IR Emitter and Detector LTE-C9501 Datasheet - 940nm Wavelength - 20mA Forward Current - 1.2V Typical Forward Voltage - English Technical Document

1. Product Overview

The LTE-C9501 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 the needs of modern electronic systems where high performance, compact packaging, and compatibility with automated assembly processes are critical.

1.1 Core Advantages and Target Market

The primary advantages of this component include its compliance with RoHS and green product standards, ensuring environmental friendliness. It is supplied in a 12mm carrier tape on 7-inch diameter reels, making it fully compatible with high-speed automatic placement equipment used in modern PCB assembly lines. The package is also designed to be compatible with infrared reflow soldering processes, which is the industry standard for surface-mount technology (SMT). Its EIA standard package ensures mechanical compatibility with other components and design libraries. The device is targeted at markets such as consumer electronics for remote controls, industrial and commercial systems for IR wireless data transmission, and security systems for alarm and sensing functions.

2. In-Depth Technical Parameter Analysis

The performance of the LTE-C9501 is defined by a set of absolute maximum ratings and detailed electrical/optical characteristics. Understanding these parameters is essential for reliable circuit design.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. They are not intended for normal operation. Key limits include a power dissipation of 100 mW, a peak forward current of 800 mA under pulsed conditions (300 pps, 10 µs pulse), and a continuous DC forward current of 60 mA. The device can withstand a reverse voltage of up to 5V, although it is not designed for reverse operation. The operating temperature range is specified from -40°C to +85°C, with a wider storage temperature range of -55°C to +100°C. The component can endure infrared reflow soldering with a peak temperature of 260°C for a maximum of 10 seconds.

2.2 Electrical and Optical Characteristics

These parameters, measured at a standard ambient temperature of 25°C, define the device's performance under typical operating conditions. The radiant intensity (I_E) ranges from a minimum of 1.0 mW/sr to a maximum of 6.0 mW/sr when driven with a forward current (I_F) of 20mA. The peak emission wavelength (λ_p) is 940 nm, which is in the near-infrared spectrum and invisible to the human eye. The spectral line half-width (Δλ) is typically 50 nm. The forward voltage (V_F) is typically 1.2V, with a range from 1.1V to 1.5V at I_F=20mA. The reverse current (I_R) is a maximum of 10 µA when a reverse voltage (V_R) of 5V is applied. The viewing angle (2θ_1/2) is 20 degrees, defining the angular spread of the emitted infrared radiation where the intensity drops to half of its on-axis value.

3. Binning System Explanation

To ensure consistent performance in production, the LTE-C9501 is sorted into different bins based on its radiant intensity. This allows designers to select components that meet specific output requirements for their application.

3.1 Radiant Intensity Binning

The bin code list categorizes devices into three groups based on their minimum and maximum radiant intensity measured at I_F=20mA. Bin A covers devices with intensity from 1.0 to 2.0 mW/sr. Bin B covers 2.0 to 3.0 mW/sr. Bin C covers 3.0 to 6.0 mW/sr. A tolerance of +/-15% is applied to the intensity within each bin. This binning system helps in applications where consistent signal strength is crucial, such as in data transmission links or proximity sensors.

4. Performance Curve Analysis

Graphical data provides deeper insight into how the device behaves under varying conditions, which is vital for robust system design.

4.1 Spectral Distribution

The spectral distribution curve (Fig.1) shows the relative radiant intensity as a function of wavelength. It confirms the peak at 940 nm and the 50 nm spectral half-width, indicating the bandwidth of the emitted infrared light. This information is important for matching with the spectral sensitivity of corresponding photodetectors and for filtering out ambient light noise.

4.2 Forward Current vs. Ambient Temperature

This curve (Fig.2) illustrates the relationship between the allowable forward current and the ambient temperature. As temperature increases, the maximum permissible forward current decreases due to thermal limitations of the semiconductor junction. This derating curve is critical for ensuring the device operates within its safe operating area (SOA) under all environmental conditions.

4.3 Forward Current vs. Forward Voltage

The IV characteristic curve (Fig.3) shows the non-linear relationship between forward current and forward voltage. It helps in designing the current-limiting circuitry for the LED. The curve's shape is typical for a diode, with a turn-on voltage around 1V.

