Other Single Event Effects

Spurious Pulses

In analog circuits like the operational amplifier below, the output voltage will spike. Depending on the speed of the amplifier and the circuit, the output can settle smoothly back to the original voltage or temporarily oscillate, as shown in this output waveform. These spurious pulses can propagate through other circuits and cause errors in received command data, errors in transmitted telemetry, or false readings on sensors.

Permanent Destruction

A HEXFET is a type of transistor that is designed to switch large amounts of voltage and current. A HEXFET is actually made up of thousands of smaller transistors that work collectively to handle the large load. When a particle causes one of these small transistors to turn on by itself, that transistor bears the brunt of the large load by itself and burns out, often destroying the device.

Even devices that don't contain memory elements can suffer from a form of single event upset. Until recently, very little research has been directed towards the study of other Single Event Effects. These SEEs can take several forms.

In combinatorial digital circuits (circuits with no memory), the result is usually a glitch, or a temporary change-of-state of the output. A glitch usually lasts anywhere from a fraction of a nanosecond to several nanoseconds, and can cause problems in circuits that are downstream. For instance, if a circuit that drives a counter experiences a glitch, the counter may increment, causing the counter value to be inaccurate.

Temporary Nonfunctionality

Sometimes SEEs cause parts to cease functioning. Possible causes include a mild latchup condition where only small sections of the chip are disabled, or the occurrence of bit-flips in control logic. Parts often have diagnostic modes that disable the device and provide self-test data for use during manufacturing. By the time such a device is shipped to the end user, these special modes are disabled so that the device is always functional. However, a bit-flip can cause the part to enter one of its diagnostic modes, making it seem nonfunctional. Diagnosing and analyzing part failure in such a circumstance is very difficult.

In most cases where a part becomes nonfunctional with no apparent power increase (vs. the latchup condition where large current draws occur), the part will function again if power is removed and reapplied.