The NTE3094 consists of a pair of inverting optically coupled gates each with a GaAsP emitting diode and a unique integrated detector. The photons are collected in the detector by a photodiode and then amplified by a high gain linear amplifier that drives a Schottky clamped open collector output transistor. each circuit is temperature, current and voltage compensated. This unique isolator design provides maximum DC and AC circuit isolation between input and output while achieving LSTTL/TTL circuit compatibility. The isolator operational parameters are guaranteed from 0° to +70°C, such that a minimum input current of 5mA will sink an eight gate fan–out (13mA) at the output with 5 volt VCC applied to the detector. This isolation and coupling is achieved with a typical propagation delay of 57ns.
 
Full spec sheet:
https://www.nteinc.com/specs/3000to3099/pdf/nte3094.pdf