computers, or industrial sensors where cables are impractical.
• Proximity and Object Detection: In security systems, automatic doors, or industrial counting systems, often paired with a photodetector.
• Optical Switches and Encoders: Where breaking or reflecting an IR beam indicates position or movement.

7.2 Design Considerations

• Drive Circuit: A current-limiting resistor is essential when driving from a voltage source to set the desired forward current (IF). The circuit must respect the absolute maximum ratings for continuous and pulsed current.
• Thermal Management: Ensure adequate heat sinking or PCB copper area if operating near maximum ratings or in elevated ambient temperatures, using the derating curve as a guide.
• Optical Alignment: The narrow 30-degree viewing angle requires precise mechanical alignment between the emitter and the receiving detector for optimal signal strength.
• Ambient Light Immunity: In environments with strong ambient IR light (e.g., sunlight), modulation of the emitted signal (pulsing) and corresponding demodulation at the receiver are necessary for reliable operation.

8. Technical Comparison and Differentiation

Compared to broader-angle IR emitters, the LTE-3220L-032A's 30-degree viewing angle provides higher intensity within a more focused beam. This results in longer possible transmission distances or lower required drive current for a given range, improving power efficiency. Its 850nm wavelength is a common standard, offering good compatibility with silicon photodetectors which have high sensitivity in this region. The availability for pulse operation makes it versatile for digital communication protocols.

9. Frequently Asked Questions Based on Technical Parameters

Q: What is the difference between radiant intensity (mW/sr) and total output power (mW)?

A: Radiant intensity is power per solid angle, describing how concentrated the beam is. Total power would require integrating intensity over the entire emission pattern. For a narrow-angle device, high radiant intensity can be achieved even with moderate total power.

Q: Can I drive this LED with a 5V supply directly?

A: No. The typical forward voltage is 2.0V at 50mA. Connecting it directly to 5V would cause excessive current and destroy the device. You must use a series resistor (or a constant current driver) to limit the current to the desired value (e.g., 20mA or 50mA).

Q: Why is the peak wavelength 850nm if it's an infrared device?

A> 850nm is in the near-infrared spectrum, just beyond visible red light. It is a popular choice because silicon photodetectors are very sensitive at this wavelength, and it is less susceptible to interference from visible light than longer IR wavelengths.

Q: How do I interpret the \"300pps, 10μs pulse\" rating for peak current?

A: This means the device can handle short, high-current pulses. The 1A peak current is allowed only if the pulse width is 10 microseconds or less and the pulse repetition rate is 300 pulses per second or lower. This allows for high-brightness bursts in communication systems.

10. Practical Use Case Example

Designing a Simple Proximity Sensor: The LTE-3220L-032A can be used as the transmitter in a reflective object sensor. It is paired with a phototransistor placed adjacent to it. The emitter is driven with a pulsed current (e.g., 50mA pulses). When an object comes near, it reflects some of the infrared light back to the phototransistor. The circuit connected to the phototransistor detects this increase in current. The pulsed operation helps distinguish the signal from ambient light. The narrow viewing angle of the emitter helps define a more precise sensing field.

11. Operating Principle Introduction

The device operates on the principle of electroluminescence in a semiconductor p-n junction. When a forward voltage is applied, electrons and holes are injected into the junction region where they recombine. In this specific material system, the energy released during recombination is emitted as photons with a wavelength corresponding to the energy bandgap of the semiconductor, which is engineered to be approximately 850nm (infrared). The clear transparent epoxy package allows this light to escape efficiently.

12. Industry Trends and Developments

The trend in infrared components continues towards higher efficiency (more light output per electrical watt input), higher speed for faster data transmission, and smaller package sizes for integration into compact devices. There is also ongoing development in specific wavelength ranges for applications like gas sensing or optical communications. The move to lead-free and RoHS-compliant manufacturing, as seen with this component, is a standard industry requirement driven by environmental regulations. Integration of emitters with drivers or detectors in multi-chip modules is another area of advancement.