IR Emitter and Detector LTE-S9511-E Datasheet - 940nm Wavelength - 20mA Forward Current - 1.5V Forward Voltage - 100mW Power Dissipation - English Technical Document

1. Product Overview

The LTE-S9511-E is a discrete infrared component designed for a broad range of applications requiring reliable infrared emission and detection. It is part of a comprehensive product line that caters to needs for high power, high speed, and wide viewing angles in infrared solutions.

1.1 Core Advantages and Target Market

This component is engineered to meet modern manufacturing and environmental standards. It is a RoHS-compliant green product, supplied in 8mm tape on 13-inch diameter reels for compatibility with high-speed automatic placement equipment. Its design supports infrared reflow soldering processes, making it suitable for volume PCB assembly. Primary target applications include remote control systems, IR wireless data transmission modules, security alarms, and various other consumer and industrial electronics where infrared sensing or signaling is required.

2. Technical Parameters: In-Depth Objective Interpretation

The following parameters define the operational limits and performance characteristics of the device under standard conditions (TA=25°C).

2.1 Absolute Maximum Ratings

These ratings specify the limits beyond which permanent damage to the device may occur. They are not for continuous operation.

• Power Dissipation (Pd): 100 mW. This is the maximum amount of power the device can dissipate as heat.
• Peak Forward Current (I_FP): 1 A. This is the maximum allowable pulsed current under specific conditions (300 pps, 10μs pulse width).
• DC Forward Current (I_F): 50 mA. The maximum continuous forward current for reliable operation.
• Reverse Voltage (V_R): 5 V. The device is not designed for reverse bias operation; exceeding this voltage may cause breakdown.
• Operating Temperature Range (T_opr): -40°C to +85°C. The ambient temperature range for normal device function.
• Storage Temperature Range (T_stg): -55°C to +100°C.
• Infrared Soldering Condition: Withstands 260°C for a maximum of 10 seconds, defining the reflow profile tolerance.

2.2 Electrical and Optical Characteristics

These are the typical performance parameters measured under defined test conditions.

• Radiant Intensity (I_E): 4.0 (Min), 6.0 (Typ) mW/sr. Measured at I_F = 20mA. This indicates the optical power output per solid angle.
• Peak Emission Wavelength (λ_Peak): 940 nm (Typ). The wavelength at which the emitted infrared radiation is strongest.
• Spectral Line Half-Width (Δλ): 50 nm (Typ). The bandwidth of the emitted spectrum at half the peak intensity.
• Forward Voltage (V_F): 1.2 (Typ), 1.5 (Max) V. Measured at I_F = 20mA. The voltage drop across the device when conducting.
• Reverse Current (I_R): 10 μA (Max). Measured at V_R = 5V. A small leakage current under reverse bias.
• Viewing Angle (2θ_1/2): 20 (Min), 25 (Typ) degrees. The full angle where radiant intensity falls to half its on-axis value.

3. Binning System Explanation

The device is available in different performance grades, or \"bins,\" based on radiant intensity. This allows designers to select a component that precisely matches their application's sensitivity or output power requirements.

The bin code list specifies the minimum and maximum radiant intensity for each grade at a test current of 20mA:

• Bin K: 4 to 6 mW/sr
• Bin L: 5 to 7.5 mW/sr
• Bin M: 6 to 9 mW/sr
• Bin N: 7 to 10.5 mW/sr

Selection of a higher bin code (e.g., N over K) typically ensures a higher minimum optical output, which can be critical for achieving longer range or better signal-to-noise ratio in a system.

4. Performance Curve Analysis

The datasheet provides several characteristic curves that illustrate device behavior under varying conditions. These are essential for detailed circuit design and understanding performance trade-offs.

4.1 Spectral Distribution

A curve (Fig.1) shows the relative radiant intensity versus wavelength. It confirms the peak emission at 940nm and the approximately 50nm spectral half-width, which is typical for GaAs-based infrared emitters. This wide spectrum is suitable for use with silicon photodetectors, which have broad sensitivity in the near-infrared region.

4.2 Forward Current vs. Forward Voltage (I-V Curve)

This curve (Fig.3) depicts the non-linear relationship between current and voltage. It shows that the forward voltage increases with current, starting around 1.0V and approaching 1.5V at 100mA. This curve is vital for designing the current-limiting circuitry.

