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ISUAL. ROCSAT-2 SSL ISUAL Radiation Effects Environmental Definition and System Evaluation. Innovative Concepts Inc. 8200 Greensboro Drive Suite 801 McLean, VA 22102 (703) 893-2007. Annual Dose Depth. Integral Electron Flux. Differential Proton Flux. Integral Proton Flux.
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ISUAL ROCSAT-2 SSL ISUAL Radiation Effects Environmental Definitionand System Evaluation Innovative Concepts Inc. 8200 Greensboro Drive Suite 801 McLean, VA 22102 (703) 893-2007
Geographic Map of Proton Flux 891 km × 891 km 99° inclination Solar MIN 200 mil Al shielding minimum contour >100 particles/(cm2·s)
Geographic Map of Electron Flux 891 km × 891 km 99° inclination Solar MIN 200 mil Al shielding minimum contour > 10 particles/(cm2 s)
Comments • We don’t believe there are any total dose issues for 200 mil Al shielding. • Very few (and probably low impact) upsets from ADC, op-amps, etc. • Designers should assume that 5 to 10% of SEUs in SDRAM will defeat single bit correct EDAC. • Of proton upsets in SDRAM, <<1% will not be detected by two bit detect EDAC. One set of measurements on ×8 devices, suggest ~0.01%… ~41 undetected upsets per year for 128MB* • Worst Case latch-up prediction for SDRAM is 1 event every ~83 years per device… most devices have no latch-up or latch-up event rates on the order of million years per event per device • SEFI (block type events) SDRAM rate prediction is 1 event every ~6.2 years per device • Worst Case latch-up prediction for ADSP21020 is 1 event every ~9 years per device for Analog Devices. The Lockheed Martin RH-21020 is SEL free. • Relatively high upset rate in the 21020 DSP (~53 per year or 1 every week). *This assumes constant use of the full memory, duty cycle and actual used space will reduce this rate.
Recommendations • SEL in SDRAM • SEL measurements • Current limiting circuitry • Power management ... ON to use and OFF when not in use • Need to consider SEU in 21020 DSP