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Old 13th June, 2004, 11:49 AM
Aedan Aedan is offline
Chief Systems Administrator
Join Date: September 2001
Location: Europe
Posts: 13,075

From what I know about electronics, the biggest problem with a brown out is the fact the PSU can no longer maintain the correct output voltages. The internals of whatever device will be trying to operate on a voltage that may be too low for them to operate correctly. It is possible that components can then end up in a situation called 'latch-up'. For digital devices, this usually represents the output trying to switch to both '0' and '1' simultaniously. The net result is that the device tries to short out the power supply. Obviously this leads to dead components fast!

For analog devices such as op-amps, it's a similar story in that the component tries to connect both the positive and negative supplies the the output at the same time. If the op-amp happens to be part of the power supply, then your power supply may end up throwing out odd voltages, and killing things connected to it. (There are techniques to help prevent this, but they're all fairly brutal to the PSU.)

Surges and spikes cause problems due to the rather high voltages that can appear on the mains. In industrial areas, spikes on the mains can easily exceed 1000V - you have to hope that your PSU is well enough protected to prevent problems. Surges tend to be smaller in size than a spike, but tend to be longer events. Devices like surge protectors are all very good, but the cheaper ones use a device called a MOV. These are pretty good at absorbing excess power, but with a large surge/spike the MOV may sacrifice itself to absorb the excess power. After this occurs, the MOV is dead, and can't provide any further protection from surges/spikes!
Any views, thoughts and opinions are entirely my own. They don't necessarily represent those of my employer (BlackBerry).
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