Radiation Tolerant Phototransistor Hermetic Surface Mount Optocoupler

The OLS449 is specifically designed for high reliability and space applications that require optical isolation in radiation environments such as gamma, neutron, and proton radiation with a high current transfer ratio (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 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 OLS449 is designed for a low LED operating current while providing excellent radiation tolerance margins. The OLS449 has 100 percent high-reliability screenings available.


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 Hermetic Ceramic LCC
Radiation TolerantYes
No Base Connection


  • Radiation tolerant version of the 4N49U
  • High current transfer ratio (CTR) is guaranteed:
    • Over –55 °C to +100 °C ambient temperature range
    • At LED current of 1mA
  • 1000 VDC electrical isolation
  • Same reliable processing and construction as the OLS249, but the a higher CTR
  • High-reliability screenings are available

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