SBAU378A September   2021  – January 2022 ADS1148 , ADS1248

 

  1.   Trademarks
  2. 1Introduction
  3. 2Getting Started With the ADS1x48EVM
  4. 3ADS1x48EVM Overview
    1. 3.1 Analog and Digital Power Supplies
    2. 3.2 Voltage Reference Options
    3. 3.3 Clock Options
    4. 3.4 Digital Interface
    5. 3.5 Analog Input Connections
      1. 3.5.1 Connecting a Thermocouple to J5 on the ADS1x48EVM
      2. 3.5.2 Connecting a Thermistor to J5 on the ADS1x48EVM
        1. 3.5.2.1 Using Thermistor RT1 for Thermocouple Cold Junction Compensation
      3. 3.5.3 Connecting an RTD to J6 on the ADS1x48EVM
        1. 3.5.3.1 Connecting a 2-Wire RTD Using a Low-Side RREF to J6 on the ADS1x48EVM
        2. 3.5.3.2 Connecting a 2-Wire RTD Using a High-Side RREF to J6 on the ADS1x48EVM
        3. 3.5.3.3 Connecting a 3-Wire RTD Using One IDAC and a Low-Side RREF to J6 on the ADS1x48EVM
        4. 3.5.3.4 Connecting a 3-Wire RTD Using One IDAC and a High-Side RREF to J6 on the ADS1x48EVM
        5. 3.5.3.5 Connecting a 3-Wire RTD Using Two IDACs and a Low-Side RREF to J6 on the ADS1x48EVM
        6. 3.5.3.6 Connecting a 3-Wire RTD Using Two IDACs and a High-Side RREF to J6 on the ADS1x48EVM
        7. 3.5.3.7 Connecting a 4-Wire RTD Using a Low-Side RREF to J6 on the ADS1x48EVM
        8. 3.5.3.8 Connecting a 4-Wire RTD Using a High-Side RREF to J6 on the ADS1x48EVM
        9. 3.5.3.9 Summary of ADS1x48EVM RTD Configuration Settings
      4. 3.5.4 Connecting a General-Purpose Input to J5 on the ADS1x48EVM
  5. 4ADS1x48EVM GUI
    1. 4.1 Home
      1. 4.1.1 Menu Bar
        1. 4.1.1.1 File Menu
        2. 4.1.1.2 Options Menu
        3. 4.1.1.3 Tools Menu
        4. 4.1.1.4 Help Menu
    2. 4.2 Data Capture
      1. 4.2.1 Time Domain and Histogram Statistics
      2. 4.2.2 Time Domain Plot
      3. 4.2.3 Histogram Plot
      4. 4.2.4 FFT Statistics and Plot
    3. 4.3 Register Map
      1. 4.3.1 Register Read and Write Options
        1. 4.3.1.1 Read Register Options
        2. 4.3.1.2 Write Register Options
  6. 5Bill of Materials, Printed Circuit Board Layout, and Schematic
    1. 5.1 Bill of Materials
    2. 5.2 Printed Circuit Board Layout
    3. 5.3 Schematic
  7. 6Revision History

3.2 Voltage Reference Options

The ADS1x48 is a highly flexible ADC that can accept multiple voltage reference (VREF) options. First, the ADS1x48 integrates a low-noise, 2.048-V reference to help reduce overall component count. Moreover, this internal VREF voltage is supplied externally via the ADS1x48 REFOUT pin and is available on terminal block J5. The ADS1x48 also has two sets of differential VREF inputs defined as REFP0, REFN0 and REFP1, REFN1. All of these options are selected via the MUX1 register in the ADS1x48.

The ADS1x48EVM supports four different VREF options to offer maximum flexibility. Table 3-1 details these four options. Figure 3-3 shows the location of each VREF option (highlighted in yellow) as well as each VREF test point (highlighted in red).

Table 3-1 Summary of ADS1x48EVM VREF Options
VREF ModeVREF Input ChannelVoltageLocationTest PointComment
Internal—2.048 VU3Output on J5 (REFOUT)—
ExternalREF5025REFP0, REFN02.5 VU2Output on J5 (REF5025)—
RatiometricREFP1, REFN1VariableR11REFP1, REFN1Used for RTD measurements
User-providedREFP1, REFN1VariableJ6 (REFP1, REFN1)REFP1, REFN1Remove R11
GUID-20210706-CA0I-5RWM-1WGC-Z3RVWGHWS19M-low.pngFigure 3-3 ADS1x48EVM VREF Options (Yellow) and Test Points (Red)