LTE-S9511TS-R IR Emitter Datasheet - 940nm Wavelength - 18° Viewing Angle - 1.6V Forward Voltage - English Technical Document

1. Product Overview

The LTE-S9511TS-R is a discrete infrared emitter designed for applications requiring reliable and efficient infrared light sources. It utilizes Gallium Arsenide (GaAs) technology to emit light at a peak wavelength of 940nm, which is ideal for minimizing visible light interference. The device features a side-viewing package with a water-clear lens, providing a focused 18-degree half-intensity viewing angle. This makes it suitable for applications where directed infrared signaling is required. The product is compliant with RoHS and green product standards, is packaged for automated assembly processes, and is compatible with infrared reflow soldering.

1.1 Core Features and Target Market

The primary features of this IR emitter include its high radiant intensity, compact EIA standard package, and suitability for automated PCB assembly. Its core advantages are its specific 940nm wavelength, which is commonly used in consumer electronics remote controls due to its low visibility and good silicon photodetector response, and its side-view configuration which allows for horizontal emission on a PCB. The target markets are primarily consumer electronics, industrial automation, and security systems. Key applications are as an infrared emitter in remote control units and as a PCB-mounted sensor component in various detection and data transmission systems.

2. 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 140 mW at an ambient temperature (TA) of 25°C. It can handle a peak forward current of 1 Ampere under pulsed conditions (300 pulses per second, 10μs pulse width), while the maximum continuous DC forward current is 70 mA. The device can withstand a reverse voltage of up to 5 Volts. The operating temperature range is from -40°C to +85°C, and the storage temperature range is from -55°C to +100°C. The maximum infrared reflow soldering temperature is 260°C for 10 seconds.

2.2 Electrical and Optical Characteristics

These are the typical performance parameters measured at TA=25°C. The radiant intensity (I_E) is 24 mW/sr (typical) at a forward current (I_F) of 20mA, with a test tolerance of ±15%. The peak emission wavelength (λ_Peak) is 940nm. The spectral bandwidth (Δλ), representing the spread of emitted wavelengths, is 50nm. The forward voltage (V_F) is 1.3V typical, with a maximum of 1.6V at I_F=20mA. The reverse current (I_R) is a maximum of 10 μA at a reverse voltage (V_R) of 5V. The viewing angle (2θ_1/2), where intensity drops to half its on-axis value, is 18 degrees.

3. Performance Curve Analysis

The datasheet provides several characteristic curves that are crucial for design engineers. The Spectral Distribution curve (Fig.1) shows the relative radiant intensity across wavelengths, centered at 940nm. The Forward Current vs. Ambient Temperature curve (Fig.2) illustrates how the maximum allowable forward current decreases as ambient temperature increases, which is critical for thermal management. The Forward Current vs. Forward Voltage curve (Fig.3) shows the diode's IV characteristic. The Relative Radiant Intensity vs. Ambient Temperature curve (Fig.4) demonstrates how optical output decreases with rising temperature. The Relative Radiant Intensity vs. Forward Current curve (Fig.5) shows the non-linear relationship between drive current and light output. Finally, the Radiation Diagram (Fig.6) is a polar plot visually representing the 18-degree viewing angle.

4. Mechanical and Packaging Information

4.1 Outline and Package Dimensions

The device conforms to an EIA standard package. The outline drawing provides critical dimensions for PCB footprint design and mechanical integration. All dimensions are provided in millimeters with a general tolerance of ±0.15mm unless otherwise specified. The side-view orientation is clearly indicated.

4.2 Soldering Pad Layout

A recommended soldering pad layout is provided to ensure reliable solder joint formation during reflow or wave soldering. The dimensions are optimized for the package and help prevent tombstoning or poor wetting. A metal stencil thickness of 0.12mm (5 mils) is recommended for solder paste application.

4.3 Tape and Reel Packaging

The component is supplied in 8mm carrier tape on 7-inch diameter reels, compatible with standard automated pick-and-place equipment. Each reel contains 1500 pieces. The packaging specifications, including pocket dimensions, tape width, and reel hub size, follow ANSI/EIA 481-1-A-1994 standards. The tape is sealed with a cover tape to protect components from moisture and contamination.

5. Assembly and Handling Guidelines

5.1 Soldering Process

The device is compatible with infrared reflow soldering processes, particularly for lead-free (Pb-free) solder alloys. A detailed reflow profile suggestion is provided, emphasizing a peak temperature not exceeding 260°C for a maximum of 10 seconds. The profile includes pre-heat stages to minimize thermal shock. For manual soldering, a soldering iron temperature below 300°C for a maximum of 3 seconds per lead is recommended. The guidelines stress that the final profile should be characterized for the specific PCB design, components, and solder paste used.

