Infrared Emitter LED 940nm Side View Specification - 3.0x2.8x1.9mm - Forward Voltage 1.2V - Radiant Intensity 3.0mW/sr - English Technical Document

1. Product Overview

This document details the specifications for a discrete infrared emitter component. The device is designed for applications requiring reliable infrared signal transmission, featuring a peak emission wavelength of 940nm. Its primary function is to convert electrical current into infrared radiation, making it a key component in non-visible light communication and sensing systems.

1.1 Core Advantages and Target Market

The component offers a combination of high performance and manufacturability. Key advantages include compatibility with automatic placement equipment and infrared reflow soldering processes, which streamline high-volume assembly. The side-view package with a water-clear dome lens provides a wide viewing angle, suitable for applications where the emission direction is parallel to the mounting PCB. The primary target markets include consumer electronics for remote control functions, short-range wireless data transmission systems, and various security and alarm sensor applications.

2. Technical Parameter Deep Dive

The following sections provide a detailed, objective interpretation of the device's key specifications as defined under standard test conditions (TA=25°C).

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed. Key limits include a power dissipation of 100mW, a peak forward current of 1A under pulsed conditions (300pps, 10µs pulse width), and a continuous DC forward current of 50mA. The device can withstand a reverse voltage of up to 5V, though it is not designed for reverse operation. The operating temperature range is specified from -40°C to +85°C.

2.2 Electrical and Optical Characteristics

These parameters define the device's performance under normal operating conditions. The radiant intensity (I_E) is a minimum of 3.0 mW/sr when driven at a forward current (I_F) of 20mA. The forward voltage (V_F) is typically 1.2V, with a maximum of 1.5V at 20mA. The peak emission wavelength (λ_p) is centered at 940nm, which is in the near-infrared spectrum and invisible to the human eye. The viewing angle (2θ_1/2) is 45 degrees, defined as the full angle where the radiant intensity drops to half of its on-axis value.

3. Binning System Explanation

The device is categorized into different bins based on its radiant intensity output. This allows designers to select components with consistent optical power for their application. The bin codes provided are J, K, and L. For example, a device from Bin J will have a radiant intensity between 3.0 and 4.5 mW/sr when measured at 20mA. Bin K ranges from 4.0 to 6.0 mW/sr, and Bin L has a minimum of 5.0 mW/sr. A test tolerance of ±15% applies to each bin.

4. Performance Curve Analysis

The datasheet includes several typical characteristic curves that illustrate device behavior under varying conditions.

4.1 Spectral Distribution

The spectral distribution curve shows the relative radiant intensity as a function of wavelength. It confirms the peak at 940nm and illustrates the spectral bandwidth, with a typical half-width (Δλ) of 50nm. This information is crucial for matching the emitter with the spectral sensitivity of a corresponding photodetector.

4.2 Forward Current vs. Forward Voltage

This IV curve depicts the relationship between the forward current and the forward voltage drop across the diode. It is non-linear, typical of a semiconductor diode. Understanding this curve is essential for designing the appropriate current-limiting driver circuit to ensure stable operation and prevent thermal runaway.

4.3 Temperature Dependence

Curves showing the variation of forward current and relative radiant intensity with ambient temperature are provided. These graphs demonstrate that the forward voltage has a negative temperature coefficient (decreases with increasing temperature), while the optical output power typically decreases as temperature rises. This is a critical consideration for applications operating in extreme thermal environments.

4.4 Radiation Pattern

A polar radiation diagram visually represents the spatial distribution of the emitted infrared light. The side-view package produces a lambertian-like pattern, with the intensity being highest perpendicular to the chip and tapering off towards the edges, defining the 45-degree viewing angle.

5. Mechanical and Package Information

5.1 Outline Dimensions

The component is an EIA standard surface-mount package. Key dimensions include a body length of approximately 3.0mm, a width of 2.8mm, and a height of 1.9mm. Detailed drawings with tolerances (±0.1mm unless noted) are provided for PCB footprint design.

5.2 Soldering Pad Layout

A recommended land pattern (solder pad design) for the PCB is specified. This includes the pad dimensions and spacing to ensure a reliable solder joint during reflow. The recommendation includes using a metal stencil with a thickness of 0.1mm (4 mils) or 0.12mm (5 mils) for solder paste application.

5.3 Polarity Identification

The cathode is typically marked on the package. The datasheet diagram should be consulted to identify the polarity, which is essential for correct orientation during assembly to ensure the device functions properly.

6. Soldering and Assembly Guidelines

6.1 Reflow Soldering Parameters

The device is compatible with infrared reflow soldering processes, specifically for lead-free (Pb-free) solder. A suggested reflow profile is provided, with key parameters including a pre-heat zone (150-200°C), a peak temperature not exceeding 260°C, and a time above 260°C limited to a maximum of 10 seconds. The profile should adhere to JEDEC standards.

