My application is a temperature controller that uses a surface temperature sensor and Triac to adjust a heating element using a uC using PID control. Although I only need about a +/- .5 degree accuracy, I'm aiming for a temperature range of 0 to 200 degrees C which seems to be comfortably out of the range of most thermistor solutions but seems to be within the capabilities of a standard RTD.
I'm struggling to implement an RTD in my design as the interfacing solutions I have seen require a lot of opamps and a precise reference voltage. Here's specifically the one I'm talking about from this microchip application note:
My design uses a transformerless power supply that allows me to detect zero crossing as seen in this microchip application note:
I feel like my range and accuracy requirements are modest, do I really need to add regulation for a reference voltage, a constant current source, + and
- voltage sources for op amps in order to use an RTD??? Since I'll be taking my temperature readings in phase with the voltage fluctuation of the power supply, I wonder if regulation for a reference voltage is really necessary. Is there a smoother way to interface with an RTD given my requirements?
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