SBOS776D March   2016  – September 2026 INA3221-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Basic ADC Functions
      2. 7.3.2 Alert Monitoring
        1. 7.3.2.1 Critical Alert
          1. 7.3.2.1.1 Summation Control Function
        2. 7.3.2.2 Warning Alert
        3. 7.3.2.3 Power-Valid Alert
        4. 7.3.2.4 Timing-Control Alert
        5. 7.3.2.5 Default Settings
      3. 7.3.3 Software Reset
    4. 7.4 Device Functional Modes
      1. 7.4.1 Averaging Function
      2. 7.4.2 Multiple Channel Monitoring
        1. 7.4.2.1 Channel Configuration
        2. 7.4.2.2 Averaging and Conversion-Time Considerations
      3. 7.4.3 Filtering and Input Considerations
    5. 7.5 Programming
      1. 7.5.1 Bus Overview
        1. 7.5.1.1 Serial Bus Address
        2. 7.5.1.2 Serial Interface
      2. 7.5.2 Writing To and Reading From the INA3221-Q1
        1. 7.5.2.1 High-Speed I2C Mode
      3. 7.5.3 SMBus Alert Response
  9. 8 Register Maps
    1. 8.1 Summary of Register Set
    2. 8.2 Register Descriptions
      1. 8.2.1  Configuration Register (address = 00h) [reset = 7127h]
      2. 8.2.2  Channel-1 Shunt-Voltage Register (address = 01h), [reset = 00h]
      3. 8.2.3  Channel-1 Bus-Voltage Register (address = 02h) [reset = 00h]
      4. 8.2.4  Channel-2 Shunt-Voltage Register (address = 03h) [reset = 00h]
      5. 8.2.5  Channel-2 Bus-Voltage Register (address = 04h) [reset = 00h]
      6. 8.2.6  Channel-3 Shunt-Voltage Register (address = 05h) [reset = 00h]
      7. 8.2.7  Channel-3 Bus-Voltage Register (address = 06h) [reset = 00h]
      8. 8.2.8  Channel-1 Critical-Alert Limit Register (address = 07h) [reset = 7FF8h]
      9. 8.2.9  Warning-Alert Channel-1 Limit Register (address = 08h) [reset = 7FF8h]
      10. 8.2.10 Channel-2 Critical-Alert Limit Register (address = 09h) [reset = 7FF8h]
      11. 8.2.11 Channel-2 Warning-Alert Limit Register (address = 0Ah) [reset = 7FF8h]
      12. 8.2.12 Channel-3 Critical-Alert Limit Register (address = 0Bh) [reset = 7FF8h]
      13. 8.2.13 Channel-3 Warning-Alert Limit Register (address = 0Ch) [reset = 7FF8h]
      14. 8.2.14 Shunt-Voltage Sum Register (address = 0Dh) [reset = 00h]
      15. 8.2.15 Shunt-Voltage Sum-Limit Register (address = 0Eh) [reset = 7FFEh]
      16. 8.2.16 Mask/Enable Register (address = 0Fh) [reset = 0002h]
      17. 8.2.17 Power-valid Upper-limit Register (address = 10h) [reset = 2710h]
      18. 8.2.18 Power-Valid Lower-Limit Register (address = 11h) [reset = 2328h]
      19. 8.2.19 Manufacturer ID Register (address = FEh) [reset = 5449h]
      20. 8.2.20 Die ID Register (address = FFh) [reset = 3220]
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 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
    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. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

8.2.2 Channel-1 Shunt-Voltage Register (address = 01h), [reset = 00h]

This register contains the averaged shunt-voltage measurement for channel 1. This register stores the current shunt-voltage reading, VSHUNT, for channel 1. Negative numbers are represented in twos complement format. Generate the twos complement of a negative number by complementing the absolute value binary number and adding 1. Extend the sign, denoting a negative number by setting MSB = 1.

Full-scale range = 163.8mV (decimal = 7FF8); LSB (SD0): 40μV.

Example: For a value of VSHUNT = –80mV:

  1. Take the absolute value: 80mV
  2. Translate this number to a whole decimal number (80mV / 40µV) = 2000
  3. Convert this number to binary = 011 1110 1000 0_ _ _ (last three bits are set to 0)
  4. Complement the binary result = 100 0001 0111 1111
  5. Add 1 to the complement to create the twos complement result = 100 0001 1000 0000
  6. Extend the sign and create the 16-bit word: 1100 0001 1000 0000 = C180h

Table 8-5 Channel-1 Shunt-Voltage Register
1514131211109876543210
SIGNSD11SD10SD9SD8SD7SD6SD5SD4SD3SD2SD1SD0———
R-0R-0R-0R-0R-0R-0R-0R-0R-0R-0R-0R-0R-0R-0R-0R-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 8-6 Channel-1 Shunt-Voltage Register Field Descriptions
BitFieldTypeResetDescription
15SIGNR0hSign bit.
0 = positive number
1 = negative number in twos complement format
14-3SD11-0R0hChannel-1 shunt-voltage data bits
2-0ReservedR0hReserved