I am designing a circuit that needs to have 18 thermistors to measure the temperature at various points. The thermistors are 2metres+ away from the ADC
Usually when I power a thermistors I use a Vref IC and an opamp buffer. I also take the op-amp buffer into the ADC ref for ratiometric measurement. With 18 Thermistors and 2-3mA per thermistor, that's getting up to 50mA+ and beyond the current output of op-amp buffers.
How should I do this many thermistors in parallel? Should I split them up into say 3 blocks of 6, with 3 six channel ADCs and have 3 op-amp buffers from the Vref?
Or should I do all 18 at once with 1 op-amp buffer
Should I even be using an opamp buffer?