How does this cross correlation match sensitivity and monte carlo techniques.
Thanks,
Bobmar7
Don't know. If "tolerance" means 95% of the values are within the tolerance limits, then these formulas should give you the interval limits.
I spent a lot of time on a spreadsheet and writing a program to do this, but in the back of a book at Border's [it might have been "Electronics for Inventors" or some such thing] I just recently noticed closed form formulas for calculating tolerances for uncorrelated errors.
These 7 formulas might be on the Web in a lot of different places. The easiest is the Root Sum Square method for adding, which means you can make a 1% resistor from 100 ea. 10% resistors in series. It also works for a series string of LEDs.
You can do it on a spreadsheet by simulating the normal dist. with 10, 20 or 50 values and then operating on each, two values at a time, but it's tedious. I never got my 100 line program to totally work.
Generally, dividing or multiplying two or more normal distributions do not result in another normal distribution, and I know this from the histograms that my spreadsheets produced, but these formulas seem to sidestep that issue. They are just looking for the extreme values, not the shape of the distribution.
The trick is to know that these are called "uncorrelated errors". Since 'formers have mutual inductance, I guess this won't work for them.
My point is, for those who want to produce many of the same analog circuit, these formulas will help pick appropriate component tolerances, depending on your final desired output level tolerance.