SLYS025A January   2021  – May 2022 INA238

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 Power Calculation
      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 Integrated Precision Oscillator
      6. 7.3.6 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 INA238 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 and Power 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

8.2.2.5 Calculate Returned Values

Parametric values are calculated by multiplying the returned value by the LSB value. Table 8-4 below shows the returned values for this application example assuming the design requirements shown in Table 8-3.

Table 8-4 Calculating Returned Values
PARAMETER Returned Value LSB Value Calculated Value
Shunt voltage (V) 19440d 5 µV/LSB 0.0972 V
Current (A) 19660d 10 A/215 = 305.176 µA/LSB 5.9997 A
Bus voltage (V) 15360d 3.125 mV/LSB 48 V
Power (W) 4718604d Current LSB x 0.2 = 61.035156 µW/LSB 288 W
Temperature (°C) 200d 125 m°C/LSB 25°C

Shunt Voltage, Current, Bus Voltage (positive only), and Temperature return values in two's complement format. In two's complement format a negative value in binary is represented by having a 1 in the most significant bit of the returned value. These values can be converted to decimal by first inverting all the bits and adding 1 to obtain the unsigned binary value. This value should then be converted to decimal with the negative sign applied. For example, assume a shunt voltage reading returns 1011 0100 0001 0000. This is a negative value due to the MSB having a value of one. Inverting the bits and adding one results in 0100 1011 1111 0000 (19440d) which from the shunt voltage example in Table 8-4 correlates to a voltage of 97.2 mV. Since the returned value was negative the measured shunt voltage value is -97.2 mV.