SBOSA75B July   2021  – November 2021 INA823

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and 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 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Gain-Setting Function
        1. 8.3.1.1 Gain Drift
      2. 8.3.2 Input Common-Mode Voltage Range
      3. 8.3.3 Input Protection
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Input Bias Current Return Path
    2. 9.2 Typical Applications
      1. 9.2.1 Resistive-Bridge Pressure Sensor
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Supporting High Common-Mode Voltage in PLC Input Modules
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
        1. 12.1.1.1 PSpice® for TI
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.2 Input Common-Mode Voltage Range

The INA823 linear input voltage range extends from 1 V less than the positive supply to 0.15 V less than the negative supply, and maintains excellent common-mode rejection throughout this range. The common-mode range for the most common operating conditions are shown in Figure 8-3. While there are other methods to calculate the common-mode voltage range, the suggested tool is the Analog Engineers Calculator.

GUID-20210616-CA0I-2ZVR-SJJM-XZHTQ0L7MCVN-low.png
VS = 5 V, G = 1
Figure 8-3 Input Common-Mode Voltage vs Output Voltage
GUID-20210616-CA0I-RPWH-NGR8-J3XM3CRMQM0J-low.png
G = 1, VREF = 0 V
Figure 8-5 Input Common-Mode Voltage vs Output Voltage
GUID-20210616-CA0I-MGHF-T38Z-VCTFH8HXW7GS-low.png
VS = 5 V, G = 100
Figure 8-4 Input Common-Mode Voltage vs Output Voltage
GUID-20210616-CA0I-NGPZ-G3XF-VZN7PFXCTB5M-low.png
G > 10, VREF = 0 V
Figure 8-6 Input Common-Mode Voltage vs Output Voltage

A single-supply instrumentation amplifier has special design considerations. To achieve a common-mode range that extends to single-supply ground, the INA823 employs a current-feedback topology with PNP input transistors. The matched PNP transistors, Q1 and Q2, shift the input voltages of both inputs up by a diode drop, and (through the feedback network) shift the output of A1 and A2 by approximately 0.6 V. The output of A1 and A2 is well within the linear range when the inputs are within the single-supply ground. When inputs are within the supply ground, differential measurements can be made at the ground level. As a result of this input level-shifting, the voltages at pin 1 and pin 8 are not equal to the respective input pin voltages. For most applications, this inequality is not important because only the gain-setting resistor connects to these pins.