Hi,
I am currently working on a board which will sample 4 Pt100 RTDs.
Required sample rate is low but highest accuracy is required. This is not operating in an industrial environment, but nearby a 15A load is controlled by phase angle (50Hz).
Currently I am looking at using the LMP90100 to sample the RTDs.
Referring to the device datasheet, there are two example topologies given for 3-wire measurements. One uses 2 current sources and the other uses 1.
My question is; what are the advantages of using 2 current sources vs 1, in terms of accuracy?
I see that 2 sources has the advantage of a single channel measurement per sample, but the current source mismatch may introduce an error. In my design this means 4 ADC chips.
I see that 1 source requires 2 channel measurements per sample, and the timing difference between these two measurements may introduce more RF noise in the sample. In my design this means 2 ADC chips.
What else am I missing in my assessment of this?
Thanks in advance,
Darrin.