JAJSCL0C July   2016  – December 2021 INA240


  1. 特長
  2. アプリケーション
  3. 概要
  4. Revision History
  5. Device Comparison
  6. Pin Configuration and Functions
  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 Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Amplifier Input Signal
        1. Enhanced PWM Rejection Operation
        2. Input Signal Bandwidth
      2. 8.3.2 Selecting the Sense Resistor (RSENSE)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Adjusting the Output Midpoint With the Reference Pins
      2. 8.4.2 Reference Pin Connections for Unidirectional Current Measurements
        1. Ground Referenced Output
        2. VS Referenced Output
      3. 8.4.3 Reference Pin Connections for Bidirectional Current Measurements
        1. Output Set to External Reference Voltage
        2. Output Set to Midsupply Voltage
        3. Output Set to Mid-External Reference
        4. Output Set Using Resistor Divider
      4. 8.4.4 Calculating Total Error
        1. Error Sources
        2. Reference Voltage Rejection Ratio Error
          1. Total Error Example 1
          2. Total Error Example 2
  9. Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Input Filtering
    2. 9.2 Typical Applications
      1. 9.2.1 Inline Motor Current-Sense Application
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curve
      2. 9.2.2 Solenoid Drive Current-Sense Application
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curve
    3. 9.3 What to Do and What Not to Do
      1. 9.3.1 High-Precision Applications
      2. 9.3.2 Kelvin Connection from the Current-Sense Resistor
  10. 10Power Supply Recommendations
    1. 10.1 Power Supply Decoupling
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Connection to the Current-Sense Resistor
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 サポート・リソース
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information



Input Signal Bandwidth

The INA240 input signal, which represents the current being measured, is accurately measured with minimal disturbance from large ΔV/Δt common-mode transients as previously described. For PWM signals typically associated with motors, solenoids, and other switching applications, the current being monitored varies at a significantly slower rate than the faster PWM frequency.

The INA240 bandwidth is defined by the –3-dB bandwidth of the current-sense amplifier inside the device; see the Section 7.5 table. The device bandwidth provides fast throughput and fast response required for the rapid detection and processing of overcurrent events. Without the higher bandwidth, protection circuitry may not have adequate response time and damage may occur to the monitored application or circuit.

Figure 8-1 shows the performance profile of the device over frequency. Harmonic distortion increases at the upper end of the amplifier bandwidth with no adverse change in detection of overcurrent events. However, increased distortion at the highest frequencies must be considered when the measured current bandwidth begins to approach the INA240 bandwidth.

For applications requiring distortion sensitive signals, Figure 8-1 provides information to show that there is an optimal frequency performance range for the amplifier. The full amplifier bandwidth is always available for fast overcurrent events at the same time that the lower frequency signals are amplified at a low distortion level. The output signal accuracy is reduced for frequencies closer to the maximum bandwidth. Individual requirements determine the acceptable limits of distortion for high-frequency, current-sensing applications. Testing and evaluation in the end application or circuit is required to determine the acceptance criteria and to validate the performance levels meet the system specifications.

GUID-05EC9F25-E0CB-414E-9490-D33AE4D8C961-low.gif Figure 8-1 Performance Over Frequency