IR Emitter LED LTE-1650 Datasheet - Clear Package - Forward Voltage 1.6V - Power 100mW - English Technical Document

1. Product Overview

The LTE-1650 is a miniature, end-looking infrared (IR) emitter designed for applications requiring high current drive and low forward voltage characteristics. Its primary function is to emit infrared light at a peak wavelength of 940 nanometers. The device is housed in a clear, transparent plastic package, which is a cost-effective solution for various optoelectronic systems. The core advantages of this component include its ability to handle significant pulse currents, its low voltage operation which reduces power consumption in driver circuits, and its wide viewing angle that simplifies optical alignment in end-user applications. It is typically targeted at markets involving remote control systems, proximity sensors, object detection, and industrial automation where reliable IR signaling is required.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

The device is specified for operation within strict limits to ensure reliability and longevity. The maximum continuous power dissipation is 100 mW at an ambient temperature (T_A) of 25°C. It can withstand a peak forward current of 1 Ampere under pulsed conditions (300 pulses per second, 10 microsecond pulse width). The maximum continuous forward current is rated at 60 mA. A reverse voltage of up to 5 Volts can be applied without damaging the junction. The operational temperature range is from -40°C to +85°C, while the storage temperature range extends from -55°C to +100°C, indicating robust environmental tolerance. The leads can be soldered at a temperature of 260°C for a duration of 5 seconds when measured 1.6mm from the package body.

2.2 Electrical and Optical Characteristics

Key performance parameters are measured at T_A=25°C. The output is characterized by both Aperture Radiant Incidence (E_e, in mW/cm²) and Radiant Intensity (I_E, in mW/sr), both tested at a forward current (I_F) of 20mA. These parameters are binned (see Section 3). The peak emission wavelength (λ_P) is typically 940 nm, which is in the near-infrared spectrum, ideal for many sensing and communication applications as it is invisible to the human eye. The spectral line half-width (Δλ) is 50 nm, defining the spectral purity of the emitted light. The forward voltage (V_F) is typically 1.6 Volts at I_F=50mA, with a maximum of 1.8V, confirming its low-voltage operation. The reverse current (I_R) is a maximum of 100 µA at a reverse voltage (V_R) of 5V. The viewing angle (2θ_1/2) is 60 degrees, providing a broad radiation pattern.

3. Binning System Explanation

The LTE-1650 utilizes a performance binning system primarily based on Radiant Intensity and Aperture Radiant Incidence. This system categorizes components into different performance grades (Bins A, B, C, D) to ensure consistency within a production batch. For example, at I_F=20mA, Bin A devices have a radiant intensity ranging from 1.383 to 4.06 mW/sr, while Bin D devices start at 5.11 mW/sr. This allows designers to select components that match the specific sensitivity requirements of their detector or the required signal strength for their application. There is no explicit binning indicated for forward voltage or wavelength in this datasheet; the wavelength is specified as a typical value of 940nm.

4. Performance Curve Analysis

The datasheet provides several graphs illustrating key relationships. Figure 1 shows the Spectral Distribution, plotting relative radiant intensity against wavelength. This curve confirms the peak at 940nm and the 50nm spectral width. Figure 2 depicts the relationship between Forward Current and Ambient Temperature, showing how the maximum allowable continuous current decreases as ambient temperature increases to stay within the power dissipation limits. Figure 3 is the Forward Current vs. Forward Voltage (I-V) curve, demonstrating the diode's characteristic exponential relationship and its low V_F. Figure 4 shows how Relative Radiant Intensity varies with Ambient Temperature, typically showing a decrease in output as temperature rises. Figure 5 illustrates how Relative Radiant Intensity changes with Forward Current, showing the non-linear relationship between drive current and light output. Finally, Figure 6 is the Radiation Diagram, a polar plot that visually represents the 60-degree viewing angle, showing the angular distribution of the emitted infrared light.

5. Mechanical and Package Information

The device uses a miniature plastic end-looking package. 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 by a maximum of 1.5mm. Lead spacing is measured at the point where the leads exit the package body. The package is clear and transparent, which is beneficial for applications where the emitter might be visible or where the exact chip position needs to be identified for optical alignment. The end-looking design means the primary light emission is from the top surface of the package.

6. Soldering and Assembly Guidelines

The primary soldering specification provided is for lead soldering temperature. The leads can withstand a temperature of 260°C for 5 seconds when measured 1.6mm (0.063 inches) from the package body. This is a critical parameter for wave soldering or hand-soldering processes. For reflow soldering, standard infrared (IR) or convection reflow profiles for plastic-packaged components can generally be used, but the maximum package body temperature should not exceed the storage temperature maximum of 100°C for an extended period. It is advisable to avoid mechanical stress on the leads during and after assembly. Proper storage conditions would involve keeping the components in a dry, static-safe environment within the specified storage temperature range (-55°C to +100°C) to prevent moisture absorption or other degradation.

7. Packaging and Ordering Information

The specific packaging format (e.g., tape and reel, bulk) is not detailed in the provided content. The part number is clearly identified as LTE-1650. The datasheet itself is referenced by Spec No.: DS-50-95-0017, Revision B. The binning code (A, B, C, D) would be a critical part of the ordering information to ensure the correct performance grade is supplied. Designers must specify the required bin when ordering to guarantee the radiant intensity characteristics for their application.