4.3 Temperature Characteristics

Multiple curves illustrate the device's dependence on ambient temperature (T_a).
- Forward Current vs. Ambient Temperature (Fig.2): Likely shows how the maximum allowable forward current derates as ambient temperature increases to prevent exceeding the power dissipation limit.
- Relative Radiant Intensity vs. Ambient Temperature (Fig.4): Demonstrates that the optical output power decreases as temperature rises. This negative temperature coefficient is a key consideration for applications operating in varying thermal environments, as it may require temperature compensation in the drive or receiver circuit to maintain consistent performance.

4.4 Relative Radiant Intensity vs. Forward Current

This curve (Fig.5) shows that radiant intensity is generally proportional to forward current, but the relationship may become sub-linear at very high currents due to heating and efficiency droop. It helps determine the optimal operating current for a desired output level.

4.5 Radiation Diagram

The polar diagram (Fig.6) visually represents the viewing angle. The intensity is highest at 0° (on-axis) and decreases symmetrically, falling to half at approximately ±12.5° (for a 25° viewing angle). This pattern is crucial for aligning the emitter with a detector or for designing optics to shape the beam.

5. Mechanical and Package Information

5.1 Outline Dimensions

The device conforms to an EIA standard package. Key dimensions include the body size, lead spacing, and overall height. All dimensions are provided in millimeters with a typical tolerance of ±0.1mm unless otherwise specified. The package features a water-clear plastic lens with a side-view configuration, which directs the emitted light perpendicular to the PCB plane.

5.2 Suggested Soldering Pad Dimensions

A diagram provides recommended PCB land pattern dimensions to ensure proper solder joint formation and mechanical stability during and after the reflow process. Adhering to these guidelines is critical for manufacturing yield and long-term reliability.

5.3 Polarity Identification

The cathode is typically indicated by a flat side, a notch, or a shorter lead on the package. Correct polarity must be observed during assembly, as applying reverse voltage beyond the maximum rating can instantly damage the device.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Parameters

The device is compatible with infrared reflow processes. Recommended conditions include:
- Pre-heat: 150–200°C for a maximum of 120 seconds.
- Peak Temperature: 260°C maximum.
- Time Above Liquidus: 10 seconds maximum (for a maximum of two reflow cycles).
These parameters align with JEDEC standards and common lead-free solder paste specifications. The profile should be characterized for the specific PCB design, components, and oven used.

6.2 Storage Conditions

The device has a Moisture Sensitivity Level (MSL) of 3.
- Sealed Package: Store at ≤30°C and ≤90% RH. Use within one year of the bag seal date.
- Opened Package: For components removed from the moisture-proof bag, the storage ambient should not exceed 30°C/60% RH. It is recommended to complete IR reflow within one week (168 hours). For longer storage outside the original packaging, use a sealed container with desiccant. Components stored for more than one week should be baked at approximately 60°C for at least 20 hours before soldering to remove absorbed moisture and prevent \"popcorning\" during reflow.

6.3 Cleaning

If cleaning is necessary after soldering, use alcohol-based solvents such as isopropyl alcohol. Harsh or aggressive chemicals should be avoided.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The device is supplied in 8mm carrier tape on 13-inch (330mm) diameter reels. Each reel contains approximately 9000 pieces. The packaging conforms to ANSI/EIA 481-1-A-1994 specifications. The tape has a top cover seal, and a maximum of two consecutive empty component pockets is allowed.

8. Application Suggestions

8.1 Typical Application Scenarios

• Remote Controls: For TVs, audio systems, and other consumer electronics.
• IR Data Transmission: Short-range, simplex wireless communication for sensors or control signals.
• Security Systems: As part of intrusion detection beams or proximity sensors.
• Object Detection: PCB-mounted sensors for counting, position sensing, or edge detection.

8.2 Design Considerations and Drive Method

An LED is a current-operated device. To ensure consistent intensity and longevity, it must be driven with a current source or a voltage source with a series current-limiting resistor. The resistor value (R_s) can be calculated using Ohm's Law: R_s = (V_supply - V_F) / I_F. Where V_F is the forward voltage from the datasheet at the desired operating current I_F. When driving multiple LEDs in parallel, it is strongly recommended to use a separate current-limiting resistor for each LED to prevent current hogging due to minor variations in their V_F characteristics.

