IR Emitter and Detector LTE-3277 Datasheet - High Speed, High Power, Clear Package - English Technical Document

1. Product Overview

The LTE-3277 is a high-performance optoelectronic component designed for applications requiring fast response times and significant radiant output. Its core advantages lie in its combination of high-speed operation and high radiant intensity, making it suitable for pulse-driven systems. The device is housed in a clear, transparent package, which is beneficial for applications where precise optical alignment or minimal package interference with the emitted/detected light is required. The target market includes industrial automation, communication systems (like infrared data transmission), sensing applications, and security systems where reliable infrared signaling or detection is critical.

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. Operating the device continuously at or near these limits is not recommended.

• Power Dissipation (P_D): 120 mW. This is the maximum total power the device can dissipate as heat under any operating condition.
• Peak Forward Current (I_FP): 1 A. This high current rating is applicable only under pulsed conditions (300 pulses per second, 10 µs pulse width). It highlights the device's capability for brief, high-intensity bursts of light.
• Continuous Forward Current (I_F): 100 mA. This is the maximum DC current that can be applied continuously to the device.
• Reverse Voltage (V_R): 5 V. Exceeding this voltage in the reverse direction can cause breakdown.
• Operating & Storage Temperature: -40°C to +85°C. This wide range ensures reliability in harsh environmental conditions.
• Lead Soldering Temperature: 260°C for 6 seconds at 1.6mm from the body. This is critical for PCB assembly processes to prevent thermal damage.

2.2 Electrical & Optical Characteristics

These parameters are specified at an ambient temperature (T_A) of 25°C and define the typical performance of the device.

• Radiant Intensity (I_E): 20 mW/sr (Min), 36 mW/sr (Typ) at I_F = 20mA. This measures the optical power emitted per unit solid angle, indicating its brightness.
• Peak Emission Wavelength (λ_P): 865 nm (Typical). This places the device in the near-infrared spectrum, invisible to the human eye but detectable by silicon photodiodes.
• Spectral Line Half-Width (Δλ): 25 nm (Typical). This indicates the spectral purity or bandwidth of the emitted light.
• Forward Voltage (V_F): 1.45V (Typ), 1.65V (Max) at I_F = 20mA. This is the voltage drop across the device when conducting.
• Forward Voltage Variation (ΔV_F): 0.4V (Max). Defined as V_F@50mA - V_F@20mA, it indicates the dynamic resistance characteristic.
• Reverse Current (I_R): 10 µA (Max) at V_R = 5V. This is the leakage current when the device is reverse-biased.
• Viewing Angle (2θ_1/2): 25° (Min), 30° (Typ). This is the full angle at which the radiant intensity drops to half of its peak value, defining the beam spread.
• Dice Center: 0 to 0.12 mm. This specifies the tolerance for the position of the semiconductor die within the package, important for optical alignment.

3. Performance Curve Analysis

The datasheet provides several graphs illustrating key relationships. These are essential for circuit design and understanding performance under non-standard conditions.

3.1 Spectral Distribution (Fig. 1)

This curve shows the relative radiant intensity as a function of wavelength. It confirms the peak at approximately 865 nm and the 25 nm half-width, providing insight into the spectral characteristics useful for filtering and receiver selection.

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

This derating curve is crucial for thermal management. It shows how the maximum allowable continuous forward current decreases as the ambient temperature increases, ensuring the device stays within its safe operating area (SOA) and power dissipation limits.

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

This is the standard I-V characteristic curve. It demonstrates the exponential relationship between current and voltage, which is fundamental for designing the driving circuitry, whether constant current or pulsed.

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

Figure 4 shows how the optical output power decreases with increasing temperature for a fixed drive current (e.g., 20mA). This temperature coefficient is vital for applications requiring stable output. Figure 5 shows how the output power increases with drive current, highlighting the non-linear relationship and saturation effects at higher currents.

3.5 Radiation Diagram (Fig. 6)

This polar plot visually represents the viewing angle (2θ_1/2 ≈ 30°). The concentric circles represent relative intensity levels (e.g., 1.0, 0.8, 0.6...). This diagram is essential for designing optical systems, lenses, and for understanding the spatial distribution of the emitted light.

4. Mechanical & Packaging Information

4.1 Package Dimensions

The device uses a standard through-hole package. Key dimensional notes from the datasheet include:

• All dimensions are in millimeters (inches provided in parentheses).
• A general tolerance of ±0.25mm(.010") applies unless specified otherwise.
• The maximum protrusion of resin under the flange is 1.5mm(.059").
• Lead spacing is measured at the point where the leads exit the package body.

The clear transparent package material minimizes absorption of the emitted IR light and allows for visual inspection of the internal die.

4.2 Polarity Identification

For a standard LED package, the longer lead typically denotes the anode (positive), and the shorter lead or a flat side on the package rim denotes the cathode (negative). Designers must consult the specific package drawing for unambiguous identification.

