ZHCSCM7E July   2018  – February 2022 REF2025 , REF2030 , REF2033 , REF2041

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 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. 8 Parameter Measurement Information
    1. 8.1 Solder Heat Shift
    2. 8.2 Long-Term Stability
    3. 8.3 Thermal Hysteresis
    4. 8.4 Noise Performance
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 VREF and VBIAS Tracking
      2. 9.3.2 Low Temperature Drift
      3. 9.3.3 Load Current
    4. 9.4 Device Functional Modes
  10. 10Applications and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Low-Side, Current-Sensing Application
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
          1. 10.2.1.2.1 Shunt Resistor
          2. 10.2.1.2.2 Differential Amplifier
          3. 10.2.1.2.3 Voltage Reference
          4. 10.2.1.2.4 Results
        3. 10.2.1.3 Application Curves
  11. 11Power-Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 接收文档更新通知
    3. 13.3 支持资源
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 术语表
  14. 14Mechanical, Packaging, and Orderable Information

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10.2.1.2.2 Differential Amplifier

The differential amplifier used for this design should have the following features:

  1. Single-supply (3 V),
  2. Reference voltage input,
  3. Low initial input offset voltage (VOS),
  4. Low-drift,
  5. Fixed gain, and
  6. Low-side sensing (input common-mode range below ground).

For this design, a current-shunt monitor (INA213) is used. The INA21x family topology is shown in Figure 10-3. The INA213B specifications can be found in the INA213 product data sheet.

GUID-8AB741FE-E379-49E1-B58E-696EE0E68013-low.gifFigure 10-3 INA21x Current-Shunt Monitor Topology

The INA213B is an excellent choice for this application because all the required features are included. In general, instrumentation amplifiers (INAs) do not have the input common-mode swing to ground that is essential for this application. In addition, INAs require external resistors to set their gain, which is not desirable for low-drift applications. Difference amplifiers typically have larger input bias currents, which reduce solution accuracy at small load currents. Difference amplifiers typically have a gain of 1 V/V. When the gain is adjustable, these amplifiers use external resistors that are not conducive to low-drift applications.