ZHCSLH7C June   2020  – June 2021 INA2290 , INA290 , INA4290

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  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 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 Amplifier Input Common-Mode Range
      2. 7.3.2 Input-Signal Bandwidth
      3. 7.3.3 Low Input Bias Current
      4. 7.3.4 Low VSENSE Operation
      5. 7.3.5 Wide Fixed-Gain Output
      6. 7.3.6 Wide Supply Range
    4. 7.4 Device Functional Modes
      1. 7.4.1 Unidirectional Operation
      2. 7.4.2 High Signal Throughput
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 RSENSE and Device Gain Selection
      2. 8.1.2 Input Filtering
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Overload Recovery With Negative VSENSE
      3. 8.2.3 Application Curve
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 接收文档更新通知
    3. 11.3 支持资源
    4. 11.4 Trademarks
    5. 11.5 静电放电警告
    6. 11.6 术语表
  12. 12Mechanical, Packaging, and Orderable Information

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

8.1.1 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 1 gives the maximum value for the current-sense resistor for a given power dissipation budget:

Equation 1. GUID-20200713-CA0I-WCQ9-KM9Q-FKT41H51Q3KF-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 results from the power-supply voltage, VS, and device swing-to-rail limitations. To ensure that the current-sense signal is properly passed to the output, both positive and negative output swing limitations must be examined. Equation 2 provides the maximum values of RSENSE and GAIN to keep the device from exceeding the positive swing limitation.

Equation 2. GUID-20200713-CA0I-PPBS-PWFZ-3RHSVCJ5SJNM-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 this data sheet.

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 selecting a lower gain device is possible to avoid positive swing limitations.

The negative swing limitation places a limit on how small the sense resistor value can be for a given application. Equation 3 provides the limit on the minimum value of the sense resistor.

Equation 3. GUID-20200713-CA0I-WZZJ-L6Z7-Z55T4XDVG5B4-low.gif

where:

  • IMIN is the minimum current that flows through RSENSE.
  • GAIN is the gain of the current-sense amplifier.
  • VSN is the negative output swing of the device.

Table 8-1 shows an example of the different results obtained from using five different gain versions of the INAx290. From the table data, the highest gain device allows a smaller current-shunt resistor and decreased power dissipation in the element.

Table 8-1 RSENSE Selection and Power Dissipation
PARAMETER(1)EQUATIONRESULTS AT VS = 5 V
INAx290A1INAx290A2INAx290A3INAx290A4INAx290A5
GGain20 V/V50 V/V100 V/V200 V/V500 V/V
VSENSEIdeal differential input voltage (Ignores swing limitation and power-supply variation.)VSENSE = VOUT / G250 mV100 mV50 mV25 mV10 mV
RSENSECurrent-sense resistor valueRSENSE = VSENSE / IMAX25 mΩ10 mΩ5 mΩ2.5 mΩ1 mΩ
PSENSECurrent-sense resistor power dissipationRSENSE x IMAX22.5 W1 W0.5W0.25 W0.1 W
(1) Design example with 10-A, full-scale current with maximum output voltage set to 5 V.
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