The LH1540AAB is a SMD Solid State Relay constructed using a GaAIAs LED for actuation control and an integrated monolithic die for the switch output. This robust relay is ideal for telecom and ground fault applications. It is SPST normally-open switch (form A) that replaces electromechanical relay in many applications. The die is fabricated in a high-voltage dielectrically isolated technology, is comprised of a photodiode array, switch control circuitry and MOSFET switches. In addition it employs current-limiting circuitry which meets lightning surge testing as per ANSI/TIA-968-B and other regulatory voltage surge requirements when overvoltage protection is provided.