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

8.3.3 Voltage Reference

The device offers an integrated, low-drift, 2.048-V reference. For applications that require a different reference voltage value or a ratiometric measurement approach, the device offers a differential reference input pair (REFP and REFN).

The reference source is selected by the VREF bit in the configuration register. By default, the internal reference is selected. The internal voltage reference requires less than 25 µs to fully settle after power-up, when coming out of power-down mode, or when switching from the external reference source to the internal reference.

The differential reference input allows freedom in the reference common-mode voltage. The reference inputs are internally buffered to increase input impedance. Therefore, additional reference buffers are usually not required when using an external reference. When used in ratiometric applications, the reference inputs do not load the external circuitry; however, the analog supply current increases when using an external reference because the reference buffers are enabled.

In most cases the conversion result is directly proportional to the stability of the reference source. Any noise and drift of the voltage reference is reflected in the conversion result.