SBOS793G April   2017  – May 2020 INA181 , INA2181 , INA4181


  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Typical Application Circuit
  4. Revision History
  5. Device Comparison Table
  6. Pin Configuration and Functions
    1.     Pin Functions: INA181 (Single Channel)
    2.     Pin Functions: INA2181 (Dual Channel) and INA4181 (Quad Channel)
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1 High Bandwidth and Slew Rate
      2. 8.3.2 Bidirectional Current Monitoring
      3. 8.3.3 Wide Input Common-Mode Voltage Range
      4. 8.3.4 Precise Low-Side Current Sensing
      5. 8.3.5 Rail-to-Rail Output Swing
    4. 8.4 Device Functional Modes
      1. 8.4.1 Normal Mode
      2. 8.4.2 Unidirectional Mode
      3. 8.4.3 Bidirectional Mode
      4. 8.4.4 Input Differential Overload
      5. 8.4.5 Shutdown Mode
  9. Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Basic Connections
      2. 9.1.2 RSENSE and Device Gain Selection
      3. 9.1.3 Signal Filtering
      4. 9.1.4 Summing Multiple Currents
      5. 9.1.5 Detecting Leakage Currents
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
    1. 10.1 Common-Mode Transients Greater Than 26 V
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Related Links
    4. 12.4 Receiving Notification of Documentation Updates
    5. 12.5 Support Resources
    6. 12.6 Trademarks
    7. 12.7 Electrostatic Discharge Caution
    8. 12.8 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

Shutdown Mode

Although the INAx181 do not have a shutdown pin, the low power consumption of these devices allows the output of a logic gate or transistor switch to power the INAx181. This gate or switch turns on and off the INAx181 power-supply quiescent current.

However, in current shunt monitoring applications, there is also a concern for how much current is drained from the shunt circuit in shutdown conditions. Evaluating this current drain involves considering the simplified schematic of the INAx181 in shutdown mode, as shown in Figure 46.

INA181 INA2181 INA4181 ai_en_bos793.gifFigure 46. Basic Circuit to Shut Down the INA181 With a Grounded Reference

There is typically more than 500 kΩ of impedance (from the combination of 500-kΩ feedback and
input gain set resistors) from each input of the INAx181 to the OUT pin and to the REF pin. The amount of current flowing through these pins depends on the voltage at the connection. For example, if the REF pin is grounded, the calculation of the effect of the 500 kΩ impedance from the shunt to ground is straightforward. However, if the reference is powered while the INAx181 is in shutdown mode, instead of assuming 500 kΩ to ground, assume 500 kΩ to the reference voltage.

Regarding the 500-kΩ path to the output pin, the output stage of a disabled INAx181 does constitute a good path to ground. Consequently, this current is directly proportional to a shunt common-mode voltage present across a 500-kΩ resistor.

As a final note, as long as the shunt common-mode voltage is greater than VS when the device is powered up, there is an additional and well-matched 55-µA typical current that flows in each of the inputs. If less than VS, the common-mode input currents are negligible, and the only current effects are the result of the 500-kΩ resistors.