The OLS249 consists of an LED that is optically coupled to an N-P-N silicon phototransistor, which is mounted and coupled in a custom hermetic surface mount technology (SMT) leadless chip carrier (LCC) package.
The low input current makes the OLS249 well-suited for direct Complementary Metal Oxide Semiconductor (CMOS) to Low Power Schottky Transistor-Transistor Logic (LSTTL) / TTL interfaces.