During SEL characterization, the device was heated using forced hot air, maintaining the die temperature at 125°C. The temperature was monitored by means of a K-type thermocouple attached as close as possible to the die. The species used for the SEL testing was a Praseodymium (⁵⁹Pr) ion with angle of incidence at 0° and 25° for an LET_EFF = 76.18 MeV-cm²/mg and 65.65 MeV-cm²/mg. The kinetic energy in the vacuum for this ion is 0.885 GeV (15-MeV/amu line). A flux of approximately 10⁵ ions/cm²-s and a fluence of approximately 10⁷ ions were used for all seven runs. The VCC voltage was set to the recommended maximum at 3.6 V. Run duration to achieve this fluence was approximately two minutes. No SEL events were observed during all four runs shown in Table 5-1. Figure 5-1 shows a plot of the current versus time.

No SEL events were observed, indicating that the TMP461-SP is SEL-immune at LET_EFF = 76.18 MeV-cm²/mg and T = 125°C. Using the MFTF method described in Appendix A and combining (or summing) the fluences of the seven runs (4 × 10⁷), the upper-bound cross-section (using a 95% confidence level) is calculated as:

σSEL ≤ 1.84 × 10^–7 cm² for LET_EFF = 76.18 MeV-cm²/mg and T = 125°C.

Figure 5-1 Current vs Time (I vs t) Data for VCC Supply Current During SEL Run #23