You need a resistor network to shift the expected input voltage into the range (roughly) GND .. VDDA.
Look at this thread which I found by putting "negative voltage" into the search field at top of this page.
Alqasir, since you already have MAXREFDES5 why not to try it? All it takes is to connect some wires to read an SPI. At the end it all depends on specs requirements: isolation, input range, bit resolution, sampling speed etc.
Perhaps a simpler version is required
using PSoC (TIA +DAC)
ADS7835 ±2.5V Analog Input psoc projects
ads8675 (SPI )
And you can use CY7C65211( PSoC® 4 CY8CKIT-049 ) as an USB to I2C/SPI bridge
Thank you all for replying. The info you provided is very helpful. Do you have a sample working project for the level shifter method?
Something like variant 2 in the picture attached.
tia_opamp (1).PNG 30.5 K