Email: Password: Remember Me | Create Account (Free)

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
???
08/14/07 05:32
Modified:
  08/14/07 05:32
Read: times


 		 #143242 - the mysterious data loss in BBRAM
Richard,

I am starting this thread specifically to discover the root of the data loss problem in the BBRAM under falling VCC. I am perhaps more interested in finding the root cause of this than you are.

Almost in all equipment I came accross and I was involved in designing, battery-backup is used for data SRAM, and we have had numerous cases of data loss, incidental and regular. However, we managed to solve all of those "mysteries" so far. Some of them resulted from problematic and marginal design; others from faulty devices or bad handling of the boards (shorted battery, for example)(this is very unlikely in your case).

This, of course, requires your cooperation.

Could you please present here (part of) drawing of the circuit you were using for your experiments, including chipselect and VCC routing and all other details which might be relevant. A photo would be very helpful, too.

Jan


List of 39 messages in thread
TopicAuthorDate
the mysterious data loss in BBRAM            01/01/70 00:00      
   I just used the Dallas parts!            01/01/70 00:00      
      I've heard only praises to the Dallas chips, too..            01/01/70 00:00      
         I agree re Dallas            01/01/70 00:00      
            another method            01/01/70 00:00      
               I don't understand            01/01/70 00:00      
                  nah            01/01/70 00:00      
                     ... I just would expect that..            01/01/70 00:00      
                        You are absolutely right, of course!            01/01/70 00:00      
                     You should dig deep when posting here!            01/01/70 00:00      
                        nope, but ...            01/01/70 00:00      
                           But, what if your post is just wrong??            01/01/70 00:00      
                              well, it was not            01/01/70 00:00      
                                 What has this to do with Jan's application??            01/01/70 00:00      
                                    everything            01/01/70 00:00      
                                       When you use a second supervisor chip, ...            01/01/70 00:00      
                                          it does - IF            01/01/70 00:00      
                                             For occasional writes you have the FLASH            01/01/70 00:00      
                                                this depends on application, too            01/01/70 00:00      
                                                   But why??            01/01/70 00:00      
                                                      early power fail interrupt .....            01/01/70 00:00      
                                                         this is the purpose of reset            01/01/70 00:00      
                                                            Sadly, there's no guarantee it does that!            01/01/70 00:00      
                                                               ensure the same voltage on mcu and RAM/supervis            01/01/70 00:00      
                                                               yeah, sure            01/01/70 00:00      
                                                            OK, once more            01/01/70 00:00      
                                                               given a proper ground and power plane ...            01/01/70 00:00      
                                                         I have to agree ...            01/01/70 00:00      
                                             this depends on application            01/01/70 00:00      
                                             There's room for doubt ...            01/01/70 00:00      
                                       thanks            01/01/70 00:00      
                                 sounds reasonably            01/01/70 00:00      
   Pull-downs at inputs of battery powered CMOS-RAM            01/01/70 00:00      
      Observation technique affects the outcome            01/01/70 00:00      
         Some comments and two questions            01/01/70 00:00      
   Designing a pre-test environment ...            01/01/70 00:00      
      Eager to hear the results!            01/01/70 00:00      
         You'll have to be patient ...            01/01/70 00:00      
   Has anyone tried THIS?            01/01/70 00:00      

Back to Subject List