ISO7041: ADC ISOLATOR

Hi Tom,

thanks for a quick reply.  I just looked at the design and the power supply is not isolated for both ends. Would you still recommend using AMC1311/ISO224? Even if power supply is not isolated? Is there any TI buffers maybe for that, rather then isolation amps? 
does LM25116MHX requires isolation?
Any thoughts? 

thanks

Hi Sarunas,

Sorry - should have taken a closer look at your schematic.  We do not have the same sort of linear opto, and it doesn't look like you have any high voltage isolation requirements.  That said, we do have the AMC3330 - only one side of the isolation barrier needs power.  Is that closer to what you are looking for?

Thanks Tom, you are very helpful. That AMC3330 is perfect however they out of stock everywhere... 

I will look into what else you have.

By the way, what your thoughts would be replacing isolation with simple TVS and RC filter + diode clamp to protect the inputs. See photo below as indication. Don't look at component values. The ADC chip is used from TI: ADS8668IDBTR

Hi Sarunas,

That would be fine too!  Where is this 30cm cable?  Before or after the resistor divider/diodes?  You need to be aware of the leakage in the TVS/clamp diodes as that would be a source of error in the end. 

HI Tom,

that cable is after all dividers/diodes as it's between 2 PCB's. One PCB is where the voltage is being measured and another PCB has Texas ADS8668IDBTR.  Thanks for that , by error you mean it causes ADC fault or just reading accuracy? As this is not for precise measurements we don't need very accurate result 

No faults, just accuracy - offset error mostly, can be calibrated out.