Infrared Emitter LTE-3677 Datasheet - High Speed, High Power, Clear Package - English Technical Document

1. Product Overview

The LTE-3677 is a high-performance infrared (IR) emitter component designed for applications requiring fast response times and significant radiant output. Its core advantages lie in its combination of high speed and high power, making it suitable for pulse-operated systems. The device is housed in a clear, transparent package, which is typical for IR emitters to allow efficient transmission of the infrared light. The target market includes industrial automation, remote controls, optical switches, data transmission links, and sensor systems where reliable and rapid infrared signaling 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. The maximum continuous forward current is 100 mA, while a much higher peak forward current of 1 A is permissible under pulsed conditions (300 pulses per second, 10 μs pulse width). This highlights the device's capability for brief, high-intensity bursts of light. The power dissipation is rated at 260 mW. The operating temperature range is specified from 0°C to +70°C, and storage can be from -20°C to +85°C. Lead soldering temperature should not exceed 260°C for 5 seconds when measured 1.6mm from the body.

2.2 Electrical and Optical Characteristics

Key parameters are measured at an ambient temperature (T_A) of 25°C. The radiant intensity (I_E) is a primary measure of optical output power per solid angle. For a forward current (I_F) of 20mA, typical values are binned: BIN D offers 9.62 to 19.85 mW/sr, and BIN E offers 13.23 mW/sr. The peak emission wavelength (λ_P) is between 860 nm and 895 nm, centered around 875 nm, placing it firmly in the near-infrared spectrum. The spectral line half-width (Δλ) is 50 nm, indicating the bandwidth of the emitted light. Electrical characteristics include a forward voltage (V_F) of 1.5V typical at 50mA (1.67V at 100mA) and a reverse current (I_R) of 100 μA maximum at 5V reverse bias. The rise and fall time (T_r/T_f) is 40 ns, confirming its high-speed capability. The viewing angle (2θ_1/2) is 30 degrees.

3. Binning System Explanation

The datasheet indicates a binning system primarily for radiant intensity and aperture radiant incidence. Two bins are mentioned: BIN D and BIN E. BIN E appears to represent a tighter or higher-performance subset within the range defined for BIN D. For radiant intensity at I_F=20mA, BIN D covers 9.62-19.85 mW/sr, while BIN E is specified as 13.23 mW/sr. This allows manufacturers to select components with more consistent or guaranteed minimum performance levels for their specific application requirements, ensuring system performance uniformity.

4. Performance Curve Analysis

The datasheet references several typical characteristic curves. Figure 1 shows the Spectral Distribution, illustrating the shape and width of the emitted infrared light centered around 875 nm. Figure 2, Forward Current vs. Ambient Temperature, likely shows the derating of the maximum allowable current as temperature increases. Figure 3, Forward Current vs. Forward Voltage, depicts the diode's IV characteristic. Figure 4, Relative Radiant Intensity vs. Ambient Temperature, shows how the optical output power decreases with increasing temperature, a key consideration for thermal management. Figure 5, Relative Radiant Intensity vs. Forward Current, demonstrates the relationship between drive current and light output, which is typically linear within a range. Figure 6 is the Radiation Diagram, a polar plot showing the angular distribution of the emitted light intensity, corresponding to the 30-degree viewing angle.

5. Mechanical and Package Information

The package is a standard through-hole style with a clear lens. Key dimensional notes include: all dimensions are in millimeters, with a general tolerance of ±0.25mm unless specified otherwise. The maximum protrusion of resin under the flange is 1.5mm. Lead spacing is measured at the point where the leads emerge from the package body. The exact dimensions are provided in a drawing (not fully detailed in the text extract), which would include body diameter, lead length, and lens shape.

6. Soldering and Assembly Guidelines

The primary guideline provided is for lead soldering: the temperature must not exceed 260°C for a duration of 5 seconds when measured at a distance of 1.6mm (0.063 inches) from the package body. This is crucial to prevent thermal damage to the internal semiconductor die and the epoxy package. For wave or reflow soldering (though not explicitly mentioned for surface-mount as this is a through-hole part), standard industry profiles for similar components should be followed, with careful attention to peak temperature and time above liquidus. Proper handling to avoid electrostatic discharge (ESD) is also recommended, though not stated, as semiconductor devices are generally ESD-sensitive.

7. Packaging and Ordering Information

The part number is LTE-3677. The datasheet is identified by Spec No.: DS-50-99-0015, Revision A. The document is paginated (Page 1 of 3, etc.). Specific packaging details such as reel size, tube quantities, or tray packing are not provided in this excerpt. Ordering would typically involve the base part number LTE-3677, and potentially a suffix to denote binning (e.g., LTE-3677-D or LTE-3677-E) if available as separate orderable items.

