SBOS728A February   2015  – March 2021 INA225-Q1

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 (1)
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 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 Selecting A Shunt Resistor
        1. 7.3.1.1 Selecting A Current-Sense Resistor Example
        2. 7.3.1.2 Optimizing Power Dissipation versus Measurement Accuracy
      2. 7.3.2 Programmable Gain Select
    4. 7.4 Device Functional Modes
      1. 7.4.1 Input Filtering
      2. 7.4.2 Shutting Down the Device
      3. 7.4.3 Using the Device with Common-Mode Transients Above 36 V
  8. 8 Applications and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Microcontroller-Configured Gain Selection
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curve
      2. 8.2.2 Unidirectional Operation
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curve
      3. 8.2.3 Bidirectional Operation
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
        3. 8.2.3.3 Application Curve
  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 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.1.2 Optimizing Power Dissipation versus Measurement Accuracy

The example shown in Table 7-1 results in a maximum current-sensing resistor value of 16 mΩ to develop the
160 mV required to achieve the 4-V full-scale output with the gain set to 25 V/V. The power dissipated across this 16-mΩ resistor at the 10-A current level is 1.6 W, which is a fairly high power dissipation for this component. Adjusting the device gain allows alternate current-sense resistor values to be selected to ease the power dissipation requirement of this component.

Changing the gain setting from 25 V/V to 100 V/V, as shown in Table 7-2, decreases the maximum differential input voltage from 160 mV down to 40 mV, thus requiring only a 4-mΩ current-sensing resistor to achieve the
4-V output at the 10-A current level. The power dissipated across this resistor at the 10-A current level is
400 mW, significantly increasing the availability of component options to select from.

The increase in gain by a factor of four reduces the power dissipation requirement of the current-sensing resistor by this same factor of four. However, with this smaller full-scale signal, the measurement uncertainty resulting from the device fixed input offset voltage increases by the same factor of four. The measurement error resulting from the device input offset voltage is approximately 0.1% at the 160-mV full-scale input signal for the 25-V/V gain setting. Increasing the gain to 100 V/V and decreasing the full-scale input signal to 40 mV increases the offset induced measurement error to 0.38%.

Table 7-2 Accuracy and RSENSE Power Dissipation vs. Gain Setting
PARAMETER EQUATION RESULT
IMAX Full-scale current 10 A
VOUT Full-scale output voltage 4 V
Gain Gain selected 100 V/V
VDIFF Ideal maximum differential input voltage VDiff = VOUT / Gain 40 mV
RSENSE Current-sense resistor value RSENSE = VDiff / IMAX 4 mΩ
PRSENSE Current-sense resistor power dissipation RSENSE x IMAX2 0.4 W
VOS Error Offset voltage error (VOS / VDIFF ) x 100 0.375%