9. Technical Comparison and Differentiation

The LTE-S9511-E, with its 940nm wavelength, offers a key advantage over visible-light LEDs or other IR wavelengths: it is virtually invisible to the human eye, making it ideal for discreet operation. Compared to 850nm emitters, 940nm typically has lower solar irradiance background noise, which can improve the signal-to-noise ratio in ambient light conditions. The side-view lens package is specifically designed for applications where the IR beam needs to travel parallel to the PCB surface, a common requirement in slot-type sensors or edge-lit panels.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this LED directly from a 3.3V or 5V microcontroller pin?
A: No. You must use a series resistor to limit the current. For example, with a 5V supply and a target I_F of 20mA (V_F ~1.2V), R_s = (5V - 1.2V) / 0.02A = 190Ω. A 200Ω resistor would be a suitable standard value.

Q: What is the difference between \"Radiant Intensity\" and \"Viewing Angle\"?
A: Radiant Intensity (mW/sr) measures how much optical power is concentrated in a given direction (per steradian). Viewing Angle defines how wide that beam is. A device with high radiant intensity but a very narrow viewing angle projects a powerful but tight beam. This device has a moderate 25° viewing angle, offering a good balance between beam concentration and coverage.

Q: Why is the Moisture Sensitivity Level (MSL 3) important?
A: Plastic packages can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can vaporize rapidly, causing internal delamination, cracks, or \"popcorning,\" which destroys the device. Following the prescribed storage, handling, and baking procedures is essential to prevent this failure mode.

11. Practical Design and Usage Case

Case: Designing a Simple IR Object Detection Sensor.
A common design uses the LTE-S9511-E as both emitter and detector (in a reflective sensing mode) or uses a separate phototransistor. The emitter is pulsed at a specific frequency (e.g., 38kHz). The detector circuit includes a filter tuned to this frequency. When an object reflects the IR beam back to the detector, the circuit registers a signal. Key design steps:
1. Drive Circuit: Use a transistor (e.g., NPN or N-channel MOSFET) switched by a microcontroller to pulse the LED at the desired current (e.g., 50mA pulses) and frequency. Include the calculated series resistor.
2. Receiver Circuit: A phototransistor's output is fed into an amplifier and a band-pass filter centered at the modulation frequency (38kHz). This rejects ambient light (DC and low-frequency) and other IR noise.
3. Alignment: Use the radiation diagram to align the emitter and detector. For reflective sensing, they are often placed side-by-side at an angle, with their fields of view intersecting at the desired sensing distance.
4. PCB Layout: Place the components according to the suggested pad layout. Ensure the clear plastic lens is not obstructed by solder mask or other components.

12. Principle Introduction

The LTE-S9511-E, as an infrared emitter, is a semiconductor diode. When forward biased, electrons and holes recombine in the active region (made of materials like GaAs or AlGaAs), releasing energy in the form of photons. The specific material composition determines the wavelength of these photons; in this case, it is centered around 940nm, which is in the near-infrared spectrum. The side-view lens is molded from water-clear epoxy, which efficiently extracts the light from the semiconductor chip and directs it laterally. The device can also function as a detector because the semiconductor PN junction can generate a small photocurrent when exposed to light of sufficient energy (photons with wavelength shorter than the material's cutoff wavelength). However, its primary optimized function is emission.

13. Development Trends

The field of discrete infrared components continues to evolve. Trends include:
- Higher Efficiency: Development of new semiconductor materials and structures (e.g., multi-quantum wells) to extract more optical power per unit of electrical input, reducing heat generation and power consumption.
- Increased Speed: For data transmission applications, components with faster rise/fall times enable higher data rates.
- Integration: Combining the emitter, detector, and control logic (like modulation/demodulation) into a single package or module simplifies design and improves performance.
- Miniaturization: Continued reduction in package size to fit the demands of ever-smaller consumer electronics while maintaining or improving performance specifications.
- Enhanced Reliability: Improved packaging materials and processes to withstand harsher environmental conditions and longer operational lifetimes.