8. Application Recommendations

8.1 Typical Application Scenarios

The LTE-3677 is ideal for applications requiring fast, pulsed infrared light. This includes: Industrial optical sensors (e.g., object detection, counting, edge detection). Infrared data transmission links for short-range communication. Remote control units for consumer electronics. Optical encoders and position sensing. Smoke detectors and other analytical sensing equipment. Security systems using infrared beams.

8.2 Design Considerations

Drive Circuit: Use a current-limiting resistor or a dedicated LED driver circuit to control the forward current. For pulsed operation, ensure the driver can deliver the required peak current (up to 1A) with fast edges to leverage the 40 ns rise/fall time. Thermal Management: Although power dissipation is 260 mW, operating at high continuous currents or in elevated ambient temperatures requires attention to heat sinking via the leads or board layout to maintain performance and longevity. Optical Design: The 30-degree viewing angle defines the beam spread. Lenses or reflectors may be used to collimate or focus the beam as needed. The clear package is suitable for applications where the emitter is visible, but an IR filter may be used to block visible light if required. Pairing with a Detector: Select a photodetector (photodiode, phototransistor) with a spectral sensitivity that matches the emitter's 875 nm peak wavelength for optimal system efficiency.

9. Technical Comparison

Compared to standard, slower IR LEDs, the LTE-3677's key differentiation is its high speed (40 ns rise/fall time), enabling data transmission at higher rates. Its high power output (high radiant intensity) provides a stronger signal, increasing signal-to-noise ratio and operational range. The availability for pulse operation with a high peak current rating allows it to be driven very brightly in short bursts, which is efficient and can extend perceived range. The clear package is standard for such emitters. When selecting an IR emitter, engineers would compare these parameters—speed, output power, wavelength, viewing angle, and package—against alternatives to find the best fit for bandwidth, range, and physical layout requirements.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED with a continuous current of 150 mA?
A: No. The Absolute Maximum Rating for continuous forward current is 100 mA. Exceeding this rating risks permanent damage to the device.

Q: What is the difference between BIN D and BIN E?
A: BIN E specifies a typical radiant intensity of 13.23 mW/sr at 20mA, which falls within the wider range of BIN D (9.62-19.85 mW/sr). BIN E likely represents a selection of devices with more consistent performance around that typical value, whereas BIN D encompasses the full manufacturing spread.

Q: How does temperature affect performance?
A: As shown in the typical curves, radiant intensity decreases as ambient temperature increases. The forward voltage also typically decreases with rising temperature. The operating current must be derated above 25°C as per the derating curve (Fig. 2) to stay within the power dissipation limit.

Q: Is a series resistor necessary?
A: Yes, for most simple drive circuits. The LED must be driven with a controlled current. Using a voltage source directly would cause excessive current to flow, destroying the device. Calculate the resistor value based on the supply voltage, desired forward current (I_F), and the forward voltage (V_F) from the datasheet.

11. Practical Use Case

Scenario: High-Speed Object Detection Sensor. An assembly line uses a photoelectric sensor to detect small components passing at high speed. The LTE-3677 is used as the infrared light source, pulsed at 10 kHz with 1A peaks. A matched phototransistor is placed opposite. When an object interrupts the beam, the receiver detects the absence of the pulsed signal. The 40 ns response time of the LTE-3677 ensures that the light pulses are sharp and well-defined, allowing the sensor electronics to reliably distinguish between pulses even at high speeds, minimizing false triggers and enabling accurate counting of very fast-moving objects.

12. Principle of Operation

An infrared emitter is a semiconductor diode. When a forward voltage is applied, electrons recombine with holes within the device's active region, releasing energy in the form of photons. The specific materials used in the semiconductor structure determine the wavelength of the emitted light. For the LTE-3677, this results in photons in the near-infrared spectrum around 875 nm, which is invisible to the human eye but can be detected by silicon photodiodes and other IR-sensitive sensors. The clear epoxy package acts as a lens, shaping the output beam to the specified viewing angle.

13. Technology Trends

The field of optoelectronics continues to advance towards higher efficiency, higher speed, and greater integration. Trends relevant to devices like the LTE-3677 include: Increased Power and Efficiency: New semiconductor materials and structures aim to deliver more optical power per unit of electrical input, reducing heat generation. Smaller Form Factors: The drive towards miniaturization pushes for surface-mount device (SMD) packages with similar or better performance than through-hole types. Enhanced Speed: Research continues to push modulation speeds for IR emitters to enable faster data communication, such as in Li-Fi or high-speed optical interconnects. Wavelength Specificity: Development of emitters with narrower spectral linewidths for applications in gas sensing and spectroscopic analysis.