OBSERVATIONS OF SINGLE-EVENT UPSETS IN NONHARDENED HIGH-DENSITY SRAMS IN SUN-SYNCHRONOUS ORBIT

Observations of single-event upset (SEU) activity in non-hardened static and dynamic RAMs of both low (16K-bit) and high (256K-bit, IM-bit) density are presented for a family of small spacecraft in low-Earth, near-polar, Sun-synchronous orbits. The observation of single-event multiple-bit upset (MBU) in these devices is discussed and the implications of such events for error-protection coding schemes are examined. Contrary to expectations, the 1M-bit static RAMs (SRAMs) are observed to be more resilient to SEU than the 256K-bit SRAMs, and in particular, one type of commercial 1M-bit SRAM shows a particularly low error rate.