Temperature measurement using thermistor and an ADC
The thermistor is used to detect the change in temperature. There are two types of thermistor, Positive Temperature Coeffecient (PTC) and Negative Temperature Coeffecient (NTC). In PTC type,the resistance increase with temperature and in NTC type, the resistance decrease with temperature. Change in resistance can be converted into electric signal and this analog signal can be converter into digital output using Analog to Digital Converter (ADC).
The conceptual circuit diagram is as shown below
Circuit Diagram (Schematic Diagram)-1
Use these equations to design your circuitry by selecting thermistor and ADC from any of these vendors given far below
N = ADC resolution
b0, b1, and b3 are the temperature coefficients of thermistor.
This is one of the fundamental concept, there are many new innovative idea from the vendors below. Please refer their websites
Analog Device www.analog.com
National Semiconductor www.national.com
Texas Instruments www.ti.com
AdSem, Inc. www.adsem.com
Nichicon USA www.nichicon-us.com
NIC Components www.niccomp.com