How to use LM34 to full range with PBP

[Charles Linquis]

You can do this several ways.

But probably the best way is the method given in a National Semi application note: Put two diodes between the "-" terminal of the LM34 and GND. This offsets the voltage by about 1V. You will also note that - because the diodes have a temperature coefficient of their own, you should also measure the voltage at the junction of the diodes and the LM34 and take a differential reading. Of course, this will take two channels of A/D.

Look for National Semi Application Note AN-460, and check out Figure 10.

[Charles Linquis]

And yet another method that I have used:

Your system probably has a precision reference voltage (for example: I use a 4.096V reference for the A/Ds). Use a resistive divider off that reference to give you about 1.0V, and then buffer that voltage with an op-amp. Use the output of the buffer for the negative supply of the LM34.