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???
07/28/06 12:33
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 		 #121252 - never seen that, but have seen the opposite
Responding to: ???'s previous message
I was wondering if having too many total decoupling capacitors could also cause problems
never seen that, but have seen the opposite (too FEW total decoupling capacitors ) creating problems again and again.

The other thing here is that a decoupling capacitor that is not across the chip with EXTREMELY short traces qualify as "no decoupling of this chip".

I have seen a board where ALL the decoupling capacitors were neatly arranged in a corner of the board and when asked "why do we have these problems" I had a good laugh. The issue was proven by soldering decopuling capa across the individual chips. Then I had them convinced to do a correct layout. I also have had a case where a chip malfunctioned just because the was abou 1" of trace to the decoupling cap.

Erik

List of 25 messages in thread
TopicAuthorDate
Decoupling Capacitors            01/01/70 00:00      
   Paralleling...            01/01/70 00:00      
      Well have a look at the design            01/01/70 00:00      
         I will...            01/01/70 00:00      
            No layout available at the moment            01/01/70 00:00      
               May I ask why you don't follow the reference?            01/01/70 00:00      
                  Because            01/01/70 00:00      
                     No relevant difference, I think            01/01/70 00:00      
                        I do not think so            01/01/70 00:00      
                        try one poured layer for each supply            01/01/70 00:00      
                           Exactly!            01/01/70 00:00      
                              He will need multiple layers anyway            01/01/70 00:00      
                                 Fast clock signals            01/01/70 00:00      
                                 Multiple layers is no joke            01/01/70 00:00      
                                    That's a problem, all right ...            01/01/70 00:00      
                                       Same song second verse            01/01/70 00:00      
                                          Miker, it sounds as if you need to buy a book by D            01/01/70 00:00      
                                          Discontinuities and other mess            01/01/70 00:00      
                                    I wouldn't do that            01/01/70 00:00      
                     This stuff basically hasn't changed in 30 years            01/01/70 00:00      
      I never used individual ferrites ..            01/01/70 00:00      
         You WILL in mixed circuits...            01/01/70 00:00      
   never seen that, but have seen the opposite            01/01/70 00:00      
      Maybe somewhere in between will work            01/01/70 00:00      
   No longer interested, Mike??            01/01/70 00:00      

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