SBAS752B May   2017  – October 2018 ADS122U04

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      K-Type Thermocouple Measurement
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 UART Timing Requirements
    7. 6.7 UART Switching Characteristics
    8. 6.8 Typical Characteristics
  7. 7 Parameter Measurement Information
    1. 7.1 Noise Performance
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Multiplexer
      2. 8.3.2  Low-Noise Programmable Gain Stage
        1. 8.3.2.1 PGA Input Voltage Requirements
        2. 8.3.2.2 Bypassing the PGA
      3. 8.3.3  Voltage Reference
      4. 8.3.4  Modulator and Internal Oscillator
      5. 8.3.5  Digital Filter
      6. 8.3.6  Conversion Times
      7. 8.3.7  Excitation Current Sources
      8. 8.3.8  Sensor Detection
      9. 8.3.9  System Monitor
      10. 8.3.10 Temperature Sensor
        1. 8.3.10.1 Converting From Temperature to Digital Codes
          1. 8.3.10.1.1 For Positive Temperatures (For Example, 50°C):
          2. 8.3.10.1.2 For Negative Temperatures (For Example, –25°C):
        2. 8.3.10.2 Converting From Digital Codes to Temperature
      11. 8.3.11 Offset Calibration
      12. 8.3.12 Conversion Data Counter
      13. 8.3.13 Data Integrity
      14. 8.3.14 General-Purpose Digital Inputs/Outputs
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-Up and Reset
        1. 8.4.1.1 Power-On Reset
        2. 8.4.1.2 RESET Pin
        3. 8.4.1.3 Reset by Command
      2. 8.4.2 Conversion Modes
        1. 8.4.2.1 Single-Shot Conversion Mode
        2. 8.4.2.2 Continuous Conversion Mode
      3. 8.4.3 Operating Modes
        1. 8.4.3.1 Normal Mode
        2. 8.4.3.2 Turbo Mode
        3. 8.4.3.3 Power-Down Mode
    5. 8.5 Programming
      1. 8.5.1 UART Interface
        1. 8.5.1.1 Receive (RX)
        2. 8.5.1.2 Transmit (TX)
        3. 8.5.1.3 Data Ready (DRDY)
        4. 8.5.1.4 Protocol
        5. 8.5.1.5 Timeout
      2. 8.5.2 Data Format
      3. 8.5.3 Commands
        1. 8.5.3.1 RESET (0000 011x)
        2. 8.5.3.2 START/SYNC (0000 100x)
        3. 8.5.3.3 POWERDOWN (0000 001x)
        4. 8.5.3.4 RDATA (0001 xxxx)
        5. 8.5.3.5 RREG (0010 rrrx)
        6. 8.5.3.6 WREG (0100 rrrx dddd dddd)
        7. 8.5.3.7 Command Latching
      4. 8.5.4 Reading Data
        1. 8.5.4.1 Manual Data Read Mode
        2. 8.5.4.2 Automatic Data Read Mode
      5. 8.5.5 Data Integrity
    6. 8.6 Register Map
      1. 8.6.1 Configuration Registers
      2. 8.6.2 Register Descriptions
        1. 8.6.2.1 Configuration Register 0 (address = 00h) [reset = 00h]
          1. Table 18. Configuration Register 0 Field Descriptions
        2. 8.6.2.2 Configuration Register 1 (address = 01h) [reset = 00h]
          1. Table 19. Configuration Register 1 Field Descriptions
        3. 8.6.2.3 Configuration Register 2 (address = 02h) [reset = 00h]
          1. Table 21. Configuration Register 2 Field Descriptions
        4. 8.6.2.4 Configuration Register 3 (address = 03h) [reset = 00h]
          1. Table 22. Configuration Register 3 Field Descriptions
        5. 8.6.2.5 Configuration Register 4 (address = 04h) [reset = 00h]
          1. Table 23. Configuration Register 4 Field Descriptions
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Interface Connections
      2. 9.1.2 Analog Input Filtering
      3. 9.1.3 External Reference and Ratiometric Measurements
      4. 9.1.4 Establishing Proper Limits on the Absolute Input Voltage
      5. 9.1.5 Unused Inputs and Outputs
      6. 9.1.6 Pseudo Code Example
    2. 9.2 Typical Applications
      1. 9.2.1 K-Type Thermocouple Measurement (–200°C to +1250°C)
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 3-Wire RTD Measurement (–200°C to +850°C)
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Design Variations for 2-Wire and 4-Wire RTD Measurements
        3. 9.2.2.3 Application Curves
      3. 9.2.3 Resistive Bridge Measurement
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
  10. 10Power Supply Recommendations
    1. 10.1 Power-Supply Sequencing
    2. 10.2 Power-Supply Decoupling
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

8.5.3 Commands

As Table 15 shows, the device offers six different commands to control device operation. Four commands are stand-alone instructions (RESET, START/SYNC, POWERDOWN, and RDATA). The commands to read (RREG) and write (WREG) configuration register data from and to the device require additional information as part of the instruction. For clarity, Table 15 shows the command bits MSB first, but data are always transmitted byte-wise LSB first on the ADS122U04.

Table 15. Command Definitions

COMMAND DESCRIPTION COMMAND BYTE(1)
RESET Reset the device 0000 011x
START/SYNC Start or restart conversions 0000 100x
POWERDOWN Enter power-down mode 0000 001x
RDATA Read data by command 0001 xxxx
RREG Read register at address rrr 0010 rrrx
WREG Write register at address rrr 0100 rrrx
(1) Operands: rrr = register address (000 to 100), x = don't care.