SLYS021A January   2021  – May 2022 INA228

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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 Timing Requirements (I2C)
    7. 6.7 Timing Diagram
    8. 6.8 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Versatile High Voltage Measurement Capability
      2. 7.3.2 Internal Measurement and Calculation Engine
      3. 7.3.3 Low Bias Current
      4. 7.3.4 High-Precision Delta-Sigma ADC
        1. 7.3.4.1 Low Latency Digital Filter
        2. 7.3.4.2 Flexible Conversion Times and Averaging
      5. 7.3.5 Shunt Resistor Drift Compensation
      6. 7.3.6 Integrated Precision Oscillator
      7. 7.3.7 Multi-Alert Monitoring and Fault Detection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Power-On Reset
    5. 7.5 Programming
      1. 7.5.1 I2C Serial Interface
        1. 7.5.1.1 Writing to and Reading Through the I2C Serial Interface
        2. 7.5.1.2 High-Speed I2C Mode
        3. 7.5.1.3 SMBus Alert Response
    6. 7.6 Register Maps
      1. 7.6.1 INA228 Registers
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Device Measurement Range and Resolution
      2. 8.1.2 Current , Power, Energy, and Charge Calculations
      3. 8.1.3 ADC Output Data Rate and Noise Performance
      4. 8.1.4 Input Filtering Considerations
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Select the Shunt Resistor
        2. 8.2.2.2 Configure the Device
        3. 8.2.2.3 Program the Shunt Calibration Register
        4. 8.2.2.4 Set Desired Fault Thresholds
        5. 8.2.2.5 Calculate Returned Values
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.2 Internal Measurement and Calculation Engine

The current and charge are calculated after a shunt voltage measurement, while the power and energy are calculated after a bus voltage measurement. Power and energy are calculated based on the previous current calculation and the latest bus voltage measurement. If the value loaded into the SHUNT_CAL register is zero, the power, energy and charge values will be reported as zero.

The current, voltage, and temperature values are immediate results when the number of averages is set to one as shown in Figure 7-2. However, when averaging is used, each ADC measurement is an intermediate result which is stored in the corresponding averaging registers. Following every ADC sample, the newly-calculated values for current, voltage, and temperature are appended to their corresponding averaging registers until the set number of averages is achieved. After all of the samples have been measured the average current and voltage is determined, the power is calculated and the results are loaded to the corresponding output registers where they can then be read.

The energy and charge values are accumulated for each conversion cycle. Therefore the INA228 averaging function is not applied to these.

Calculations for power, charge and energy are performed in the background and do not add to the overall conversion time.

GUID-20201116-CA0I-6SZF-DXLB-DQG91MJWDNDB-low.gifFigure 7-2 Power, Energy and Charge Calculation Scheme