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09/01/05 12:42
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 		 #100412 - Because some app engineer tries to make
Responding to: ???'s previous message
I designed in with the LED circuit suggested by Philips, sourced from the +5V, I think the +5V comes up on the port pins of the LPC921 before the +3.3V is fully stable on the Vdd pins of the LPC921.
Because some app engineer tries to make toy manufacturers that have no need for reliability use the chip see a dirt cheap solution does not mean it is right. Just see e.g. the RD2 datasheet with a) RC reset circuits and b) a note: if you use RC reset, you may lose the code. The LED circuit MAY work most of the time, but to rely on it as totally reliable is dumb. As to 5V on 3V3 pins, I know you can but I do not want to deal with the problems associated with that (reduced noise immunity, incresed prop delay etc). I use HCT for 3V3 outputs and 74LVC4245 for 3V3 inputs so I can not comment on whether that is a problem.
Is your 5V stuff not available in 3V3?

I am planning to design a robust power supply for the LPC921 and start all over again, with proper programming tools
GREAT

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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