Radiation-Tolerant Phototransistor Non-Hermetic Surface-Mount Optocoupler

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.


Product LifecycleIn Production
ConditionCTR @ IF = 1 mA
CTR Min.1500
CTR Max.4000
Vcc Max. (V)
Switching Time (μs)25
Isolation @ VDC 1 Sec.1000
Package Photo
Package Info6-Lead Non Hermetic LCC
Radiation TolerantYes
No Base Connection


  • 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

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