Features
• Radiation tolerant version of the 4N49U
• High current transfer ratio (CTR) is guaranteed:
– Over –55 °C to +125 °C ambient temperature range
– At LED current of 1mA
• 1000 VDC electrical isolation
• Same processing and construction as the OLC249, but with a higher CTR

Description
The OLC449 can be used for large satellite constellation applications that require optical isolation in radiation environments such as gamma, neutron, and proton radiation with a high CTR and low saturation VCE. Each optocoupler consists of an LED and N-P-N silicon phototransistor that is electrically isolated, but optically coupled inside a non-hermetic six-pin Leadless Chip Carrier (LCC) package.
Electrical parameters are similar to the JEDEC registered 4N49 optocoupler, but with a higher CTR and better CTR degradation characteristics due to radiation exposure.
The hermetic surface mount variant of the OLC449 optocoupler is available as the OLS449, both in a non-screened catalog version as well as a high-reliability screened version.
The OLC449 is designed for a low LED operating current while providing excellent radiation tolerance margins.
A functional block diagram of the OLC449 is shown in Figure 1. The absolute maximum ratings of the OLC449 are provided in Table 1. Electrical specifications are provided in Table 2.
Typical performance characteristics of the OLC449 are illustrated in Figures 2 through 4. A typical switching test circuit is shown in Figure 5 and package dimensions for the OLC449 are provided in Figure 6.