SLYS018F April   2018  – October 2024 INA181-Q1 , INA2181-Q1 , INA4181-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  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 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 High Bandwidth and Slew Rate
      2. 7.3.2 Bidirectional Current Monitoring
      3. 7.3.3 Wide Input Common-Mode Voltage Range
      4. 7.3.4 Precise Low-Side Current Sensing
      5. 7.3.5 Rail-to-Rail Output Swing
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Mode
      2. 7.4.2 Unidirectional Mode
      3. 7.4.3 Bidirectional Mode
      4. 7.4.4 Input Differential Overload
      5. 7.4.5 Shutdown Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Basic Connections
      2. 8.1.2 RSENSE and Device Gain Selection
      3. 8.1.3 Signal Filtering
      4. 8.1.4 Summing Multiple Currents
      5. 8.1.5 Detecting Leakage Currents
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 Common-Mode Transients Greater Than 26 V
    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. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.4.3 Bidirectional Mode

The INAx181-Q1 are bidirectional, current-sense amplifiers capable of measuring currents through a resistive shunt in two directions. This bidirectional monitoring is common in applications that include charging and discharging operations where the current flowing through the resistor can change directions.

INA181-Q1 INA2181-Q1 INA4181-Q1 Bidirectional ApplicationFigure 7-7 Bidirectional Application

The ability to measure this current flowing in both directions is enabled by applying a voltage to the REF pin, as shown in Figure 7-7. The voltage applied to REF (VREF) sets the output state that corresponds to the zero-input level state. The output then responds by increasing above VREF for positive differential signals (relative to the IN– pin) and responds by decreasing below VREF for negative differential signals. This reference voltage applied to the REF pin can be set anywhere between 0 V to VS. For bidirectional applications, VREF is typically set at mid-scale for equal signal range in both current directions. In some cases, however, VREF is set at a voltage other than mid-scale when the bidirectional current and corresponding output signal do not need to be symmetrical.