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???
03/31/07 13:48
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 		 #136306 - 'testing' revisited
Responding to: ???'s previous message
The crystal can still be the cause of your problems, which might be hidden now by a better DS1307 which is less sensitive to the poor crystal characteristics!
I second Kai on this one.
It is imminently possible that you have two DS1307's that both are WITHIN the ranges specified in the datasheet and one of them is "to one side of the specs" enough to make a marginal crystal work. If this is a one-off, well, then let dead horses lie, but, if not, then you NEED to verify that the first DS1307 is, indeed, defective. The fact that the first DS1307 worked when 5V powered makes it even probable that it was 'good'.One thing that strikes me here is that the appnote spend more discussion on crystal 'quality' than the xtal discussions for any other use of an xtal I have seen.

Erik

PS I am not a chip designer, but I can see that at 'ultra low power' the tolerances should be quite a bit wider than otherwise.



List of 34 messages in thread
TopicAuthorDate
DS1307 back up problem            01/01/70 00:00      
   backup problem            01/01/70 00:00      
   To Pradheep            01/01/70 00:00      
      back up problem            01/01/70 00:00      
         Are you sure?            01/01/70 00:00      
   Are you sure...            01/01/70 00:00      
   Something else            01/01/70 00:00      
      To Jon            01/01/70 00:00      
         Have a look at this            01/01/70 00:00      
            seems?            01/01/70 00:00      
               Help me            01/01/70 00:00      
                  Extract fron the datasheet            01/01/70 00:00      
         Open Drain Output            01/01/70 00:00      
   Crystal            01/01/70 00:00      
      To a different kind?            01/01/70 00:00      
         crystal            01/01/70 00:00      
            In the link            01/01/70 00:00      
               pull up            01/01/70 00:00      
                  Yes, but...            01/01/70 00:00      
      Yes, looks like a poor crystal...            01/01/70 00:00      
         Power Up / Down            01/01/70 00:00      
            Problem Solved            01/01/70 00:00      
               Not so fast...            01/01/70 00:00      
                  'testing' revisited            01/01/70 00:00      
                     The same thought I !            01/01/70 00:00      
               request            01/01/70 00:00      
                  Learn to debug            01/01/70 00:00      
                     Very useful post, Andy!            01/01/70 00:00      
                        Other part of rule #1            01/01/70 00:00      
                        a great goal, do you achieve it every time ?            01/01/70 00:00      
                           Revision Letters            01/01/70 00:00      
                           Here's how            01/01/70 00:00      
                              and pay $25,000,000 to the descendants            01/01/70 00:00      
                        Hopefully, it leads that way            01/01/70 00:00      

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