Origin of 10-90% Rise Time?

Thread Starter

user117

Joined Jun 13, 2018
1
I'm in the process of writing a report that includes rise time measurements, and I can't seem to find where the convention of rise time defined as 10-90% of bilevel comes from... It seems rather arbitrary to me. It seems like a poorly founded standard for over damped systems.

I see that the 2.2*tau for RC rise time is derived from the 10-90%, but where does the 10-90% itself derive from?

Any knowledge/thoughts would be appreciated!
 

wayneh

Joined Sep 9, 2010
17,496
It seems rather arbitrary to me.
I don't know the real answer, but your intuition sound right to me. You have to pick some definition, and that range sounds reasonable. A choice of 5 to 95% would probably have problems with noise and measurement error, while 20 to 80% would cover barely more than half the full range.
 

bertus

Joined Apr 5, 2008
22,270
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