IL4218

IL4218 Application Field and Working Principle

The IL4218 are digital opto-isolators and integrated circuit (IC) combination consisting of high intensity infrared LEDs and a high gain photo coupled transistor. They are designed for high speed interface operation and provides a degree of electrical isolation between input and output — eliminating the effects of ground loop and making them suitable for use in electronic control systems employing closed loop feedback and high gain circuit design.

General Features

• Compact Package
• Operating Temperature Range: -40°C to +85°C
• Isolation Voltage: 5KVrms
• Current Transfer Ratio: 100%
• Root Mean Square (RMS) Current Transfer Ratio: +40~-20mA

Application Fields

IL4218 opto-isolators are often used in areas such as interfaces between industrial and commercial systems. They are often used as protection components in industrial systems prone to heavy ESD (electrical surge) and electrical isolation between electronic sensors, motors, and controllers. In commercial systems, IL4218 can also be used to protect I/O systems from high voltage flows and transients.

Working Principle

The IL4218 opto-isolator is composed of an LED and a phototransistor. Light from the LED is photo-coupled through the isolation barrier. This enables the LED to act as an input and the phototransistor as an output. The photo coupled current flows through the transistor between the pointed emitter and collector. When the input LED current is low the transistor will be off. When the current reaches the ON threshold, the transistor will be ON and can be used to control the output voltage.

Optoisolators - Triac, SCR Output

The IL4218 is a Triac-based optoisolator with an SCR output, meaning it can be used to control Triac-based loads, such as electric motors and lamp outputs. This type of optoisolator is typically used for low voltage AC control, and provides isolation between the input control signal and the output load. The SCR output can also be used for DC applications, allowing for robust isolation between disparate electrical circuits.

Conclusion

In summary, the IL4218 opto-isolator is a Triac-based optoisolator with an SCR output, used to provide high-speed signal and electrical isolation between input and load circuits. It can be used for both AC and DC control and isolation applications, and is often found in industrial control, instrumentation, and commercial systems.