6.2 Storage Conditions

The component is moisture-sensitive, rated at Level 3. If the original moisture-proof bag is unopened, it should be stored at ≤ 30°C and ≤ 90% RH and used within one year. Once opened, components should be stored at ≤ 30°C and ≤ 60% RH. For extended storage outside the original packaging, use a sealed container with desiccant. Components exposed for more than one week should be baked at approximately 60°C for at least 20 hours before soldering to prevent popcorning during reflow.

6.3 Cleaning

If cleaning is necessary after soldering, only alcohol-based solvents like isopropyl alcohol should be used. Harsh or aggressive chemicals may damage the package or lens.

7. Packaging and Ordering Information

7.1 Tape and Reel Specifications

The components are supplied in 8mm wide carrier tape on 13-inch diameter reels. Each reel contains 6000 pieces. Packaging conforms to ANSI/EIA 481-1-A-1994 specifications. The maximum allowable number of consecutive missing components in the tape is two.

8. Application Suggestions

8.1 Typical Application Scenarios

The primary application is as an infrared emitter in remote control units for consumer electronics (TVs, audio systems, air conditioners). It is also suitable for short-distance IR data transmission (e.g., IrDA-like communication), intrusion detection in security alarms, and object sensing where visible light interference must be avoided.

8.2 Design Considerations

Drive Circuit: An LED is a current-driven device. A series current-limiting resistor or a constant current driver circuit is mandatory to set the operating point (e.g., 20mA) and protect the device from overcurrent. The low forward voltage allows it to be driven directly from low-voltage logic circuits (3.3V, 5V) with a simple resistor.

Thermal Management: While the power dissipation is low, ensuring adequate PCB copper area for the cathode pad can help dissipate heat, especially in high ambient temperature conditions or during continuous operation, to maintain output stability and longevity.

Optical Alignment: The side-view form factor is ideal when the IR signal needs to be emitted parallel to the PCB surface. Proper mechanical design of the housing is required to provide an unobstructed path for the IR beam.

9. Technical Comparison and Differentiation

Compared to standard LEDs, this device emits in the infrared spectrum (940nm), making it invisible. Compared to other IR emitters, its key differentiators include the side-view package for specific mounting orientations, a relatively wide 45-degree viewing angle for good coverage, and compliance with RoHS and green product standards. The combination of GaAs material for 940nm emission offers a good balance of efficiency and cost for common remote control applications.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the purpose of the 5V reverse voltage rating if the device is not for reverse operation?

A: This rating indicates the maximum reverse bias the diode junction can withstand without breakdown during occasional or accidental reverse connection in a circuit. It is a robustness specification, not an operating condition.

Q: How do I select the correct bin code?

A: Choose based on the required minimum radiant intensity for your application's link budget (distance, receiver sensitivity). Bin L offers the highest guaranteed output. For cost-sensitive applications where a lower intensity is acceptable, Bin J or K may be suitable.

Q: Can I drive this with a voltage source directly?

A: No. The forward voltage varies with temperature and between individual devices. Driving with a constant voltage, even the typical 1.2V, can lead to excessive current and device failure due to the diode's exponential I-V characteristic. Always use a current-limiting scheme.

11. Practical Design and Usage Case

Case: Designing a Simple IR Remote Control Transmitter.

A common use case is encoding button presses into modulated IR signals. A microcontroller GPIO pin can be used to generate a carrier frequency (e.g., 38kHz) and modulation pattern. This signal drives a transistor switch (e.g., NPN or N-channel MOSFET) in series with the IR emitter. The emitter's anode is connected to the supply voltage (e.g., 3V from two AA batteries) through the transistor, and the cathode is connected to ground. A resistor in series with the emitter sets the pulse current to, for example, 20mA. The side-view package allows the remote to be designed with the PCB parallel to the front face, with a window for the IR beam.

12. Principle of Operation Introduction

An infrared emitter is a semiconductor p-n junction diode fabricated from materials like Gallium Arsenide (GaAs). When a forward bias voltage is applied, electrons from the n-region and holes from the p-region are injected across the junction. When these charge carriers recombine, they release energy. In a light-emitting diode, this energy is released in the form of photons (light). The specific bandgap energy of the semiconductor material (GaAs in this case) determines the wavelength of the emitted photons, which is in the infrared region (940nm) for this device.

13. Industry Trends and Developments

The trend in discrete infrared components continues towards higher efficiency (more radiant output per input watt), which enables longer battery life in portable devices. There is also a drive for miniaturization of packages while maintaining or improving optical performance. Furthermore, components with integrated drivers or logic for simpler system design are becoming more common. The underlying technology for standard 940nm emitters is mature, but process improvements focus on yield, consistency (tighter binning), and cost reduction for high-volume consumer markets.