Photorelays provide higher speed and reliability, a longer life, and require less power and space when compared to mechanical relays. A photorelay is a type of photocoupler that consists of an LED that is optically coupled with a MOSFET. Offered in an ultra-small USOP package, Toshiba photorelays are an ideal choice for applications such as Automatic Test Equipment (ATE) and security systems. This paper discusses advantages and design considerations of photorelays including classification, structure, operation and characteristics.