Totally off the top of my head but possibly worth a look ...... use the=20 thermistor in part of an oscillator then measure the time period or number= =20 of pulses in a fixed time period. You could also use the PIC output pins to switch in/out various bias=20 resistors for the divider network depending on the measured temperature at= =20 the thermistor - you may not get the exact 3.3v at the pin but you should b= e=20 able to work around it enough to get a reasonable reading. Could be worth a look, could be a dead end. Dom ----- Original Message -----=20 From: "alan smith" To: "Microcontroller discussion list - Public." Sent: Tuesday, February 07, 2012 8:36 PM Subject: [EE] increasing sensitivity of a thermistor hi group..me again I want to bounce something off the members. So I have a board that I designed with a 10K thermistor, but its feeding a 3.3V micro (and that is fixed...cant change=20 this part). They have come back and asked for a better resolution. Now a thermistor, it simply generates a voltage as a divider with a source impedance of course. As the temperature changes,= =20 the voltage that is generated across it changes, and the resolution of what you can measure is going to be dependent on the source voltage as=20 well as the ADC resolution. So the ONLY way to get better resolution is to be able to increase the source voltage from 3.3V to 5V or use a higher resolution ADC. Now for either case, the micro thats reading this is 3.3V, so using 5V is out of the question. Sorta thinking....using a PIC running at 5V to read the thermistor, and then either using a PWM output (with RC filter) to= =20 regenerate a voltage of controlled steps over the temperature range they want to=20 measure (pretty sure its 0 to 100F) for the ADC in their part to measure. Any other possible clever ideas? --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist=20 --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .