[SI-LIST] : App note assumptions

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From: Mark Geddes (mark@AudeSi.com)
Date: Fri Apr 14 2000 - 12:31:34 PDT


Has anyone else noticed in this "app note" (see below) that Cypress has a
very good
scientific explanation about why using several values of decoupling
capacitors can cause problems, and then they go on to recommend a bunch of
general routing rules that they haven't substantiated?

This is how false information is spread.

1+1=2, because if I have one cow in a field, & then put another cow in that
field, I will have two cows in the field. Therefore use one cap per power
pin, 1+1=2, place caps close to the IC & on the same side, and keep leads
below 6mm. Can anyone pick out the assumptions I made after giving an
example why 1+1=2?

Thanks Lee Ritchey, for making me skeptical of app notes!

Mark Geddes

>
> What worries me about using bulk capacitors with different capacitance
> in parallel as in the picture you sent is well described in
> the following
> article:
> http://www.cypress.com/pub/appnotes/decouple.pdf
> (look especially picture 5 on page 3)
>

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