During SEL characterization, the device was heated using forced hot air, maintaining the IC temperature at 125°C. The temperature was monitored by means of a K-type thermocouple attached as close to the IC as possible. The species used for the SEL testing was a silver (⁴⁷Ag) ion with an angle-of-incidence of 0° for an LET_EFF = 43 MeV-cm²/mg. The kinetic energy in the vacuum for this ion is 1.634 GeV (15-MeV/amu line). A flux of approximately 10⁵ ions/cm²-s and a fluence of approximately 10⁷ ions were used for the runs. The Vs supply voltage is supplied externally onboard at the recommended maximum voltage setting of 40 V. Run duration to achieve this fluence was approximately 2 minutes. No SEL events were observed shown in Table 5-1. Figure 5-1 shows a plot of the current vs time.

No SEL events were observed, indicating that the OPA4H199-SEP is SEL-immune at LET_EFF = 43 MeV-cm²/mg and T = 125°C. Using the MFTF method described in Appendix A and combining (or summing) the fluences of the two runs @ 125°C (2 × 10⁷), the upper-bound cross-section (using a 95% confidence level) is calculated in Equation 1: