Trends of IEMI Induced Upset on Different Microcontroller Devices

Using a state-of-the-art automated testing system called SALVO, pulsed RF signals - referred to as Intentional ElectoMagnetic Interference (IEMI) - were direct-injected onto the clock line pin of 4 separate Microcontrollers (MCU) using careful timing. The MCUs were programmed in Assembly language to execute a simple binary counting operation, which counted from 0 to 7. The MCU’s output lines were monitored to verify the count value and determine whether the IEMI caused upset. Waveform characteristics such as frequency, power, pulse width, and injection time, were varied to explore the trends of upset for each device. Probability of Upset (PoU) was computed by holding one variable constant, while varying the others, then taking the number of upsets observed over the total number of samples collected. It was determined that an above 80% PoU was achieved in frequencies between 25MHz and 800MHz when the power was greater than 8W. Pulse widths greater than 100ns showed best performance; However, pulse widths exceeding 400ns did not provide a significant increase in PoU suggesting a diminishing return threshold above this value. Finally, injection of the IEMI during clock rise and fall edge times - regardless of the instruction being executed - showed the highest PoU. However, MCU4 did not conform to this trend - likely because it executes instructions in parallel - and highest PoU during clock high times.