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.

Electrical parameters are similar to the JEDEC registered 4N49 optocoupler, but with better current transfer ratio (CTR) degradation characteristics due to radiation exposure. Special electrical parametric selections are available upon request.