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TIDA-00110: Accuracy of the board

Yash Kudale
Prodigy 55 points
Part Number: TIDA-00110
Other Parts Discussed in Thread: ADS1248, ADS1148

Hello everyone,

I am trying to implement the (4 or more) RTD Temperature Measurement circuit where I want it to be at least near about ±0.6°C accurate.

I have a two-parter question related to the TIDA-00110 reference design based on ADS1248: 

  1. Why the two current sources are placed at different points of the RTD i.e. one is placed at the power line (to the RTD) at the positive side and one is placed on the sense line on the negative side, shouldn't they be placed at the same point for better accuracy considering we are using 4-wire RTD?
  2. The accuracy mentioned in the document is ±2°C whereas the accuracy graph showed later in the same document shows the accuracy is ±0.6°C max if it is ±2°C is there a way to improve it?

Thanks for the help,

Reagards,

Yash RK

  • 0
    TI__Guru**** 193139 points
    Thank you for your interest in TIDA-00110.
    This design can Measure 2-, 3-, or 4-Wire RTD Inputs and accuracy Requirements specified is for Grid Applications which is typically±2°C.
    The design is currently configured for 3 wire RTD and hence the DAC current configuration as shown in the design. The DAC current is configurable and depends on RTD type.
    The requirements are specified such that we can use either ADS1148(16-Bit) or ADS1248 for measurement.
    If you use ADS1248 (24-Bit) you should be able to achieve the required temperature accuracy and the measurement accuracy depending on the resolution of temperature you want to measure. Table8 to table 11 provides the ADC measurement accuracy.
    This design can measure 4 channels and with linearization implemented you must be able to measure temperature within ±0.6°C using this TI design.
    Please refer to TI.com for more TI designs related to RTD.