SBAU206B april   2015  – may 2023 ADS1262 , ADS1263

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1EVM Overview
    1. 1.1 ADS1263EVM Kit
    2. 1.2 ADS1263EVM Board
  5. 2Getting Started With the ADS1263EVM
  6. 3Analog Interface
    1. 3.1 Analog Input Options
      1. 3.1.1 ADS1263 Integrated Input Functions
        1. 3.1.1.1 ADC Inputs
        2. 3.1.1.2 IDAC Output
        3. 3.1.1.3 VBIAS Output
        4. 3.1.1.4 External Reference
        5. 3.1.1.5 Test DAC Output
        6. 3.1.1.6 GPIO
      2. 3.1.2 Analog Sensor Connections
        1. 3.1.2.1 Connecting a Thermocouple to J4 on the ADS1263EVM
        2. 3.1.2.2 Connecting a Thermistor to J3 on the ADS1263EVM
        3. 3.1.2.3 Using Thermistor RT1 for Thermocouple Cold-Junction Compensation
        4. 3.1.2.4 Connecting an RTD to J3 on the ADS1263EVM
          1. 3.1.2.4.1 Connecting a 2-Wire RTD
          2. 3.1.2.4.2 Connecting a 3-Wire RTD
          3. 3.1.2.4.3 Connecting a 4-Wire RTD
    2. 3.2 ADC Connections and Decoupling
    3. 3.3 Clocking
    4. 3.4 Voltage Reference
  7. 4Digital Interface
  8. 5Power Supplies
  9. 6Software Installation
  10. 7EVM Operation and GUI
    1. 7.1 Connecting the EVM Hardware
    2. 7.2 EVM GUI Global Settings for ADC Control
    3. 7.3 Time Domain Display
    4. 7.4 Frequency Domain Display
    5. 7.5 Histogram Display
    6. 7.6 Using the GUI to Control ADC2
  11. 8Bill of Materials, PCB Layout, and Schematics
    1. 8.1 Bill of Materials
    2. 8.2 PCB Layout
    3. 8.3 Schematics
  12. 9Revision History

3.1.2.4 Connecting an RTD to J3 on the ADS1263EVM

The ADS1263EVM provides the flexibility to measure multiple RTD types and configurations using differential pairs AIN0 and AIN1, AIN2 and AIN3, or AIN6 and AIN7 through terminal block J3. Each of these differential pairs has a differential filter with a cutoff frequency of 50 kHz. Additionally, each input has a common-mode filter with a cutoff frequency of 497.36 kHz. See Figure 3-1 for an overview of the ADS1263EVM analog input connections.

The ADS1263EVM also includes a placeholder for a precision reference resistor (R1) in series with the RTD. The ADS1263 integrated IDACs provide a constant current through both the RTD and R1 to establish a ratiometric reference voltage between AIN4 and AIN5 on the EVM. Any noise or drift in the IDAC occurs equally in the input and reference voltage, and therefore cancels out.

Choose resistor R1 to accommodate the RTD resistance across the entire temperature range. For example, a Pt1000 at 850°C has a typical impedance of approximately 3.9-kΩ. A 0-Ω resistor must also be installed at R2 to provide the IDAC a path to ground.

Choose the IDAC current magnitude and the total circuit impedance to make sure that the ADC IDAC compliance voltage is met. For additional information regarding ratiometric RTD measurement circuits using precision ADCs and for important specifications including compliance voltage, see the A Basic Guide to RTD Measurements application note.

The following sections detail how to connect a 2-wire, 3-wire, or 4-wire RTD to the ADS1263EVM.