5. Soldering & Assembly Guidelines

The absolute maximum rating for lead soldering is explicitly given: 260°C for a maximum of 6 seconds, measured at a distance of 1.6mm (0.063 inches) from the package body. This parameter is critical for wave soldering or hand-soldering processes.

• Reflow Soldering: While not explicitly stated for SMD, the 260°C limit suggests compatibility with many lead-free reflow profiles, provided the peak temperature and time above liquidus are carefully controlled to keep the leads at the package interface within spec.
• Precautions: Avoid mechanical stress on the leads. Use appropriate thermal relief during soldering. Do not exceed the specified temperature and time.
• Storage Conditions: Store in a dry, anti-static environment within the specified temperature range (-40°C to +85°C) to prevent moisture absorption (which can cause "popcorning" during reflow) and electrostatic discharge damage.

6. Application Suggestions

6.1 Typical Application Scenarios

• Infrared Data Transmission: Its high-speed capability makes it suitable for IrDA-compliant data links, remote controls, and short-range wireless communication.
• Industrial Sensing: Used in proximity sensors, object detection, counting systems, and edge detection in automation. The clear package is advantageous.
• Security Systems: Can be used in beam-break detectors for intrusion alarms or as an invisible light source for CCTV illumination paired with IR-sensitive cameras.
• Optical Switches & Encoders: The fast response time is ideal for detecting rapid changes in position or speed.

6.2 Design Considerations

• Drive Circuitry: For pulsed operation (utilizing the 1A peak current), a fast-switching transistor or MOSFET driver circuit is necessary. A current-limiting resistor is mandatory for DC operation to prevent exceeding the 100mA continuous current.
• Thermal Management: Even with 120mW max dissipation, ensure adequate PCB copper area or heatsinking if operating near maximum ratings, especially at high ambient temperatures. Refer to the derating curve (Fig. 2).
• Optical Design: The 30° viewing angle and radiation pattern (Fig. 6) must be considered when pairing with lenses, apertures, or receivers to achieve the desired beam shape and detection sensitivity.
• Receiver Pairing: When used as an emitter, pair it with a photodetector (photodiode or phototransistor) sensitive around 865 nm for optimal system performance.

7. Technical Comparison & Differentiation

Compared to standard infrared LEDs, the LTE-3277 differentiates itself primarily through its high-speed and high-power capabilities in a clear package. Many standard IR LEDs have lower peak current ratings and slower rise/fall times, limiting their use in high-bandwidth pulsed applications. The combination of 1A peak current and suitability for pulse operation indicates optimized semiconductor design and packaging for rapid thermal dissipation during short pulses, enabling brighter, faster signals.

8. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED with a 5V supply directly?
A: No. You must use a series current-limiting resistor. For example, to achieve I_F=20mA with a V_F~1.5V from a 5V supply: R = (5V - 1.5V) / 0.02A = 175Ω. Use the next standard value (e.g., 180Ω) and check power dissipation in the resistor.

Q: What does "available for pulse operating" mean practically?
A: It means the semiconductor junction and package are designed to handle very high instantaneous currents (up to 1A) for very short durations (10µs) without degradation, allowing for much higher peak optical output than its DC rating would suggest. This is key for achieving long range or high signal-to-noise ratio in pulsed systems.

Q: Why is the viewing angle important?
A> It determines the spatial coverage of the emitted light. A narrow angle (like 30°) produces a more focused beam, suitable for longer-distance, directed communication. A wider angle is better for short-range, broad-area illumination or sensing.

9. Practical Use Case Example

Designing a Proximity Sensor: The LTE-3277 can be used as the emitter in a reflective proximity sensor. It would be pulsed at 1A for 10µs at a low duty cycle (e.g., 1%). A matched photodetector placed nearby would detect the IR light reflected from an object. The timing and amplitude of the detected pulse indicate presence and approximate distance. The high peak power ensures a strong return signal, while the clear package doesn't attenuate the emitted or reflected light. The circuit must include a driver for the high-current pulse and a sensitive amplifier for the detector signal.

10. Operating Principle

The LTE-3277, when functioning as an infrared emitter, operates on the principle of electroluminescence in a semiconductor p-n junction. When forward-biased (anode positive relative to cathode), electrons and holes are injected across the junction. Their recombination releases energy in the form of photons. The specific semiconductor materials used (typically aluminum gallium arsenide - AlGaAs) are chosen to produce photons with an energy corresponding to infrared light, peaking at around 865 nm wavelength. The "high speed" refers to the rapid rate at which the junction can be turned on and off, determined by carrier lifetime and circuit capacitance.

11. Technology Trends

In the field of infrared optoelectronics, trends include the development of devices with even higher modulation speeds for data communication (e.g., for Li-Fi or high-speed industrial buses), increased power efficiency (more mW/sr per mA), and the integration of emitters and detectors into multi-element arrays or combined with driving ICs in smart sensor modules. There is also a push towards miniaturization in surface-mount device (SMD) packages while maintaining or improving thermal performance. The clear package trend supports applications requiring precise optical coupling and minimal signal loss.