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???
05/04/06 16:04
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 		 #115594 - Re: Some Points.
Responding to: ???'s previous message
Dear Kai,

Sorry for my late reply, Actally I was busy with some other project and couldnt work on this.

I have modified my design according to your suggestions. There are still few doubts


- But pi-filters are needed arround ICL7660! Add a ferrite bead an some ohmic resistance between C13 and C13 and exchange C1 by a suited Pi-filter.


Do you mean that I need to put a pi-filter in between the LDO input pin and ICL7660 inverted output. How do I replace C1 by a PI filter I mean the datasheet says a capacitor should be connected?


- For the same reason the circuit arround AVREF needs a change. I would connect AVREF directly to AVCC. To get information about actual value of AVREF you could connect a LM336-2.5V, biased by AVCC, to a free analog input of micro.


In case I connect AVcc directly to AVREF and connect a LM336-2.5 to get actual value of AVREF. How frequency is it required to read the LM336 channel. Is it ok to read the reference channel once at startup or it will be required to read reference channel every time I read my signal input and scale appropriately.

Thanks & Regards,
Prahlad Purohit

List of 42 messages in thread
TopicAuthorDate
Battery powered hand hel mixed signal            01/01/70 00:00      
   Be prepared to make a mistake            01/01/70 00:00      
      Re: Prepared to make a mistake            01/01/70 00:00      
         We're all learning            01/01/70 00:00      
   Some points...            01/01/70 00:00      
      Re: Some Points.            01/01/70 00:00      
         Answers            01/01/70 00:00      
            Re: Answers.            01/01/70 00:00      
               then...            01/01/70 00:00      
                  How much error can it cause.            01/01/70 00:00      
                     Negligible            01/01/70 00:00      
      10uH inductor + 100n            01/01/70 00:00      
         No big time delay is allowed            01/01/70 00:00      
   Modified as per suggestions.            01/01/70 00:00      
      No Cap At SV1.            01/01/70 00:00      
         Voltage drops?            01/01/70 00:00      
            Drop only 0.16V*2=0.32V            01/01/70 00:00      
               F+5V ?            01/01/70 00:00      
                  Re: F+5V & F-5V            01/01/70 00:00      
                     Good, that I aksed...            01/01/70 00:00      
                        Re: What else need changes            01/01/70 00:00      
                        why r7 to avcc.            01/01/70 00:00      
                           Ok            01/01/70 00:00      
                              Re: Capacitor with LM336            01/01/70 00:00      
                              You could do...            01/01/70 00:00      
                                 re: you could do.            01/01/70 00:00      
                                    What I meant            01/01/70 00:00      
                                       re: what i meant.            01/01/70 00:00      
                                          Present layout            01/01/70 00:00      
                                             Additionally...            01/01/70 00:00      
                              How do i connect protection diode to AVc            01/01/70 00:00      
                                 Like D3            01/01/70 00:00      
                                    Why do I need a diode.            01/01/70 00:00      
                                       credit for design            01/01/70 00:00      
                                          Thanks!            01/01/70 00:00      
                                       From ADC7-input to AVCC            01/01/70 00:00      
         Is needed            01/01/70 00:00      
            Re: Cap needed.            01/01/70 00:00      
   Modified final layouts.            01/01/70 00:00      
   I fixed your layout            01/01/70 00:00      
      Looks nice...            01/01/70 00:00      
   Design sent for PCB making            01/01/70 00:00      

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