DESCRIPTION
OPTOLOGIC™ is the first family of truly logic compatible optically coupled logic interface gates. The family consists of four device types offering LSTTL to TTL and LSTTL to CMOS interfacing. Each of these interfacing functions is available as a buffer (A=B), or as an inverter (A=B). The LSTTL input compatibility is provided by an input integrated circuit, with industry standard logic levels. This input amplifier IC switches a temperature compensated current source driving a high speed 850 nm AlGaAs LED emitter. This novel integration scheme eliminates CTR degradation over time and temperature. The emitter is optically coupled to an integrated photodetector/high-gain, high-speed output amplifier IC. The superior 15kV/µS common-mode noise rejection is ensured through the use of an optically transparent noise shield. The TTL compatible output has a totem-pole with a fan-out of 10. The CMOS compatible output has an open collector Schottkyclamped transistor that interfaces to any CMOS logic between 4.5 and 15 volts.
Fairchild Semiconductor
