The OLF300 is suitable for interfacing Transistor-Transistor Logic (TTL) to Low Power Schottky Transistor-Transistor Logic (LSTTL), TTL, or Complementary Metal Oxide Semiconductor (CMOS), as well as wide bandwidth analog applications. Each OLF300 has a light emitting diode and an integrated photodiode transistor detector mounted and coupled in a custom 8-pin hermetic flat pack package providing 1000 Vdc electrical isolation between input and output. The integrated photodiode transistor improves switching speed by orders of magnitude as compared to standard photo transistors, by reducing the base to collector capacitance. The internal shield provides excellent common-mode immunity performance.