SBOS945B November   2020  – April 2021 INA849

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 Adjustable Gain Setting
      2. 8.3.2 Gain Drift
      3. 8.3.3 Wide Input Common-Mode Range
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Reference Pin
      2. 9.1.2 Input Bias Current Return Path
      3. 9.1.3 Thermal Effects due to Power Dissipation
    2. 9.2 Typical Application
      1. 9.2.1 Sensor Conditioning Circuit
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
      2. 9.2.2 Phantom Power in Microphone Preamplifier Circuit
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    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 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.1.2 Detailed Design Procedure

If the instrumentation amplifier is used to drive ac-coupled input signals, an input bias current path must be provided as described in Section 9.1.2, represented with resistors R1 and R2 in Figure 9-6. For the selection of the resistor value, a trade-off must be made between input current noise that increases at lower values and input voltage noise that increases at higher values.

Section 9.1.1 states that the reference pin must be connected to a low-impedance reference, as shown in the application circuit example of the Figure 9-6. The reference pin must be connected to a 2.5-V reference voltage established through a high-resistive divider. The OPA192 helps to buffer the reference voltage. The effective output impedance of the OPA192 is derived as follows. The dc open-loop impedance of the OPA192 amplifier is approximately 3 kΩ. In a buffer configuration (AV = 1), the output impedance of an amplifier degrades by the open-loop voltage gain. The OPA192 specifies a typical AOL of 126 dB, thereby resulting in an output impedance of ROUT = 1.5 mΩ.