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???
12/02/12 12:31
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 		 #188942 - Power-on slope rate...
Responding to: ???'s previous message
Richard said:
I've done a limited amount of fiddling with the notion of controlling the rise and fall of Vcc, using transistors to pull down Vcc to the MCU whenever RESET goes active, but I've not convinced myself that all the bases are covered when that's done.

Power-on slope rate should be something between about 0,01V/msec and 10V/msec, dependent on actual micro. Not faster and not slowlier. A microcontroller is a hihgly dynamically working thing. Many hidden micro subroutines are running in the behind, charge pumps, oscillators, sequencers, etc. I'm sure that the developers of microcontrollers need a certain narrow window of power-on slope rate to manage all these internal issues when powering up the micro. And Vcc should start from 0V on...

Kai Klaas

List of 33 messages in thread
TopicAuthorDate
C8051F231 experiences            01/01/70 00:00      
   another solution            01/01/70 00:00      
   The probabilities are low...            01/01/70 00:00      
      think about what happens when you add a finger            01/01/70 00:00      
         The point is ...            01/01/70 00:00      
            Yes ... the underlying issue is the flash ...             01/01/70 00:00      
               Out of my office, but...            01/01/70 00:00      
                  Don't think in Vcc, ESD or hum...            01/01/70 00:00      
   Apparently several C8051F2xx parts have the same pinout            01/01/70 00:00      
   Characteristic for in system programmable flash micros...            01/01/70 00:00      
      All too true ... sadly ...             01/01/70 00:00      
         Power-on slope rate...            01/01/70 00:00      
            Sorry, my post should be here, no up there...            01/01/70 00:00      
            Have you any basis for that rate?            01/01/70 00:00      
               Vdd ramp time            01/01/70 00:00      
               Some datasheets show numbers...            01/01/70 00:00      
                  Those aren't the "usual" 805x-core MCU's            01/01/70 00:00      
                     There aren't many "usual" 8051-cores anymore...            01/01/70 00:00      
                        How dangerous power ups can be...            01/01/70 00:00      
                           I believe it            01/01/70 00:00      
                              (dV/dt) examples            01/01/70 00:00      
                                 They don't know it either...            01/01/70 00:00      
                                    dV/dT etc             01/01/70 00:00      
                                       reset request...            01/01/70 00:00      
                                          That's what disturbs me greatly            01/01/70 00:00      
                                             It IS disturbing!            01/01/70 00:00      
                                                Where this began ... at least for me ...             01/01/70 00:00      
                                                   So, you took the hard road...            01/01/70 00:00      
                                                      We've all had that experience             01/01/70 00:00      
   probable cause            01/01/70 00:00      
      Brent, this is very nice            01/01/70 00:00      
         forum no longer down            01/01/70 00:00      
      Thank you!            01/01/70 00:00      

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