SBOSAC3A July   2023  – December 2023 INA745A , INA745B

PRODMIX  

  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 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Device Measurement Range and Resolution
      2. 7.1.2 ADC Output Data Rate and Noise Performance
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Configure the Device
        2. 7.2.2.2 Set Desired Fault Thresholds
        3. 7.2.2.3 Calculate Returned Values
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
    5. 7.5 Register Maps
      1. 7.5.1 INA745x Registers
  9. 8 Device and Documentation Support
    1. 8.1 Receiving Notification of Documentation Updates
    2. 8.2 Support Resources
    3. 8.3 Trademarks
    4. 8.4 Electrostatic Discharge Caution
    5. 8.5 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

7.2.3 Application Curves

Figure 7-3 and Figure 7-4 show the ALERT pin response to an overcurrent fault with a conversion time of 50 μs for the temperature, shunt voltage, and bus voltage measurements with averaging set to 1. This configuration results in a total conversion time of 150 μs for all three measurements. For these scope shots, persistence was enabled on the ALERT channel to show the variation in the alert response for many sequential fault events. The alert response time can change depending on the value of the current before fault occurs as well as the how much the fault condition exceeds the programmed fault threshold. Figure 7-3 shows the response time for an overcurrent fault when the fault condition greatly exceeds the programmed threshold, while Figure 7-4 shows the overcurrent response time when the fault slightly exceeds the programmed threshold. Variation in the alert response exists because the external fault event is not synchronized to the internal ADC conversion start. Also the ADC is constantly sampling to get a result, so the response time for fault events starting from zero will be slower than fault events starting from values near the set fault threshold. In applications where the alert timing is critical for overcurrent events, the worst-case alert response is equal to 2 × tconv_current + tconv_temp + tconv_voltage + 25 μs. An additional 25 μs is added to allow for background math calculations. This equation does not account for the 1% oscillator tolerance and is only valid for cases where the overcurrent signal is greater than the conversion threshold and noise. The measurement noise is a function of the conversion time. See Section 6.3.5.2 and Section 7.1.2 for additional information.

Figure 7-4 shows a slightly longer worst case alert response because the alert threshold is within the noise band of the device measurement and signal.
GUID-20231218-SS0I-FGNC-WJQN-D67HMZSNPJ35-low.svgFigure 7-3 Alert Response Time (Sampled Values Significantly Above Threshold)
GUID-20231218-SS0I-CMPS-PMXX-GC65R9VVQWNQ-low.svgFigure 7-4 Alert Response Time (Sampled Values Slightly Above Threshold)