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???
08/12/05 17:46
Modified:
  08/12/05 17:50
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 		 #99299 - maybe
Responding to: ???'s previous message
Can a LPC9xxx part driven through an led from a +5v (7805 etc) adequately decoupled, say with a 10uF and a 100nF caps be termed as "proper"?
NO, ABSOLUTELY NOT

If you use a proper regulator such as LM2937-3,3 to achieve the 3v3, then maybe.

There is more to a power supply than the regulator. No linear regulator is "proper" if it is not fed (more than) the minimum input voltage.
I have seen 7805 circuits go bonkers when the input voltage dropped slowly after power off (do not remember the brand - switched to switchers ages ago).

I can imagine that when using a linear (again it was long ago) that a bleeding resistor - say, 100 ohms - on either side of the regulator may be beneficial.

Erik

List of 75 messages in thread
TopicAuthorDate
LPC900 (932) series how reliable?            01/01/70 00:00      
   LPC reliability.            01/01/70 00:00      
      there was never a problem with reliabil            01/01/70 00:00      
      Power cycling not below 0.20V ?            01/01/70 00:00      
         I do not know this for a fact, but my im            01/01/70 00:00      
         VPOR            01/01/70 00:00      
            POR and other things            01/01/70 00:00      
               That's an absurd behaviour            01/01/70 00:00      
                  Yea.            01/01/70 00:00      
                  Why not an external supervisor.            01/01/70 00:00      
                     use of an external reset            01/01/70 00:00      
                  only an issue for the internal reset            01/01/70 00:00      
                  Exactly            01/01/70 00:00      
                     yes, we understand            01/01/70 00:00      
                        most companies I know have "idiots" to a            01/01/70 00:00      
                        Very good to hear!            01/01/70 00:00      
                           other plans            01/01/70 00:00      
                              rumors            01/01/70 00:00      
                                 its not a rumor anymore !            01/01/70 00:00      
                                    and for those of you that need .1" pin s            01/01/70 00:00      
                                    How about a USB version?            01/01/70 00:00      
            Power Supervisors.            01/01/70 00:00      
               Handling 932 devices            01/01/70 00:00      
                  Could 3V devices have these problems?            01/01/70 00:00      
                     I have used both the LPC and the SILabs            01/01/70 00:00      
                     Reset post-production            01/01/70 00:00      
                        I have no doubt that marketing forced th            01/01/70 00:00      
                     why not the 5V devices?            01/01/70 00:00      
   LPC9xx Reset Conclusion            01/01/70 00:00      
      A very good question!            01/01/70 00:00      
         I have had zero problems, but am, for ot            01/01/70 00:00      
         Our solution            01/01/70 00:00      
            Pinch circuit            01/01/70 00:00      
            Pich Circuit.            01/01/70 00:00      
               Curing the symptoms!            01/01/70 00:00      
                  once more            01/01/70 00:00      
                     How " proper" is proper?            01/01/70 00:00      
                        maybe            01/01/70 00:00      
                           I thought so too            01/01/70 00:00      
               I haven't forgotten..            01/01/70 00:00      
                  We are waiting desperately            01/01/70 00:00      
                     Simple, but current consuming            01/01/70 00:00      
                        Space consuming & Costly.            01/01/70 00:00      
                           Availability...            01/01/70 00:00      
                              Already using in a product.            01/01/70 00:00      
                                 Tomas Stein has more experience with LPC            01/01/70 00:00      
                              Excellent statement!            01/01/70 00:00      
                        Is it foolproof.            01/01/70 00:00      
                           Active low for the duration of reset            01/01/70 00:00      
                              Re: Active low            01/01/70 00:00      
      Problems with LPC922 at start-up            01/01/70 00:00      
         not at all, what they (try to) say is th            01/01/70 00:00      
            Quartz            01/01/70 00:00      
         glitch?            01/01/70 00:00      
            Factory mode            01/01/70 00:00      
               more factory modes            01/01/70 00:00      
                  Factory mode : Perhaps...            01/01/70 00:00      
                     I was just guessing...            01/01/70 00:00      
                        Philips chips use reset as an OUTPUT whe            01/01/70 00:00      
                           reset OUTPUT?            01/01/70 00:00      
                              I did not look and thus I stated " My gu            01/01/70 00:00      
                        It's worth a try...            01/01/70 00:00      
                           It may be an idea to e-mail Bauke Sideri            01/01/70 00:00      
                              No contact available...            01/01/70 00:00      
                                 Their e-mail must have been abused, it u            01/01/70 00:00      
         btw.            01/01/70 00:00      
   Supervisor & Watchdog ?            01/01/70 00:00      
      a watchdog is not needed to ensure a rel            01/01/70 00:00      
         Purchased another 20 Nos of LPC921            01/01/70 00:00      
             Now, if you have trouble getting it, ho            01/01/70 00:00      
               Already tried that...            01/01/70 00:00      
                  Because some app engineer tries to make            01/01/70 00:00      
                     Adding more devices for reliablity            01/01/70 00:00      
                        Where is the connction?            01/01/70 00:00      
                           Sorry!            01/01/70 00:00      

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