SBOS790A April   2017  – March 2025 INA233

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 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 High-Accuracy Analog-to-Digital Convertor (ADC)
      2. 6.3.2 Interleaved Power Calculation
      3. 6.3.3 Power Accumulator and Energy Measurement
      4. 6.3.4 I2C-, SMBus-, and PMBus-Compatible Digital Interface
      5. 6.3.5 Multiple Fault Event Reporting
    4. 6.4 Device Functional Modes
      1. 6.4.1 Continuous Verses Triggered Operation
      2. 6.4.2 Device Shutdown
      3. 6.4.3 Averaging and Conversion Time Considerations
      4. 6.4.4 Filtering and Input Considerations
    5. 6.5 Programming
      1. 6.5.1 Default Settings
      2. 6.5.2 Calibration Register and Scaling
      3. 6.5.3 Reading and Writing Telemetry Data and Warning Thresholds
      4. 6.5.4 Reading Telemetry Data and Warning Thresholds
        1. 6.5.4.1 Writing Telemetry Data and Warning Thresholds
      5. 6.5.5 System-Level Calibration With MFR_CALIRATION Command
      6. 6.5.6 Bus Overview
        1. 6.5.6.1 Serial Bus Address
        2. 6.5.6.2 Serial Interface
        3. 6.5.6.3 Writing to and Reading From the INA233
          1. 6.5.6.3.1 Packet Error Checking
          2. 6.5.6.3.2 Bus Timing Requirements
        4. 6.5.6.4 SMBus Alert Response
    6. 6.6 Register Maps
      1. 6.6.1 PMBus Command Support
      2. 6.6.2 Standard PMBus Commands
        1. 6.6.2.1  CLEAR_FAULTS (03h)
        2. 6.6.2.2  RESTORE_DEFAULT_ALL (12h)
        3. 6.6.2.3  CAPABILITY (19h)
        4. 6.6.2.4  IOUT_OC_WARN_LIMIT (4Ah) [default = 01111111 11111000]
        5. 6.6.2.5  VIN_OV_WARN_LIMIT (57h) [default = 01111111 11111000]
        6. 6.6.2.6  VIN_UV_WARN_LIMIT (58h) [default = 00000000 00000000]
        7. 6.6.2.7  PIN_OP_WARN_LIMIT (6Bh) [default = 11111111 11110000]
        8. 6.6.2.8  STATUS_BYTE (78h)
        9. 6.6.2.9  STATUS_WORD (79h)
        10. 6.6.2.10 STATUS_IOUT (7Bh)
        11. 6.6.2.11 STATUS_INPUT (7Ch)
        12. 6.6.2.12 STATUS_CML (7Eh)
        13. 6.6.2.13 STATUS_MFR_SPECIFIC (80h)
        14. 6.6.2.14 READ_EIN (86h)
        15. 6.6.2.15 READ_VIN (88h)
        16. 6.6.2.16 READ_IIN (89h)
        17. 6.6.2.17 READ_VOUT (8Bh)
        18. 6.6.2.18 READ_IOUT (8Ch, R)
        19. 6.6.2.19 READ_POUT (96h, R)
        20. 6.6.2.20 READ_PIN (97h, R)
        21. 6.6.2.21 MFR_ID (99h)
        22. 6.6.2.22 MFR_MODEL (9Ah)
        23. 6.6.2.23 MFR_REVISION (9Bh)
      3. 6.6.3 Manufacturer-Specific PMBus Commands
        1. 6.6.3.1 MFR_ADC_CONFIG (D0h) [default = 01000001 00100111]
        2. 6.6.3.2 MFR_READ_VSHUNT (D1h) [default = 00000000 00000000]
        3. 6.6.3.3 MFR_ALERT_MASK (D2h) [default = XXXXXXXX 11110000]
        4. 6.6.3.4 MFR_CALIBRATION (D4h) [default = 00000000 00000001]
        5. 6.6.3.5 MFR_DEVICE_CONFIG (D5h) [default = 00000010]
        6. 6.6.3.6 5.1.1 CLEAR_EIN (D6h)
        7. 6.6.3.7 TI_MFR_ID (E0h) [value = 01010100 01001001]
        8. 6.6.3.8 TI_MFR_MODEL (E1h) [value = 00110011 00110011]
        9. 6.6.3.9 TI_MFR_REVISION (E2h) [value = 01000001 00110000]
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Programming the Calibration Register
        2. 7.2.2.2 Calculating PMBus Coefficients
        3. 7.2.2.3 Programming Warning Thresholds
        4. 7.2.2.4 Calculating Returned Telemetry 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
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.5.2 Calibration Register and Scaling

An important aspect of the INA233 is that the device does not necessarily measure current or power. The device measures both the differential voltage applied between the IN+ and IN– input pins and the voltage applied to the VBUS pin. By correctly setting the calibration register scaling with the MFR_CALIBRATION command, returned values are calculated in voltage, amperes, and watts by scaling the returned value by the appropriate lest significant bit value (LSB) or by using the PMBus direct mode equation (Equation 3).

Equation 1 is used to obtain the value for the MFR_CALIGRATION register. This equation includes the term Current_LSB, which is the chosen value for the LSB for the READ_IIN command. As Equation 2 shows, the highest resolution for current measurements can be obtained by using the smallest allowable Current_LSB based on the maximum expected current. Although this value yields the highest resolution, the Current_LSB value is commonly selected as the nearest full number above this value to simplify the conversion of returned values for current and power to amperes and watts, respectively. The RSHUNT term is the value of the external shunt used to develop the differential voltage across the input pins.

Equation 1. C A L =   0.00512 C u r r e n t _ L S B × R S H U N T

where

  • 0.00512 is an internal fixed value used to verify that the scaling is maintained properly
Equation 2. C u r r e n t _ L S B =   M a x i m u m   E x p e c t e d   C u r r e n t 2 15

After programming the calibration register, the values returned by the read current, power, and energy commands update accordingly based on the corresponding shunt voltage and bus voltage measurements.

Returned values for voltage, current, and power are calculated by multiplying the appropriate LSB value by the returned value, or can be calculated with PMBus coefficients as detailed in the Section 6.5.3 section. The size of the Power_LSB is internally set as 25 times the selected Current_LSB. The voltage LSB for bus voltage (READ_VIN and READ_VOUT commands) and shunt voltage (MFR_READ_VSHUNT) are fixed at 1.25mV/bit and 2.5µV/bit, respectively.

The MFR_CALIBRATION command allows the values returned by the READ_IIN and READ_PIN commands to be scaled to the most useful value for a given application. For example, set the MFR_CALIBRATION register so that the largest possible number is returned by the READ_IIN and READ_PIN commands at the expected full-scale point. This approach yields the highest resolution using the previously calculated minimum Current_LSB in Equation 1. The calibration register can also be selected so that READ_IIN and READ_PIN return direct decimal equivalents of the values being measured, or to yield a full LSB value for each corresponding register.