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???
05/24/07 08:43
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#139727 - grounds etc
Responding to: ???'s previous message
Chinmay Nanda said:
What i have in mind is that i would design two separate boards for digital and analog. digital section -which will only have the uc with related circuitry ,this section will be connceted to another board with DAC and ADC on them with the isolators via a FRC connector.
1> do i still need to join the GND 's of these two boards?wont it defeat the purpose of isolation


You MUST join the grounds together. You can't have one board floating with respect to the other.

3> I will be grateful if someone could give me some ref. or link which clarifies the concept of isolation.


Here's a thought. You're probably overly paranoid about "isolation." If you are careful with your layout, you can put your micro AND your converters all on the same board, with the same ground plane, and meet your desired performance specs.

Note the comment, "careful with your layout." As Erik and Kai note, you MUST do a multilayer board. You'll want to provide separate power supplies for the analog and digital components. But you can use one ground plane for everything ... if you ensure that your digital traces never cross sensitive analog signals and if you basically have distinct digital and analog areas of the PCB.

Good luck.

-a

List of 37 messages in thread
TopicAuthorDate
need for isolating signals            01/01/70 00:00      
   avoiding the inverter            01/01/70 00:00      
      sinking the current            01/01/70 00:00      
         Sinking and sourcing            01/01/70 00:00      
            the bulb blinked !!!            01/01/70 00:00      
               Don't guess!            01/01/70 00:00      
                  trnasfer char.            01/01/70 00:00      
                     Transfer characteristic            01/01/70 00:00      
   More so            01/01/70 00:00      
   I see two possibilities            01/01/70 00:00      
      accuracy            01/01/70 00:00      
         0.01% approx 14 bits            01/01/70 00:00      
         Hardly...            01/01/70 00:00      
   No need...            01/01/70 00:00      
      need to place inverter            01/01/70 00:00      
      my design            01/01/70 00:00      
         FRC?            01/01/70 00:00      
            FRC?            01/01/70 00:00      
               or may be this......            01/01/70 00:00      
                  Not really            01/01/70 00:00      
                  Flat Ribbon Cable connector            01/01/70 00:00      
               FRC Connector!            01/01/70 00:00      
            You don't know the Flat Ribbon Cable?            01/01/70 00:00      
               Not by that name!            01/01/70 00:00      
         FAQ: How to post pictures?            01/01/70 00:00      
         you are grasping for straws            01/01/70 00:00      
         sure, but to what use            01/01/70 00:00      
         grounds etc            01/01/70 00:00      
            not entirely correct            01/01/70 00:00      
               single plane            01/01/70 00:00      
                  A very well qualified layout person can do 'magic'            01/01/70 00:00      
                     but he can hardly outsmart the laws of physics            01/01/70 00:00      
                  Nevertheless, there IS a difference            01/01/70 00:00      
                     the difference            01/01/70 00:00      
                        Yes, yes, yes, but...            01/01/70 00:00      
   Aside: Other Isolation Technologies            01/01/70 00:00      
   no response            01/01/70 00:00      

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