The OLS300 is suitable for interfacing Transistor-Transistor Logic (TTL) to Low Power Schottky Transistor-Transistor Logic (LSTTL), or Complementary Metal Oxide Semiconductor (CMOS), as well as wide bandwidth analog applications. Each OLS300 has an LED and integrated photodiode transistor detector mounted and coupled in a custom hermetic surface mount leadless chip carrier (LCC) ceramic package that provides 1500 VDC of electrical isolation between the input and output. The integrated photodiode transistor improves the switching speed by orders of magnitude as compared to standard phototransistors by reducing the base-to-collector capacitance. The OLS300’s device mounting is achieved with reflow soldering or conductive epoxies.