JAJSGY6C february   2019  – august 2021 INA191 , INA2191

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  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 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 Precision Current Measurement
      2. 7.3.2 Low Input Bias Current
      3. 7.3.3 Low Quiescent Current With Output Enable
      4. 7.3.4 Bidirectional Current Monitoring (INA2191 Only)
      5. 7.3.5 High-Side and Low-Side Current Sensing
      6. 7.3.6 High Common-Mode Rejection
      7. 7.3.7 Rail-to-Rail Output Swing
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation
      2. 7.4.2 Unidirectional Mode
      3. 7.4.3 Bidirectional Mode (INA2191 Only)
      4. 7.4.4 Input Differential Overload
      5. 7.4.5 Shutdown
  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 Conditioning
      4. 8.1.4 Common-Mode Voltage Transients
    2. 8.2 Typical Application
      1. 8.2.1 Microamp Current Measurement
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curve
  10. 9 Power Supply Recommendations
  11. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
  12. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 ドキュメントの更新通知を受け取る方法
    3. 11.3 サポート・リソース
    4. 11.4 Trademarks
    5. 11.5 静電気放電に関する注意事項
    6. 11.6 用語集
  13. 12Mechanical, Packaging, and Orderable Information

パッケージ・オプション

デバイスごとのパッケージ図は、PDF版データシートをご参照ください。

メカニカル・データ（パッケージ｜ピン）
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サーマルパッド・メカニカル・データ
発注情報

8.1.2 RSENSE and Device Gain Selection

The accuracy of any current-sense amplifier is maximized by choosing the current-sense resistor to be as large as possible. A large sense resistor maximizes the differential input signal for a given amount of current flow and reduces the error contribution of the offset voltage. However, there are practical limits as to how large the current-sense resistor can be in a given application because of the resistor size and maximum allowable power dissipation. Equation 2 gives the maximum value for the current-sense resistor for a given power dissipation budget:

Equation 2. GUID-D22B6BBC-6DF1-468C-A29D-92424755A1B3-low.gif

where:

  • PDMAX is the maximum allowable power dissipation in RSENSE.
  • IMAX is the maximum current that flows through RSENSE.

An additional limitation on the size of the current-sense resistor and device gain is due to the power-supply voltage, VS, and device swing-to-rail limitations. In order to make sure that the current-sense signal is properly passed to the output, both positive and negative output swing limitations must be examined. Equation 3 provides the maximum values of RSENSE and GAIN to keep the device from hitting the positive swing limitation.

Equation 3. GUID-2AF5B774-086E-4959-B056-4B384358A4FA-low.gif

where:

  • IMAX is the maximum current that flows through RSENSE.
  • GAIN is the gain of the current-sense amplifier.
  • VSP is the positive output swing as specified in the data sheet.
  • VREF is the reference input. This is node is internally grounded for the INA191 and a value of 0 V should be used for that device.

To avoid positive output swing limitations when selecting the value of RSENSE, there is always a trade-off between the value of the sense resistor and the gain of the device under consideration. If the sense resistor selected for the maximum power dissipation is too large, then it is possible to select a lower-gain device in order to avoid positive swing limitations.

The zero current output voltage places a limit on how small of a sense resistor can be used in a given application. Equation 4 provides the limit on the minimum size of the sense resistor.

Equation 4. GUID-20210121-CA0I-MRSL-HBCF-JD5WFGWSWSVJ-low.gif

where:

  • IMIN is the minimum current flows through RSENSE.
  • GAIN is the gain of the current-sense amplifier.
  • VZL is the zero current output voltage of the device (see the Section 7.3.7 section for more information).
  • VREF is the reference input. This node is internally grounded for the INA191 and a value of 0 V should be used for that device.