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???
02/03/07 14:44
Modified:
  02/03/07 14:57
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Msg Score: +1
 +1 Good Answer/Helpful		 #131949 - Only at 5V...
Responding to: ???'s previous message
Tom said:
Hello Tom,
For external resets with external crystals, the reset should be long enough for the oscillator to start up (typically 10ms).

That's the standard value, when running at 5V, as I already pointed out here

http://www.8052.com/forum/read.phtml?id=131930

At much lower supply voltage the start-up time can drastically increase, due to increased channel impedance and decreased transconductance (a kind of "gain") within the Pierce oscillator's inverter!!

Again, take at least 100msec as a safe value. Anyway, who cares about the actual reset time in a standard product??

Kai


List of 39 messages in thread
TopicAuthorDate
min reset width?            01/01/70 00:00      
   WHY            01/01/70 00:00      
      why?            01/01/70 00:00      
      Which reset chip, and how long a pulse?            01/01/70 00:00      
      "proper supervisor"?            01/01/70 00:00      
         so why ...            01/01/70 00:00      
            Data Sheet vs User Manual            01/01/70 00:00      
               Data Sheet vs User Manual            01/01/70 00:00      
               wherizit?            01/01/70 00:00      
                  Which uP are you looking at?            01/01/70 00:00      
                     P89LPC932A1            01/01/70 00:00      
                        Hey! Where'd you get Rev 2?            01/01/70 00:00      
                           That's it: I said, it is not in the datasheet/UM!            01/01/70 00:00      
                              Webmaster? They have a webmaster?            01/01/70 00:00      
         Only at 5V...            01/01/70 00:00      
         words, words            01/01/70 00:00      
   Does it not have an internal Reset circuit?            01/01/70 00:00      
      now THIS is a BAD documentation            01/01/70 00:00      
         Does it imply            01/01/70 00:00      
            infernal reset (not a typo!)            01/01/70 00:00      
               So, what's the "right" way?            01/01/70 00:00      
                  don't use it as a port pin            01/01/70 00:00      
                     It's not a pitty but a shame!            01/01/70 00:00      
                        it's "creeping feature"-ism            01/01/70 00:00      
                           not a waste            01/01/70 00:00      
         Yes, I remember those many complaints!!            01/01/70 00:00      
         And what about...            01/01/70 00:00      
            internally timed            01/01/70 00:00      
               I LOVE it            01/01/70 00:00      
                  OK so let's vote            01/01/70 00:00      
                     no voting, please            01/01/70 00:00      
                        this is not taste, but facts            01/01/70 00:00      
   So, how's one supposed to reset this thing?            01/01/70 00:00      
   lets see...            01/01/70 00:00      
      Yes, but what's REQUIRED?            01/01/70 00:00      
   Some results            01/01/70 00:00      
      with or without the reset chip?            01/01/70 00:00      
         now with the reset chips            01/01/70 00:00      
            and the troubles were BEFORE or AFTER?            01/01/70 00:00      

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