ZHCSC46C February   2014  – June 2021 INA300


  1. 特性
  2. 应用
  3. 说明
  4. Revision History
  5. Pin Configuration and Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings (1)
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7. 6.7 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Selecting a Current-Sensing Resistor
        1. Selecting a Current-Sensing Resistor: Example
      2. 7.3.2 Setting The Current-Limit Threshold
        1. Resistor-Controlled Current Limit
        2. Voltage Source-Controlled Current Limit
      3. 7.3.3 Delay Setting
      4. 7.3.4 Alert Timing Response
      5. 7.3.5 Selectable Hysteresis
      6. 7.3.6 Alert Output
      7. 7.3.7 Noise Adjustment Factor (NAF)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Alert Mode
        1. Transparent Output Mode
        2. Latch Output Mode
      2. 7.4.2 Disable Mode
      3. 7.4.3 Input Filtering
      4. 7.4.4 Using the INA300 INA300 With Common-Mode Transients Above 36 V
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Unidirectional Operation
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curve
      2. 8.2.2 Bidirectional Operation
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curve
      3. 8.2.3 Window Comparator
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curve
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  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 Electrostatic Discharge Caution
    6. 11.6 术语表
  12. 12Mechanical, Packaging, and Orderable Information


机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)

Selecting a Current-Sensing Resistor

The device measures the differential voltage developed across a resistor when current flows through it to determine if the monitored current exceeds a defined limit. This resistor is referred to as a current-sensing resistor or a current-shunt resistor, with each term used interchangeably. The flexible design of the device allows for measuring a wide differential input signal range across this current-sensing resistor, which can extend up to 250 mV.

Selecting the value of this current-sensing resistor is based primarily on two factors: the required accuracy of the current measurement and the allowable power dissipation across the current-sensing resistor. Larger voltages developed across this resistor allow more accurate measurements. This large signal accuracy improvement results from the fixed internal amplifier errors that are dominated by the inherent input offset voltage of the device. When the input signal decreases, these fixed internal amplifier errors become a larger portion of the measurement and increase the uncertainty in the measurement accuracy. When the input signal increases, the measurement uncertainty is reduced because the fixed errors are a smaller percentage of measured signal.

A system design trade-off for improving the measurement accuracy using larger input signals is the increase in power across the current-sensing resistor. Increasing the value of the current-shunt resistor increases the differential voltage developed across the resistor when current passes through the component. This increase in voltage across the resistor increases the power that the resistor must be able to dissipate. Decreasing the value of the current-shunt resistor value reduces the power dissipation requirements of the resistor, but increases the measurement errors resulting from the decreased input signal. Selecting the optimal value for the shunt resistor requires factoring both the accuracy requirement for the specific application and the allowable power dissipation of this component.

An increasing number of low ohmic-value resistors are becoming available with values as low as 200 µΩ, with power dissipations of up to 5 W that enable large currents to be monitored with sensing resistors.