MCP3423 Negative VSS

Good evening all,

I'm trying to read negative voltage from MCP3423. I've seen that it's possible to do it if you set VSS to a negative voltage, so I did it.

The problem comes when I try to read from it. If I use GND as VSS it all goes ok, but if I change vss to -3.3 the device doesn't even answer.

Does anyone know how to read negative from MCP?


You cannot put -3.3V at the Vss pin.
You may destroy your chip.
Vss must be wired to Gnd=0V.

The adc can do "differential reading" - it means you may get negative readings when CH1+ is lower than CH1-.

But CH1+ nor CH1- cannot exceed Vss=0 and Vdd (in other words, both CH1+ and CH1- must be within 0..Vdd).

Tell us what you want to measure. My crystal ball shows a CO2 sensor.
The solution might be a level converter with opamp, or a voltage divider connected to VCC.