SBOSAC3B July   2023  – August 2025 INA745A , INA745B

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 Timing Requirements (I2C)
    7. 5.7 Timing Diagram
    8. 5.8 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 Integrated Shunt Resistor
      2. 6.3.2 Safe Operating Area
      3. 6.3.3 Versatile Measurement Capability
      4. 6.3.4 Internal Measurement and Calculation Engine
      5. 6.3.5 High-Precision Delta-Sigma ADC
        1. 6.3.5.1 Low Latency Digital Filter
        2. 6.3.5.2 Flexible Conversion Times and Averaging
      6. 6.3.6 Integrated Precision Oscillator
      7. 6.3.7 Multi-Alert Monitoring and Fault Detection
    4. 6.4 Device Functional Modes
      1. 6.4.1 Shutdown Mode
      2. 6.4.2 Power-On Reset
    5. 6.5 Programming
      1. 6.5.1 I2C Serial Interface
        1. 6.5.1.1 Writing to and Reading Through the I2C Serial Interface
        2. 6.5.1.2 High-Speed I2C Mode
        3. 6.5.1.3 SMBus Alert Response
  8. 7 Register Maps
    1. 7.1 INA745x Registers
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Device Measurement Range and Resolution
      2. 8.1.2 ADC Output Data Rate and Noise Performance
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Configure the Device
        2. 8.2.2.2 Set Desired Fault Thresholds
        3. 8.2.2.3 Calculate Returned Values
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

6.3.5.2 Flexible Conversion Times and Averaging

ADC conversion times for bus voltage can be set independently from 50μs to 4.12ms. The total conversion time for current includes an additional conversion time for temperature, and can be varied from 100μs to 8.24ms. The flexibility in conversion time allows for robust operation in a variety of noisy environments. The device also allows for programmable averaging times from a single conversion all the way to an average of 1024 conversions. The amount of averaging selected applies uniformly to all active measurement inputs. The ADC_CONFIG register shown in Table 7-4 provides additional details on the supported conversion times and averaging modes. The INA745x effective resolution of the ADC can be increased by increasing the conversion time and increasing the number of averages. Figure 6-9 and Figure 6-10 shown below illustrate the effect of conversion time and averaging on a constant input signal.

INA745A INA745B Noise vs Conversion Time (Averaging = 1) Figure 6-9 Noise vs Conversion Time (Averaging = 1)
INA745A INA745B Noise vs Conversion Time (Averaging = 128) Figure 6-10 Noise vs Conversion Time (Averaging = 128)

Settings for the conversion time and number of conversions averaged impact the effective measurement resolution. For more detailed information on how averaging reduces noise and increases the effective number of bits (ENOB) see ADC Output Data Rate and Noise Performance.