Other Parts Discussed in Thread: ADS1248
Hello,
I am currently starting the development of a schematic based on the ADS124S08 for thermocouple (Type K) application. The intention is to use one ADS124S08 to read 5 Thermocouples and leave the additional channel for the CJC. As CJC I plan to use a RTD SMD PT100 (https://www.heraeus.com/media/media/hne/datasheets/smd/en_12/smd_0805_v_e.pdf) with obviously just 2 leads. I have looked for reference designs and I have seen 2:
1) On one hand the reference design to be found for the ADS1248. In this case for a 3-lead RTD (page 83, see below):
2) On the other hand a design in the ADS1x4S08 Evaluation Module (page 22 SBAU272A, see below):
As additional information to my application, I intend to use a single +3.3V supply between the AVDD/DVDD and AVSS / DGND (0V) and the internal reference only.
I see differences between both schematics, specially in regards to the use of IDAC1 only or IDAC1+2 and its connection to the RTD. Could you guide me a little bit and explain which should be the most suitable one to use as basis for my application and why?
Thanks,
Javier