5.2 Storage and Moisture Sensitivity

The component has a Moisture Sensitivity Level (MSL) of 3. When the original moisture-proof bag with desiccant is unopened, it should be stored at ≤30°C and ≤90% RH and used within one year. Once the bag is opened, components should be stored at ≤30°C and ≤60% RH. If exposed to ambient conditions for more than one week (168 hours), a bake-out at 60°C for at least 20 hours is required before soldering to prevent popcorn cracking during reflow.

5.3 Cleaning and Drive Method

If cleaning is necessary after soldering, only alcohol-based solvents like isopropyl alcohol should be used. The document emphasizes that LEDs are current-operated devices. To ensure uniform brightness when driving multiple LEDs in parallel, an individual current-limiting resistor should be placed in series with each LED. This compensates for minor variations in the forward voltage (V_F) between individual devices.

6. Application Notes and Design Considerations

6.1 Typical Application Scenarios

The primary application is as an infrared emitter in consumer remote controls for televisions, audio systems, and set-top boxes. Its 940nm wavelength is nearly invisible to the human eye, reducing perceived light pollution. It is also suitable for short-range infrared data transmission links, security system sensors (e.g., beam break detectors), and industrial automation where contactless signaling is needed. The side-view package is advantageous when the IR beam needs to be emitted parallel to the PCB surface, such as in edge-sensing applications or within slim devices.

6.2 Design Considerations

Designers must consider the following: Thermal Management: The derating of maximum forward current with increasing ambient temperature (Fig.2) must be respected to ensure longevity. Current Drive: A constant current source or a voltage source with a series resistor is mandatory. Driving with a simple voltage source will lead to thermal runaway and failure. Optical Alignment: The narrow 18° viewing angle requires precise alignment with the receiving photodetector or the intended transmission path. PCB Layout: Follow the recommended solder pad dimensions to ensure proper mechanical stability and solder joint reliability.

6.3 Comparison and Selection

Compared to standard 5mm or 3mm round IR LEDs, this side-view SMT package saves vertical space. Compared to wider-angle emitters, its narrow beam provides higher intensity on-axis, which is beneficial for longer range or lower power consumption. The 940nm wavelength, versus the more common 850nm, offers less visible red glow, which is desirable in consumer applications. Designers should select this component when the design requires a surface-mount, side-emitting IR source with a focused beam for remote control or proximity sensing.

7. Frequently Asked Questions (FAQ)

Q: What is the difference between peak wavelength (λ_Peak) and dominant wavelength (λ_d)?
A: The peak wavelength is the wavelength at which the emitted optical power is maximum (940nm for this device). The dominant wavelength is derived from color perception and is less relevant for monochromatic IR devices; it is more critical for visible LEDs.

Q: Can I drive this LED directly from a microcontroller pin?
A: No. A microcontroller pin typically cannot source 20mA safely or consistently. You must use a transistor switch (e.g., NPN or MOSFET) controlled by the microcontroller to handle the LED current, and always include a series current-limiting resistor.

Q: Why is the storage condition so strict after opening the bag?
A> The plastic packaging absorbs moisture. During the high-temperature reflow soldering process, this trapped moisture can vaporize rapidly, causing internal delamination or \"popcorning,\" which cracks the component and destroys it. The bake-out process removes this absorbed moisture.

Q: How do I calculate the series resistor value?
A> Use Ohm's Law: R = (V_supply - V_F) / I_F. For example, with a 5V supply, a typical V_F of 1.3V, and a desired I_F of 20mA: R = (5 - 1.3) / 0.02 = 185 Ohms. Use the next standard value (e.g., 180 or 200 Ohms) and ensure the resistor's power rating is sufficient (P = I² * R).

8. Technical Principles and Trends

8.1 Operating Principle

An Infrared Emitting Diode (IRED) operates on the principle of electroluminescence in a semiconductor p-n junction. When a forward voltage is applied, electrons from the n-region and holes from the p-region are injected into the junction region. When these charge carriers recombine, they release energy in the form of photons. The wavelength of these photons is determined by the bandgap energy of the semiconductor material. Gallium Arsenide (GaAs) has a bandgap that corresponds to infrared radiation, specifically around 940nm in this device. The side-view package incorporates a molded epoxy lens that shapes the emitted light into the specified viewing angle.

8.2 Industry Trends

The trend in discrete IR components is towards higher efficiency (more radiant output per unit of electrical input), smaller package sizes to enable miniaturization of end devices, and increased compatibility with high-speed data transmission protocols for applications like IrDA. There is also a focus on improving reliability and consistency for automotive and industrial markets. The integration of the emitter with a driver circuit or a photodetector into a single module is another common trend, simplifying design for end-users. The move to lead-free and RoHS-compliant materials and processes, as seen in this component, is a universal industry standard.