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Need help isolating ADC inputs

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royco

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What is the best way to isolate ADC inputs from one another?

I have an application where I need to measure voltage from different systems with different GND levels that I would like to keep isolated. Whats the best solution for this? I have been looking at the linear opto isolators like the LOC110 but have no experience with their linearity. Can differential amplifier op amps be used in this situation?

Voltages that I need to measure are in the 48v range.

Thanks
 

You can isolate them with buffer
 

OR configure the input pins of the ADC differently by configuring the registerasof the ADC........
Regards,
Jerin.
 

John, jerin,

Thanks for the reply. Can you show me examples or a schematic on how to do it? Im new to these stuff. Most that ive searched for buffers are for full differential adcs and im using a single ended adc.

Also, hwo do i make the adc read the voltage even if the source is reversed? Similar to DMMs showing negative numbers?

Thanks

Roy
 

I can get you to the basic ADC circuit schematic simulated in PROTEUS & the asm code. Do the same procedure with PIC18F4620 by reffering its data sheet & do try to make up the ADC circuit.
Do check the code & schematic in PROTEUS.
Regards,
Jerin. :)
 

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Thanks I will try that when I get home.
 

Another option is to build small, single-channel ADC blocks that are fed through isolated dc/dc converters and “talk” to them via normal optocouplers .. 3-wire or I2C ..

IanP
:wink:
 

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