SBAS924A July   2018  – November 2018 ADS1219

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Voltage, Current, and Temperature Monitoring Application
  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 I2C Timing Requirements
    7. 6.7 I2C 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 Rail-to-Rail Input Buffers and Programmable Gain Stage
      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 Offset Calibration
    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 Power-Down Mode
    5. 8.5 Programming
      1. 8.5.1 I2C Interface
        1. 8.5.1.1 I2C Address
        2. 8.5.1.2 Serial Clock (SCL) and Serial Data (SDA)
        3. 8.5.1.3 Data Ready (DRDY)
        4. 8.5.1.4 Interface Speed
        5. 8.5.1.5 Data Transfer Protocol
        6. 8.5.1.6 I2C General Call (Software Reset)
        7. 8.5.1.7 Timeout
      2. 8.5.2 Data Format
      3. 8.5.3 Commands
        1. 8.5.3.1 Command Latching
        2. 8.5.3.2 RESET (0000 011x)
        3. 8.5.3.3 START/SYNC (0000 100x)
        4. 8.5.3.4 POWERDOWN (0000 001x)
        5. 8.5.3.5 RDATA (0001 xxxx)
        6. 8.5.3.6 RREG (0010 0rxx)
        7. 8.5.3.7 WREG (0100 00xx dddd dddd)
      4. 8.5.4 Reading Data and Monitoring for New Conversion Results
    6. 8.6 Register Map
      1. 8.6.1 Configuration and Status Registers
      2. 8.6.2 Register Descriptions
        1. 8.6.2.1 Configuration Register (address = 0h) [reset = 00h]
          1. Table 10. Configuration Register Field Descriptions
        2. 8.6.2.2 Status Register (address = 1h) [reset = 00h]
          1. Table 11. Status Register Field Descriptions
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Interface Connections
      2. 9.1.2 Connecting Multiple Devices on the Same I2C Bus
      3. 9.1.3 Unused Inputs and Outputs
      4. 9.1.4 Analog Input Filtering
      5. 9.1.5 External Reference and Ratiometric Measurements
      6. 9.1.6 Establishing Proper Limits on the Absolute Input Voltage
      7. 9.1.7 Pseudo Code Example
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Voltage Monitoring
        2. 9.2.2.2 High-Side Current Measurement
        3. 9.2.2.3 Thermistor Measurement
        4. 9.2.2.4 Register Settings
      3. 9.2.3 Application Curve
  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 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

9.1.7 Pseudo Code Example

The following list shows a pseudo code sequence with the required steps to set up the device and the microcontroller that interfaces to the ADC in order to take subsequent readings from the ADS1219 in continuous conversion mode. The DRDY pin is used to indicate availability of new conversion data. The default configuration register settings are changed to gain = 4 and continuous conversion mode.


Power-up; Delay to allow power supplies to settle and power-on reset to complete; minimum of 500 µs; Configure the I2C interface of the microcontroller; Configure the microcontroller GPIO connected to the DRDY pin as a falling edge triggered interrupt input; Send the RESET command (06h) to make sure the device is properly reset after power-up; Write the respective register configuration with the WREG command (40h, 12h); As an optional sanity check, read back the configuration register with the RREG command (20h); Send the START/SYNC command (08h) to start converting in continuous conversion mode; Loop { Wait for DRDY to transition low; Send the RDATA command (10h) to read 3 bytes of conversion data; } Send the POWERDOWN command (02h) to stop conversions and put the device in power-down mode;

TI recommends running an offset calibration before performing any measurements or when changing the gain or MUX settings. The internal offset of the device can, for example, be measured by shorting the inputs to mid-supply (MUX[2:0] = 111). The microcontroller then takes multiple readings from the device with the inputs shorted and stores the average value in the microcontroller memory. When measuring the sensor signal, the microcontroller then subtracts the stored offset value from each device reading to obtain an offset compensated result; the offset can be either positive or negative in value.