SBASAI9 December   2025 ADS112S14 , ADS122S14

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  Clock Source
      5. 7.3.5  Delta-Sigma Modulator
      6. 7.3.6  Digital Filter
        1. 7.3.6.1 Sinc4 and Sinc4 + Sinc1 Filter
        2. 7.3.6.2 FIR Filter
        3. 7.3.6.3 Digital Filter Latency
        4. 7.3.6.4 Global-Chop Mode
      7. 7.3.7  Excitation Current Sources (IDACs)
      8. 7.3.8  Burn-Out Current Sources (BOCS)
      9. 7.3.9  General Purpose IOs (GPIOs)
        1. 7.3.9.1 FAULT Output
        2. 7.3.9.2 DRDY Output
      10. 7.3.10 System Monitors
        1. 7.3.10.1 Internal Short (Offset Calibration)
        2. 7.3.10.2 Internal Temperature Sensor
        3. 7.3.10.3 External Reference Voltage Readback
        4. 7.3.10.4 Power-Supply Readback
      11. 7.3.11 Monitors and Status Flags
        1. 7.3.11.1 Reset (RESETn flag)
        2. 7.3.11.2 AVDD Undervoltage Monitor (AVDD_UVn flag)
        3. 7.3.11.3 Reference Undervoltage Monitor (REV_UVn flag)
        4. 7.3.11.4 SPI CRC Fault (SPI_CRC_FAULTn flag)
        5. 7.3.11.5 Register Map CRC Fault (REG_MAP_CRC_FAULTn flag)
        6. 7.3.11.6 Internal Memory Fault (MEM_FAULTn flag)
        7. 7.3.11.7 Register Write Fault (REG_WRITE_FAULTn flag)
        8. 7.3.11.8 DRDY Indicator (DRDY bit)
        9. 7.3.11.9 Conversion Counter (CONV_COUNT[3:0])
    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 by Register Write
        3. 7.4.1.3 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 Power-Scalable Conversion Modes
          1. 7.4.2.3.1 Continuous-Conversion Mode
          2. 7.4.2.3.2 Single-shot Conversion Mode
    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 Conversion Data Format
      11. 7.5.11 Register Map CRC
  9. 8 Registers
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Serial Interface Connections
      2. 9.1.2 Interfacing with Multiple Devices
      3. 9.1.3 Unused Inputs and Outputs
      4. 9.1.4 Device Initialization
    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
    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 Documentation Support
      1. 10.1.1 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

7.5.4.3 Write Register Command

Use the write register command to write register data. The write register operation is performed in a single frame. The first byte of the command is the base value (80h) added to the 4-bit register address. The second byte of the command is the register data.

Writing to registers outside the valid address range is ignored and the REG_WRITE_FAULTn bit is set to 0b to indicate an error.

Figure 7-25 shows an example of a register write operation for the 24-bit device with the STATUS header and CRC disabled. A shortened 16-bit frame can be used to increase throughput if a series of registers need to be configured without reading out conversion data at the same time. Shortened SPI frames cannot be used in 3-wire SPI mode or when operating the device in a daisy-chain.

ADS112S14 ADS122S14 Write Register Data (24-Bit Device, STATUS Header and CRC Disabled)
A. Previous state of SDO/DRDY before the first SCLK.
B. Data are either the conversion data, or if the read register command was sent in a prior frame, the data field is register data byte + address indication byte + 00h padding.
Figure 7-25 Write Register Data (24-Bit Device, STATUS Header and CRC Disabled)

Figure 7-26 shows an example of a write register operation for the 24-bit device with the STATUS header and CRC enabled. Full-duplex operation is also illustrated to show simultaneous input of a command and output of conversion data. The input frame is prefixed with three don't care bytes to match the output frame so all conversion data bytes are transmitted. A shortened 24-bit frame can be used to increase throughput if a series of registers need to be configured without reading out conversion data at the same time.

Verify successful register write operations by either reading back the register data, or by checking the SPI_CRC_FAULTn bit for input CRC errors. If an SPI CRC input error occurred, the SPI_CRC_FAULTn flag reads 0b in the following frame and the write operation is ignored.

ADS112S14 ADS122S14 Write Register Data (24-Bit Device, STATUS Header and CRC Enabled)
A. Optional CRC byte. If CRC is disabled, the frame shortens by one byte.
B. Optional STATUS header. If STATUS is disabled, the frame shortens by two bytes.
C. The data field is either conversion data, or if the read register command was sent in the prior frame, register data byte + address indication byte + 00h padding.
D. Previous state of SDO/DRDY before the first SCLK.
Figure 7-26 Write Register Data (24-Bit Device, STATUS Header and CRC Enabled)

Writing to the following registers (even the same value) stops any ongoing conversion, resets the digital filter and restarts conversions using the updated device configurations:

  • DEVICE_CFG (address 05h)
  • DATA_RATE_CFG (address 06h)
  • MUX_CFG (address 07h)
  • GAIN_CFG (address 08h)
  • REFERENCE_CFG (address 09h)
  • DIGITAL_CFG (address 0Ah)

This device behavior does for example help when multiplexing through multiple channels with the smallest amount of communication overhead. For that purpose, operate the device in continuous-conversion mode. Start conversions on the first measurement channel using the START bit. After the conversion completes, write a new multiplexer configuration to the MUX_CFG register to select the second channel for measurement. While writing the MUX_CFG register, read the conversion data of the first measurement channel at the same time. The device starts converting on the second measurement channel after the write register command is latched by the device.

When the device is in standby or idle mode, then writing to the above mentioned registers does not start conversions.