SBOSAG2 june   2023 INA351A

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Device Comparison Table
  7. 6 Pin Configuration and Functions
  8. 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
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Gain-Setting
        1. 8.3.1.1 Gain Error and Drift
      2. 8.3.2 Input Common-Mode Voltage Range
      3. 8.3.3 EMI Rejection
      4. 8.3.4 Typical Specifications and Distributions
      5. 8.3.5 Electrical Overstress
    4. 8.4 Device Functional Modes
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Reference Amplifier
      2. 9.1.2 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
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Development Support
        1. 10.1.1.1 PSpice® for TI
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • DSG|8
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.1.1 Reference Amplifier

The output voltage of the INA351A is developed with respect to the voltage on the pin A_OUT. The voltage on the A_OUT pin sets the common-mode voltage of the instrumentation amplifier OUT pin. In single-supply operation with a bipolar input, setting the output common-mode to a precise mid-supply level is useful and required (for example, 2.75-V in a 5.5-V supply environment) to allow the output signal to swing negative and positive in equal proportions. Traditionally, this is accomplished using a resistive divider from supply and an external reference buffer.

In INA351A, the reference amplifier is integrated on-chip and it is sufficient to only have the resistive divider from supply. With that, the reference amplifier can be connected in G = 1 as shown in Figure 9-1 to provide buffered reference voltage internally to the INA as well as to additional circuits for external use.

Moreover, INA351A has a provision to include servo loop based calibration for external DC offset, drift from the sensor as well as the internal INA offset, drift. This is accomplished using the internal reference amplifier and the three external passive components (R1, R2, and C2) as shown in Figure 9-2. The ratio of resistors R2 with respect to R1 sets the gain in the calibration loop to attenuate the DC errors at lower frequencies around DC. At higher frequencies, the capacitor, C2 shorts R2 to put the reference buffer in G = 1. This enables the instrumentation amplifier's input differential voltage to influence the INA output at higher frequencies while the reference amplifier in servo loop influences the INA output at lower frequencies around DC. Care should be taken to limit the gain in servo loop so as to maintain sufficient stability. Also, the value of C2, R2 should be chosen based on the frequency of input signal at the INA input. Now, the resulting residual DC error after calibration would be that of the reference amplifier itself which is minor in comparison to higher DC offset from the instrumentation amplifier, sensor.

GUID-20230527-SS0I-KJJK-PGBN-BK4NNPVWJHJV-low.svg Figure 9-1 INA351A in Reference Buffer Configuration
GUID-20230527-SS0I-TXH9-DWHV-JPLQKKTRHJKM-low.svg Figure 9-2 INA351A in Servo-Loop Calibration Configuration