SBOS644C February   2013  – March 2018 INA231

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      High-or Low-Side Sensing
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
    1.     Pin Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements: I2C Bus
    7. 7.7 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Basic Analog-to-Digital Converter (ADC) Functions
        1. 8.3.1.1 Power Calculation
        2. 8.3.1.2 ALERT Pin
    4. 8.4 Device Functional Modes
      1. 8.4.1 Averaging and Conversion Time Considerations
    5. 8.5 Programming
      1. 8.5.1 Configure, Measure, and Calculate Example
      2. 8.5.2 Programming the Power Measurement Engine
        1. 8.5.2.1 Calibration Register and Scaling
      3. 8.5.3 Simple Current Shunt Monitor Usage (No Programming Necessary)
      4. 8.5.4 Default INA231 Settings
      5. 8.5.5 Writing to and Reading from the INA231
        1. 8.5.5.1 Bus Overview
          1. 8.5.5.1.1 Serial Bus Address
          2. 8.5.5.1.2 Serial Interface
        2. 8.5.5.2 High-Speed I2C Mode
      6. 8.5.6 SMBus Alert Response
    6. 8.6 Register Maps
      1. Table 3. Summary of Register Set
      2. 8.6.1     Configuration Register (00h, Read/Write)
        1. Table 4. Configuration Register (00h, Read/Write) Descriptions
        2. 8.6.1.1   AVG Bit Settings [11:9]
          1. Table 5. AVG Bit Settings [11:9] Description
        3. 8.6.1.2   VBUS CT Bit Settings [8:6]
          1. Table 6. VBUS CT Bit Settings [8:6] Description
        4. 8.6.1.3   VSH CT Bit Settings [5:3]
          1. Table 7. Register Description VSH CT Bit Settings [5:3]
        5. 8.6.1.4   Mode Settings [2:0]
          1. Table 8. Mode Settings [2:0]
      3. 8.6.2     Shunt Voltage Register (01h, Read-Only)
        1. Table 9. Shunt Voltage Register (01h, Read-Only) Description
      4. 8.6.3     Bus Voltage Register (02h, Read-Only)
        1. Table 10. Bus Voltage Register (02h, Read-Only) Description
      5. 8.6.4     Power Register (03h, Read-Only)
        1. Table 11. Power Register (03h, Read-Only) Description
      6. 8.6.5     Current Register (04h, Read-Only)
        1. Table 12. Current Register (04h, Read-Only) Description
      7. 8.6.6     Calibration Register (05h, Read/Write)
        1. Table 13. Calibration Register (05h, Read/Write) Description
      8. 8.6.7     Mask/Enable Register (06h, Read/Write)
        1. Table 14. Mask/Enable Register (06h, Read/Write) Description
      9. 8.6.8     Alert Limit Register (07h, Read/Write)
        1. Table 15. Alert Limit Register (07h, Read/Write) Description
  9. Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Filtering and Input Considerations
    2. 9.2 Typical Applications
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  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

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • YFF|12
  • YFD|12
Thermal pad, mechanical data (Package|Pins)
Orderable Information

Averaging and Conversion Time Considerations

The INA231 has programmable conversion times for both the shunt voltage and bus voltage measurements. The conversion times for these measurements can be selected from as fast as 140 μs to as long as 8.244 ms. The conversion time settings, along with the programmable averaging mode, allow the INA231 to be configured to optimize the available timing requirements in a given application. For example, if a system requires that data be read every 5 ms, the INA231 can be configured with the conversion times set to 588 μs and the averaging mode set to 4. This configuration results in the data updating approximately every 4.7 ms. The INA231 can also be configured with a different conversion time setting for the shunt and bus voltage measurements. This type of approach is common in applications where the bus voltage tends to be relatively stable. This situation allows for the time spent measuring the bus voltage to be reduced relative to the shunt voltage measurement. The shunt voltage conversion time can be set to 4.156 ms with the bus voltage conversion time set to 588 μs, and the averaging mode set to 1. This configuration also results in data updating approximately every 4.7 ms.

There are trade-offs associated with the conversion time settings and the averaging mode used. The averaging feature can significantly improve the measurement accuracy by effectively filtering the signal. This approach allows the INA231 to reduce noise in the measurement that may be caused by noise coupling into the signal. A greater number of averages enables the INA231 to be more effective in reducing the noise component of the measurement.

The conversion times selected can also have an impact on the measurement accuracy; this effect can be seen in Figure 22. Multiple conversion times are shown to illustrate the impact of noise on the measurement. In order to achieve the highest accuracy measurement possible, use a combination of the longest allowable conversion times and highest number of averages, based on the timing requirements of the system.

INA231 ai_tc_noise_conversion_bos547.gifFigure 22. Noise vs Conversion Time