8. Application Recommendations

8.1 Typical Application Scenarios

The LTE-1650 is well-suited for a variety of applications. Its high pulsed current capability makes it ideal for infrared remote control transmitters, where short, high-power bursts are used to communicate signals. The wide viewing angle is advantageous in proximity sensing and object detection, where the exact alignment between the emitter and detector may not be perfectly controlled. It can be used in industrial automation for counting, sorting, or position sensing. Other potential uses include data transmission over short distances, security system beam breaks, and touchless switches.

8.2 Design Considerations

When designing with the LTE-1650, several factors must be considered. The driver circuit must limit the continuous current to 60mA or below, respecting the derating curve at higher ambient temperatures. For pulsed operation, ensure the pulse width and duty cycle do not cause the average power dissipation to exceed 100mW. The low forward voltage allows it to be driven directly from low-voltage logic (e.g., 3.3V or 5V systems) with a simple series current-limiting resistor. The choice of bin (A through D) will directly impact the signal strength received by the detector; a higher bin provides more intensity, which can improve signal-to-noise ratio or allow for longer operating distances. The clear package does not filter the light, so external optical filters may be needed if specific wavelength blocking is required. Heat sinking is generally not required for this package under normal operating conditions, but board layout should allow for some heat dissipation through the leads.

9. Technical Comparison and Differentiation

Compared to standard IR emitters, the LTE-1650's key differentiating advantages are its combination of high current capability (1A pulse, 60mA continuous) and low forward voltage (1.6V typical). Many IR emitters sacrifice one for the other. This combination makes it more efficient and easier to drive from common power supplies. The wide 60-degree viewing angle is another significant advantage over narrower-angle emitters, reducing alignment precision requirements in assembly and final product use. The clear transparent package offers no inherent wavelength filtering, which can be an advantage or disadvantage depending on the application; it provides the full spectral output of the chip, whereas tinted packages might absorb some of the desired IR or visible red light that some chips emit.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED directly from a 5V microcontroller pin?
A: Yes, but you must use a current-limiting resistor. Calculate the resistor value using R = (V_supply - V_F) / I_F. For example, with V_supply=5V, V_F=1.6V, and a desired I_F=20mA, R = (5 - 1.6) / 0.02 = 170 Ohms. Use the next standard value, e.g., 180 Ohms.

Q: What is the difference between the Aperture Radiant Incidence (E_e) and Radiant Intensity (I_E)?
A: Radiant Intensity (I_E, mW/sr) measures the optical power emitted per unit solid angle (steradian), describing how focused the beam is. Aperture Radiant Incidence (E_e, mW/cm²) is the power density incident on a surface (like a detector) at a specified distance, which depends on both the intensity and the distance/geometry. I_E is a property of the source; E_e is what a detector sees.

Q: How does temperature affect performance?
A: As shown in the curves, increasing ambient temperature reduces the maximum allowable continuous forward current (Fig. 2) and typically decreases the radiant output for a given current (Fig. 4). The forward voltage also has a negative temperature coefficient (decreases with increasing temperature), which should be considered in constant-current drive designs.

Q: Why is the device binned?
A: Manufacturing variations cause slight differences in light output efficiency between individual LEDs. Binning sorts them into performance groups (A, B, C, D) so designers can choose a consistent performance level for their circuit, ensuring predictable system behavior.

11. Practical Application Case Study

Case: Simple Object Detection Sensor. A common use is in a modulated infrared detection system to avoid ambient light interference. The LTE-1650 is driven by a 38kHz square wave (a common frequency for IR receivers) through a transistor switch, allowing pulsed current up to the 1A rating for strong signal transmission. It is paired with a corresponding 38kHz-tuned IR photodetector. The wide 60-degree viewing angle of the LTE-1650 allows the emitter and detector to be placed side-by-side on a PCB, with their fields of view overlapping in front of the sensor. When an object enters this overlapping zone, it reflects the modulated IR light from the emitter to the detector. The system electronics then detect this reflected signal. The high output of Bin C or D LEDs would be chosen for this reflective sensing mode to ensure enough signal returns to the detector. The low forward voltage allows the entire circuit, including the LED driver, to be powered from a single 3.3V or 5V rail.

12. Operational Principle

The LTE-1650 is a semiconductor light-emitting diode (LED). Its operation is based on electroluminescence in a semiconductor p-n junction. When a forward voltage is applied, electrons from the n-type region and holes from the p-type region are injected into the junction region. When these charge carriers recombine, they release energy. In this specific device, the semiconductor material (typically based on aluminum gallium arsenide, AlGaAs) is engineered so that this energy is released primarily as photons of infrared light with a peak wavelength around 940 nm. The clear epoxy package encapsulates the semiconductor chip, provides mechanical protection, and acts as a lens that shapes the emitted light into the specified 60-degree viewing angle pattern.

13. Technology Trends and Context

Infrared emitters like the LTE-1650 represent a mature and reliable technology. Current trends in this field focus on increasing efficiency (more light output per unit of electrical input power), enabling higher modulation speeds for faster data transmission, and further miniaturization of packages. There is also a trend toward integrating the emitter with a driver circuit or even a detector into a single module to simplify system design. The 940nm wavelength remains highly popular because it offers a good balance between silicon detector sensitivity (which peaks around 900-1000nm) and low absorption in the atmosphere. While newer materials may offer slightly different wavelength options or higher efficiencies, the fundamental principles and application areas for devices like the LTE-1650 remain stable and widely applicable across consumer electronics, industrial controls, and automotive systems.