Why do I need optical isolation?

Optical isolation improves the reliability of I/O applications in industrial, marine, mobile or similar environments, thus alleviating the problems caused by ground loops, electromagnetic interference (EMI) and surges.

Duplicate ground references, referred to as ‘ground loops’, can occur when there is more than one path to ground between connected devices. Ground loops can also happen when devices are connected to different power sources and there is a difference in the ground potential between the devices. Electronic devices inadvertently create multiple paths to ground through the earth ground in the AC wiring as well as the ground references in the I/O interfaces. Ground loops have a measurable voltage difference that is sometimes substantial and can generate enough current to damage sensitive electronic devices.

Ground loops also behave like antennas and will easily pick up electromagnetic interference (EMI) that can cause communication problems. EMI is generated by other electrical sources, such as motors, transformers, fluorescent lighting and other electrical equipment found in industrial environments.

Additionally, electrical surges can come from the host computer and be radiated to peripheral devices as the surge seeks a path to ground. Surges can also come from connected devices through accidental contact with a high voltage conductor or static discharge.

Optical isolation removes ground loops, provides immunity to electrical interference (EMI), and creates a physical barrier between connected devices. This barrier prevents electrical surges from damaging equipment on the other side.

Sealevel offers a variety of optically isolated products including the following:

• SeaISO® USB Isolators
• USB Serial Adapters
• PCI Express Serial
• PCI Serial
• Compact PCI Serial
• Serial Interface Converters
• Digital I/O Interfaces with Optically Isolated Inputs