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???
08/31/06 15:52
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 		 #123450 - it will work...
Responding to: ???'s previous message
... just throwing out the 1Ohm resistor (removing the 50mV drop) was enough.

We already manufactured several hundreds of these boards and all were OK. Similar designs (combination of ADM707 and 7805) works well in other hundreds of boards.

During the last 15 years I have measured hundreds of 78x05s ranging from Tesla packaged in the tank-like TO3 through anonymous noname suspicious-looking TO220s with absolutely no marking to the tiny 78L05s; and I've NEVER seen less than 4.95V (and more than 5.05V) and even less than 4.98V was really rare. I believe, the manufacturing tolerances today are much more better than they were 20 years ago or when was the 7805 concepted - and I suspect that what we had here were rejects (maybe from you, Kai? :-) )

Jan Waclawek


List of 44 messages in thread
TopicAuthorDate
78x05 output voltage tolerance            01/01/70 00:00      
   5%            01/01/70 00:00      
   Selection needed...            01/01/70 00:00      
      5%, 10%, it's all there            01/01/70 00:00      
         for decades, 5% was "standard." What's changed?            01/01/70 00:00      
         What standard do you mean??            01/01/70 00:00      
            "if"            01/01/70 00:00      
               Don't you test your circuits?            01/01/70 00:00      
                  it's already a pain...            01/01/70 00:00      
                     if you do, I'll take my cap off to you :)            01/01/70 00:00      
                  Consider the specifications            01/01/70 00:00      
   is it a Microchip supervisor?            01/01/70 00:00      
      the conclusion            01/01/70 00:00      
         No such thing as luck in any acceptable design sce            01/01/70 00:00      
            everyday we learn something...            01/01/70 00:00      
         Check it with a >5.0V outputting 7805!            01/01/70 00:00      
            it will work...            01/01/70 00:00      
               oh 'testing'            01/01/70 00:00      
            Getting more than 5 v from 7805            01/01/70 00:00      
               I would use a resistor instead of a diode            01/01/70 00:00      
                  see the datasheet, it shows how to do that...            01/01/70 00:00      
                     It's noise, I guess...            01/01/70 00:00      
                        some noise            01/01/70 00:00      
               the u (micro) is only specified to 5.25 or 5.5 Vol            01/01/70 00:00      
   I just had an idea...            01/01/70 00:00      
      Don't go off chasing that rabbit!            01/01/70 00:00      
         digital design practice            01/01/70 00:00      
            Safe side...            01/01/70 00:00      
         Exactly            01/01/70 00:00      
      Getting low output...            01/01/70 00:00      
   get this in your head            01/01/70 00:00      
      Not so fast...            01/01/70 00:00      
         oh, how many designs have failed because            01/01/70 00:00      
            No, no, I have not said this            01/01/70 00:00      
            it depends on the source ...            01/01/70 00:00      
               Yes,...            01/01/70 00:00      
                  There's a critical difference ...            01/01/70 00:00      
                     Of course, there is!!            01/01/70 00:00      
                        whst do you refer to?            01/01/70 00:00      
                           This was in the '70's, before many restrictions            01/01/70 00:00      
                              caught by "legal relabeling".            01/01/70 00:00      
                                 That's not what I remember            01/01/70 00:00      
                                    continuing the story            01/01/70 00:00      
                                       The way it used to work ...            01/01/70 00:00      

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