Solid state relays (SSRs) add isolation to solid state switching. There are two reasons why isolation is important. First is safety, to protect humans from potentially lethal currents. The second is noise, to protect sensitive circuitry from electrical noise, minimize RF emissions, and simplify the design process. Safety and noise isolation requirements are determined by industry and governmental agencies. Vishay’s SSRs help to meet and/or exceed these standards. It is important to note that not every application needs an SSR. For AC-only applications, one can use a phototriac, and Vishay offers an extensive family of phototriacs to choose from. Sometimes phototriacs are referred to as SSRs, but at Vishay, they reserve the term SSR for devices that include MOSFET outputs which can be used for both AC and DC applications.