SBASB61 August   2026 ADS114S18 , ADS124S18

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements
    7. 5.7 Switching Characteristics
    8. 5.8 Timing Diagrams
    9. 5.9 Typical Characteristics
  7. 6 Parameter Measurement Information
    1. 6.1 Noise Performance
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Analog Inputs and Multiplexer
      2. 7.3.2  Programmable Gain Amplifier (PGA)
      3. 7.3.3  Voltage Reference
        1. 7.3.3.1 Internal Reference
        2. 7.3.3.2 External Reference
        3. 7.3.3.3 Reference Buffers
      4. 7.3.4  Power-Scalable Speed Modes
      5. 7.3.5  Clock Source
      6. 7.3.6  Delta-Sigma Modulator
      7. 7.3.7  Digital Filter
        1. 7.3.7.1 Sinc3 and Sinc4 Filters
        2. 7.3.7.2 Sinc4 + Sinc1 Filter
        3. 7.3.7.3 FIR Filter
        4. 7.3.7.4 50Hz and 60Hz Line Cycle Rejection
        5. 7.3.7.5 Digital Filter Latency
        6. 7.3.7.6 Global-Chop Mode
      8. 7.3.8  Excitation Current Sources (IDACs)
      9. 7.3.9  Burn-Out Current Sources (BOCS)
      10. 7.3.10 Bias Voltage Generator (VBIAS)
      11. 7.3.11 General Purpose IOs (GPIOs)
        1. 7.3.11.1 ALERT Output
        2. 7.3.11.2 FAULT Output
      12. 7.3.12 Offset and Gain Calibration Coefficients
      13. 7.3.13 Digital Comparator
      14. 7.3.14 System Monitors
        1. 7.3.14.1 Internal Short (Offset Calibration)
        2. 7.3.14.2 Internal Temperature Sensor
        3. 7.3.14.3 External Reference Voltage Readback
        4. 7.3.14.4 Power-Supply Readback
      15. 7.3.15 Monitors and Status Flags
        1. 7.3.15.1 Reset (RESETn flag)
        2. 7.3.15.2 AVDD Undervoltage Monitor (AVDD_UVn flag)
        3. 7.3.15.3 Reference Undervoltage Monitor (REF_UVn flag)
        4. 7.3.15.4 SPI CRC Fault (SPI_CRC_FAULTn flag)
        5. 7.3.15.5 Register Map CRC Fault (REG_MAP_CRC_FAULTn flag)
        6. 7.3.15.6 Internal Memory Fault (MEM_FAULTn flag)
        7. 7.3.15.7 Register Write Fault (REG_WRITE_FAULTn flag)
        8. 7.3.15.8 Digital Comparator Alert (COMP_ALERTn flag)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Power-up and Reset
        1. 7.4.1.1 Power-On Reset (POR)
        2. 7.4.1.2 RESET Pin
        3. 7.4.1.3 Reset by Register Write
        4. 7.4.1.4 Reset by SPI Input Pattern
      2. 7.4.2 Operating Modes
        1. 7.4.2.1 Idle and Standby Mode
        2. 7.4.2.2 Power-Down Mode
        3. 7.4.2.3 Sequencer Mode
          1. 7.4.2.3.1 Configuring the Sequencer
          2. 7.4.2.3.2 Starting and Stopping the Sequencer (START/STOP bits and START pin)
          3. 7.4.2.3.3 Sequencer Status Bits
    5. 7.5 Programming
      1. 7.5.1  Serial Interface (SPI)
      2. 7.5.2  Serial Interface Signals
        1. 7.5.2.1 Chip Select (CS)
        2. 7.5.2.2 Serial Clock (SCLK)
        3. 7.5.2.3 Serial Data Input (SDI)
        4. 7.5.2.4 Serial Data Output/Data Ready (SDO/DRDY)
        5. 7.5.2.5 Data Ready (DRDY) Pin
      3. 7.5.3  Serial Interface Communication Structure
        1. 7.5.3.1 SPI Frame
        2. 7.5.3.2 STATUS Header
        3. 7.5.3.3 SPI CRC
      4. 7.5.4  Device Commands
        1. 7.5.4.1 No Operation (Read Conversion Data)
        2. 7.5.4.2 Read Register Command
        3. 7.5.4.3 Write Register Command
      5. 7.5.5  Continuous-Read Mode
        1. 7.5.5.1 Read Registers in Continuous-Read Mode
      6. 7.5.6  Daisy-Chain Operation
      7. 7.5.7  3-Wire SPI Mode
        1. 7.5.7.1 3-Wire SPI Mode Frame Re-Alignment
      8. 7.5.8  Monitoring for New Conversion Data
        1. 7.5.8.1 DRDY Pin or SDO/DRDY Pin Monitoring
        2. 7.5.8.2 Reading DRDY Bit and Conversion Counter
        3. 7.5.8.3 Clock Counting
      9. 7.5.9  DRDY Pin Behavior
      10. 7.5.10 Register Map CRC
      11. 7.5.11 Conversion Data Format
  9. 8 Register Map
    1. 8.1 Status and General Configuration Page Registers
    2. 8.2 Step Configuration Page Registers
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Serial Interface Connections
      2. 9.1.2 Unused Inputs and Outputs
      3. 9.1.3 Interfacing With Multiple Devices
      4. 9.1.4 Device Initialization and Starting the Sequencer
      5. 9.1.5 Sequencer Configuration Strategy Example
    2. 9.2 Typical Applications
      1. 9.2.1 Software-Configurable RTD Measurement Input
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Performance Plots
        4. 9.2.1.4 Design Variant – 3-Wire RTD Measurement With Automatic Lead-Wire Compensation Using Two IDACs
      2. 9.2.2 Thermocouple Measurement With Cold-Junction Compensation Using a 2-wire RTD
      3. 9.2.3 Resistive Bridge Sensor Measurement With Temperature Compensation
      4. 9.2.4 Autonomous Power Supply Monitoring
        1. 9.2.4.1 Design Requirements
        2. 9.2.4.2 Detailed Design Procedure
    3. 9.3 Power Supply Recommendations
      1. 9.3.1 Power Supplies
      2. 9.3.2 Power-Supply Sequencing
      3. 9.3.3 Power-Supply Decoupling
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

7.3.3.3 Reference Buffers

The devices provide two individually selectable reference input buffers to lower the reference input current. Use the STEPx_REFP_BUF_EN and STEPx_REFN_BUF_EN bits to enable or disable the positive and negative reference buffers respectively.

Disable the negative reference buffer when the selected external negative reference input (REFNx) is at AVSS. Disable the positive reference buffer when the selected external positive reference input (REFPx) is at AVDD. Disable both reference buffers when either the internal voltage reference or the analog supply is selected as the reference source.

The reference buffers remain active in idle mode, but turn off in standby and power-down mode.