I need some help to choose resistor for voltage divider circuit to read temperature using NTC Thermistor. I'm planning to use STM32 with his 12bit ADC.
The NTC I'm using has the following properties:
- Sensing Element: Thermistor NTC
- No-load resistance at 25°C: 10Kohms
- Tolerances at 25°C: ±1%
- Beta(25/85) Constant: 3977K ±1%
- Operating temperature range: -40C ÷ 125C
More information available here: Datasheet.
The temperatures I will be measuring are between 15C and 65C.
I'm planning to build a simple circuit like this:
What would be a good value for Rs for this conditions? I believe is better to use the 3.3v rail instead of 5v from STM32, is that correct?
I think with this circuit when temperature raises the voltage on Vout will decrease. I also saw some designs where Rs and Rt are flipped. Is there any advantage of the other (flipped) approach? With this approach I believe I can pass less current on Thermistor as ideally should be max 1mA.
Can I get reasonable good precision with circuit like this or shall I consider noise cleaning with capacitor or more complex circuits using OpAmp etc?