LTC2497

I am reading the analog output from LTC2497.


Setup: Vref+ = Vcc, Vref- = GND.


The conversion is not what is expected.
For <1.2xx v, output = -1
For =<2.0xx v, output = 2.xxx
For =<3.xxx v, output = 0.xxx
For >=3.5xx v, output = 0

Please assist.

Thank you.