adc0831 capture

I have designed a data acquisition system using an adc0831 using the
following pin configuration:
adc0831
1.......................DB25 (RS232) pin 4
2.......................input thru 1k resistor and via 0.1uF to adc pin
3
3.......................to ground and to adc pin 2 via 0.1uF
4.......................to ground
5.......................to +5v (4.91v actually)
6.......................DB25 (RS232) pin 12
7.......................DB25 (RS232) pin 1
8.......................to +5v (4.91v)

The input will be muxed through CD4053 and controlled via the software.

My initial plan was to measure values coming in between 0 and +5v. Now
I want to measure values -2.5 to +2.5, which I gather removes the ground
from pin 3. I learned that the values must be below 5 v but my source
did not stipulate if this is total between pins 2 and 3 (i.e. +2.5 on 2
and -2.5 on pin 3) or 0 to +/- 5 volts on either pin. I read the
datasheet but am not well versed in many of the abbreviations used
there. Could someone straighten me out on this?
Ron

 

My datasheet says input range is 0V - VCC. Therefore if you want to
measure negative voltages you will have to do some level shifting with
an opamp.