4.4 Relative Radiant Intensity vs. Ambient Temperature and Forward Current

Figures 4 and 5 show how the optical output power changes with temperature and drive current. Output generally decreases with increasing temperature (Fig.4) and increases with drive current (Fig.5), though not necessarily linearly. These curves are essential for compensating output in temperature-varying environments or for designing constant-brightness circuits.

4.5 Radiation Pattern

The polar radiation diagram (Fig.6) visually represents the viewing angle. The intensity is highest along the central axis (0 degrees) and symmetrically decreases to half its value at +/-10 degrees from the axis, confirming the 20-degree total viewing angle specification. This pattern is important for optical alignment in systems like remote controls or data links.

5. Mechanical and Package Information

5.1 Outline Dimensions

The datasheet provides detailed mechanical drawings of the component. All dimensions are specified in millimeters, with a standard tolerance of ±0.1mm unless otherwise noted. The package is a standard EIA form factor with a water-clear plastic lens for top-view emission.

5.2 Suggested Soldering Pad Layout

A recommended land pattern (solder pad design) for PCB layout is provided. Following these dimensions ensures proper solder joint formation during reflow, good mechanical strength, and correct alignment of the component.

5.3 Tape and Reel Package Dimensions

Detailed drawings show the dimensions of the carrier tape and the 7-inch reel used for automated handling. The tape pockets are designed to hold the component securely, and a top cover tape seals them. Each reel contains 2000 pieces. The packaging conforms to ANSI/EIA 481-1-A-1994 specifications, ensuring compatibility with standard pick-and-place equipment.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Parameters

A suggested infrared reflow profile for lead-free (Pb-free) processes is included. Key parameters include a pre-heat zone of 150-200°C, a pre-heat time of up to 120 seconds maximum, a peak temperature not exceeding 260°C, and a time above this peak of 10 seconds maximum. The profile is based on JEDEC standards to ensure reliable soldering without damaging the component. It is emphasized that the optimal profile may vary based on the specific PCB design, solder paste, and oven used.

6.2 Storage Conditions

For unopened, moisture-proof packaging with desiccant, the components should be stored at 30°C or less and 90% relative humidity or less, with a recommended use-within period of one year. Once the original packaging is opened, the storage environment should not exceed 30°C or 60% relative humidity. Components removed from their original packaging should ideally be reflow-soldered within one week. For longer storage outside the original bag, they should be kept in a sealed container with desiccant or in a nitrogen desiccator. Components stored for more than one week outside the original packaging should be baked at approximately 60°C for at least 20 hours before assembly to remove absorbed moisture and prevent "popcorning" during reflow.

6.3 Cleaning

If cleaning is necessary after soldering, alcohol-based solvents such as isopropyl alcohol are recommended.

6.4 Hand Soldering

If hand soldering with an iron is required, the soldering iron tip temperature should not exceed 300°C, and the contact time should be limited to a maximum of 3 seconds per solder joint.

7. Application Recommendations

7.1 Typical Application Scenarios

The LTE-C9501 is suitable for use as an infrared emitter in remote control units for consumer electronics (TVs, audio systems). It is also applicable in short-range IR wireless data transmission systems, such as in some legacy data links or simple sensor telemetry. Furthermore, it can be used in security alarm systems as part of an infrared beam break sensor or in proximity sensing applications.

7.2 Design Considerations

Current Driving: Always use a series current-limiting resistor or a constant current driver to set the forward current (I_F). Do not exceed the absolute maximum ratings for DC or pulsed current. Refer to the derating curve for high-temperature operation.
Optical Design: Consider the 20-degree viewing angle when designing lenses or reflectors to collimate or focus the IR beam. For reception, ensure the paired photodetector (photodiode or phototransistor) has appropriate spectral sensitivity around 940 nm.
Electrical Design: Although the device can tolerate a 5V reverse voltage, it is not designed for operation in reverse bias. Ensure circuit designs prevent the application of significant reverse voltage during normal operation or transients.
Thermal Management: Ensure the PCB layout provides adequate thermal relief, especially if operating near the maximum current ratings, to prevent overheating and premature degradation.

