Current to voltage converter with signal at non inverting terminal
Its role is to provide a reference voltage. It is added to Vadc2 to shift the voltage either up or down. Typically these are used with a 2.5V reference to shift a bipolar signal (like ±2.5) to a 0 to 5V range for the ADC (which are typically 5V)

It doesn't have to be 2.5V, it could be 0V (no shift) or another value, usually within the rails of the opamp. 







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