JAJSOF5 May   2024 INA4235

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements (I2C)
    7. 5.7 Timing Diagram
    8. 5.8 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Integrated Analog-to-Digital Converter (ADC)
      2. 6.3.2 Internal Measurement and Calculation Engine
      3. 6.3.3 Low Bias Current
      4. 6.3.4 Low Voltage Supply and Wide Common-Mode Voltage Range
      5. 6.3.5 ALERT Pin
    4. 6.4 Device Functional Modes
      1. 6.4.1 Continuous Versus Triggered Operation
      2. 6.4.2 Device Low Power Modes
      3. 6.4.3 Power-On Reset
      4. 6.4.4 Averaging and Conversion Time Considerations
    5. 6.5 Programming
      1. 6.5.1 I2C Serial Interface
      2. 6.5.2 Writing to and Reading Through the I2C Serial Interface
      3. 6.5.3 High-Speed I2C Mode
      4. 6.5.4 General Call Reset
      5. 6.5.5 SMBus Alert Response
  8. 7 Register Maps
    1. 7.1 Device Registers
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Device Measurement Range and Resolution
      2. 8.1.2 Current and Power Calculations
      3. 8.1.3 ADC Output Data Rate and Noise Performance
      4. 8.1.4 Filtering and Input 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 Registers
        4. 8.2.2.4 Set Desired Fault Thresholds
        5. 8.2.2.5 Calculate Returned Values
      3. 8.2.3 Application Curves
  10. 9 Power Supply Recommendations
  11. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 ドキュメントの更新通知を受け取る方法
    4. 11.4 サポート・リソース
    5. 11.5 Trademarks
    6. 11.6 静電気放電に関する注意事項
    7. 11.7 用語集
  13. 12Revision History
  14. 13Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

8.1.2 Current and Power Calculations

For the INA4235 to report current values in Amperes, a constant conversion value must be written in each of the calibration registers that is dependent on the selected CURRENT_LSB and the shunt resistance used in the application for each channel. The value of the calibration register is calculated based on Equation 1. The term CURRENT_LSB is the chosen LSB step size for the CURRENT register where the current is stored. Equation 2 shows the minimum value of CURRENT_LSB is based on the maximum expected current, and the equation directly defines the maximum resolution of the CURRENT register. While the smallest CURRENT_LSB value yields highest resolution, this value is common for selecting a higher round-number (no higher than 8x) value for the CURRENT_LSB to simplify the conversion of the CURRENT.

The RSHUNT term is the resistance value of the external shunt used to develop the differential voltage across the IN+ and IN– pins. Use Equation 1 for ADCRANGE = 0. For ADCRANGE = 1, the value of SHUNT_CAL must be divided by 4.

Equation 1. INA4235

where

  • 0.00512 is an internal fixed value used to verify that scaling is maintained properly.
  • CURRENT_LSB is a selected value for the current step size in amperes. Must be greater than or equal to CURRENT_LSB (minimum), but less than 8 x CURRENT_LSB(minimum) to reduce resolution loss.
  • The value of SHUNT_CAL must be divided by 4 for ADCRANGE = 1.
 
Equation 2. INA4235

Note that the current is calculated following a shunt voltage measurement based on the value set in the SHUNT_CAL field. If the value loaded into the SHUNT_CAL field is zero, the current value reported through the CURRENT register is also zero.

After programming the SHUNT_CAL field with the calculated value, the measured current in Amperes can be read from the CURRENT register. Use Equation 3 to calculate the final value scaled by the CURRENT_LSB:

Equation 3. INA4235

where

  • CURRENT is the value read from the CURRENT register

The power value can be read from the POWER register as an unsigned 16-bit value. Use Equation 4 to convert the power to Watts:

 

Equation 4. INA4235

where

  • POWER is the value read from the POWER register.
  • CURRENT_LSB is chosen lsb size for the selected channel.

The energy values can be read from the each ENERGY register as a 32-bit unsigned value. Use Equation 5 to convert the energy to Joules:

 

Equation 5. INA4235

where

  • ENERGY is the value read from the each ENERGY register.
  • CURRENT_LSB is chosen lsb size for the selected channel.