The 4N2x and 4N4x Series optically-coupled isolators employ hermetically sealed metal packages–either surface mount 6-pin leadless chip carriers, or through-hole TO-78 metal cans and are processed to TX and TXV MIL-PRF-19500/486 and /548 specs. COTS-level devices are also available. The components consist of a 935-nm (4N2x Series) or an 890-nm (4N4x Series) wavelength infrared-emitting diode and a NPN silicon phototransistor in a sealed metal package with a base contact for conventional transistor biasing. Devices are also available with the collector pin electrically isolated from the case. Packaging options for the 4Nxx Series include a standard TO-78 metal can through-hole package and a surface mount leadless chip carrier. OPTEK TECHNOLOGY INC., Carrollton, TX. (972) 323-2200.