Quote Originally Posted by mackrackit View Post
Another idea if you do not want the extra hardware and will give up a little bit of resolution.

I had the same problem in the past, using a LM34 and a pressure sensor with an output of 1 to 5 volt = 0 psi to MAX. Left the VREF at VDD. OK for the pressure sensor, took the ADC value from the LM34 *2. This gave a 2 degree resolution for the temperature though, and I can not remember but I think the ice water test was off a degree or two also.

Not perfect but the pressure was the critical thing on that application.
Or instead of scaling up the lower voltage sensor, you could keep the lower voltage Vref, and run the higher voltage sensor output thru a resistor voltage divider network to scale it's voltage down to the lower one.