SBOSA81D may   2021  – august 2023 INA236

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Integrated Analog-to-Digital Convertor (ADC)
      2. 7.3.2 Power Calculation
      3. 7.3.3 Low Bias Current
      4. 7.3.4 Low Voltage Supply and Wide Common-Mode Voltage Range
      5. 7.3.5 ALERT Pin
    4. 7.4 Device Functional Modes
      1. 7.4.1 Continuous Verses Triggered Operation
      2. 7.4.2 Device Shutdown
      3. 7.4.3 Power-On Reset
      4. 7.4.4 Averaging and Conversion Time Considerations
    5. 7.5 Programming
      1. 7.5.1 I2C Serial Interface
      2. 7.5.2 Writing to and Reading Through the I2C Serial Interface
      3. 7.5.3 High-Speed I2C Mode
      4. 7.5.4 General Call Reset
      5. 7.5.5 General Call Start Byte
      6. 7.5.6 SMBus Alert Response
    6. 7.6 Register Maps
      1. 7.6.1 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 Register
        4. 8.2.2.4 Set Desired Fault Thresholds
        5. 8.2.2.5 Calculate Returned Values
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Development Support
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • DDF|8
  • YBJ|8
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.1.2 Current and Power Calculations

For the INA236 to report current values in Amperes, a constant conversion value must be written in the calibration register that is dependent on the selected CURRENT_LSB and the shunt resistance used in the application. 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 it directly defines the maximum resolution of the CURRENT register. While the smallest CURRENT_LSB value yields highest resolution, it is common to select 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. GUID-20210417-CA0I-NJ8W-N6GX-R756PJTF8ZP9-low.gif

where

  • 0.00512 is an internal fixed value used to ensure 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. GUID-20210417-CA0I-1WFF-GN29-HMPWM7FWZNTR-low.svg

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

After programming the SHUNT_CAL register 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. GUID-DF56AF98-F57E-41EB-89A1-F6723F758787-low.gif

where

  • CURRENT is the value read from the CURRENT register

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

 

Equation 4. GUID-20210417-CA0I-P1N8-XRP6-VCTG68R3W70F-low.gif

where

  • POWER is the value read from the POWER register.
  • CURRENT_LSB is selected value for the lsb size of the current calculation used in Equation 1.

 

Refer to Detailed Design Procedure for a design example using these equations.