7.3 Cautions and Reliability

The component is intended for standard electronic equipment. For applications requiring exceptional reliability where failure could jeopardize life or health (e.g., aviation, medical devices, safety systems), specific consultation and qualification are necessary. Always adhere to the specified storage, handling, and soldering conditions to maintain component reliability and performance.

8. Technical Comparison and Differentiation

While the datasheet focuses on a single part, the LTE-C9501's key differentiators within its category include its specific 940nm wavelength, which offers a good balance between output power and compatibility with silicon photodetectors while being less visible than 850nm sources. The water-clear lens (as opposed to tinted) maximizes light output. Its packaging and compatibility with automated SMT processes make it suitable for high-volume manufacturing. The availability of radiant intensity bins allows for design flexibility and cost optimization based on required signal strength.

9. Frequently Asked Questions (FAQ)

Q: What is the purpose of the 940nm wavelength?
A: 940nm infrared light is invisible to the human eye, making it ideal for discreet operation in remote controls and security systems. It is also efficiently detected by common silicon photodiodes and phototransistors.

Q: Can I drive this LED directly from a 3.3V or 5V microcontroller pin?
A: No. You must use a current-limiting resistor in series. Calculate the resistor value using Ohm's Law: R = (V_supply - V_F) / I_F. For example, with a 3.3V supply, V_F=1.2V, and I_F=20mA: R = (3.3 - 1.2) / 0.02 = 105 Ohms. Use the next standard value, like 100 Ohms.

Q: What is the difference between radiant intensity (mW/sr) and luminous intensity?
A: Radiant intensity measures optical power (in watts) per solid angle, relevant for all wavelengths. Luminous intensity is weighted by the sensitivity of the human eye and is used for visible light. Since this is an IR device, radiant intensity is the correct metric.

Q: Why is storage moisture sensitivity important?
A: Plastic-encapsulated SMD components can absorb moisture from the air. During the high heat of reflow soldering, this trapped moisture can vaporize rapidly, causing internal delamination or cracking ("popcorning"), which can destroy the device. Proper storage and baking prevent this.

10. Practical Design and Usage Examples

Example 1: Simple IR Transmitter for Remote Control: Pair the LTE-C9501 with a 38kHz modulation IC (or a microcontroller generating a 38kHz PWM signal) and a transistor switch. The current-limiting resistor sets I_F to 20-40mA for good range. The 20-degree beam provides a reasonable coverage area for pointing a remote at a device.

Example 2: IR Proximity Sensor: Place an LTE-C9501 emitter and a matching phototransistor side-by-side, facing the same direction. An object passing in front will reflect IR light back to the detector. Use pulsed operation of the emitter and synchronous detection in the receiver circuit to reject ambient light. The binning system allows selection of an emitter with sufficient output for the required sensing distance.

Example 3: Data Link: For simple serial data transmission over short distances, drive the LED with the data signal through a current-boosting circuit. The high-speed capability of the underlying semiconductor material (implied by the product line description) supports modulation for data. A matching photodiode with a transimpedance amplifier would be used on the receiver end.

11. Operating Principle Introduction

The LTE-C9501, as an infrared emitter, is a light-emitting diode (LED). Its core is a semiconductor chip, typically made from Gallium Arsenide (GaAs) for 940nm emission. When a forward voltage is applied across the P-N junction, electrons and holes recombine, releasing energy in the form of photons (light). The specific material composition (bandgap) of the semiconductor determines the wavelength of the emitted light, which in this case is 940nm, in the infrared region. The water-clear epoxy package encapsulates the chip, provides mechanical protection, and incorporates a lens that shapes the emitted light into the specified 20-degree viewing angle pattern.

12. Technology Trends and Context

Discrete infrared components like the LTE-C9501 remain fundamental building blocks in electronics. Key trends influencing this field include the continued demand for miniaturization and higher integration, leading to combo packages that might include both emitter and detector in a single housing. There is also a drive towards higher efficiency (more optical output per electrical input) and higher speed for faster data transmission. The adoption of lead-free (Pb-free) and RoHS-compliant manufacturing processes, as seen in this component, is now a universal standard. Furthermore, compatibility with automated pick-and-place and reflow soldering is essential for cost-effective mass production. While application-specific integrated circuits (ASICs) and modules are becoming more common, discrete components offer design flexibility, cost advantages at scale, and are often the preferred solution for custom or optimized optical designs.