SBOSAK2A May   2025  – September 2025 INA187

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Amplifier Input Common-Mode Signal
      2. 6.3.2 Low Input Bias Current
      3. 6.3.3 Low VSENSE Operation
      4. 6.3.4 Wide Fixed Gain Output
      5. 6.3.5 Wide Supply Range
    4. 6.4 Device Functional Modes
      1. 6.4.1 Adjusting the Output With the Reference Pin
      2. 6.4.2 Reference Pin Connections for Unidirectional Current Measurements
        1. 6.4.2.1 Ground Referenced Output
        2. 6.4.2.2 VS Referenced Output
      3. 6.4.3 Reference Pin Connections for Bidirectional Current Measurements
        1. 6.4.3.1 Output Set to External Reference Voltage
        2. 6.4.3.2 Output Set to Mid-Supply Voltage
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 RSENSE and Device Gain Selection
    2. 7.2 Typical Application
      1. 7.2.1 Low-side Current Sensing in Motor Application
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
        3. 7.2.1.3 Application Performance Plots
    3. 7.3 Power Supply Recommendations
      1. 7.3.1 Power Supply Decoupling
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Examples
  9. 8 Device and Documentation Support
    1. 8.1 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 Mechanical Data

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • DBV|6
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.1.1 RSENSE and Device Gain Selection

The accuracy of any current-sense amplifier is maximized by choosing the largest current-sense resistor value possible. A larger value 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 value can be in a given application because of the physical dimensions of the package, package construction, and maximum power dissipation. Equation 2 gives the maximum value for the current-sense resistor for a given power dissipation budget:

Equation 2. INA187

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. To verify 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 exceeding the positive swing limitation.

Equation 3. INA187

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 of the device as specified in the Specifications.

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 4 provides the limit on the minimum value of the sense resistor.

Equation 4. INA187

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 as specified in the Specifications.

Table 7-1 shows an example of the different results obtained from using five different gain versions of the INA187. From the table data, the highest gain device allows a smaller current-shunt resistor and decreased power dissipation in the element.

Table 7-1 RSENSE Selection and Power Dissipation(1)
PARAMETER EQUATION RESULTS AT VS = 5V
A1 DEVICES A2 DEVICES A3 DEVICES
G Gain 20V/V 50V/V 100V/V
VSENSE Ideal differential input voltage VSENSE = VOUT / G 250mV 100mV 50mV
RSENSE Current sense resistor value RSENSE = VSENSE / IMAX 25mΩ 10mΩ 5mΩ
PSENSE Current-sense resistor power dissipation RSENSE × IMAX2 2.5W 1W 0.5W
(1) Design example with 10A full-scale current with maximum output voltage set to 5V.