ZHCS766B February   2012  – January 2025 INA230

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Device Comparison
  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 Timing Requirements (I2C)
    7. 6.7 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 Power Calculation
      3. 7.3.3 Alert Pin
    4. 7.4 Device Functional Modes
      1. 7.4.1 Averaging and Conversion Time Considerations
      2. 7.4.2 Filtering and Input Considerations
    5. 7.5 Programming
      1. 7.5.1 Programming the Calibration Register
      2. 7.5.2 Programming the INA230 Power Measurement Engine
        1. 7.5.2.1 Calibration Register and Scaling
      3. 7.5.3 Simple Current Shunt Monitor Usage (No Programming Necessary)
      4. 7.5.4 Default INA230 Settings
      5. 7.5.5 Bus Overview
        1. 7.5.5.1 Serial Bus Address
        2. 7.5.5.2 Serial Interface
      6. 7.5.6 Writing to and Reading From the I2C Serial Interface
        1. 7.5.6.1 High-Speed I2C Mode
      7. 7.5.7 SMBus Alert Response
    6. 7.6 Register Maps
      1. 7.6.1 Configuration Register (00h, Read/Write)
      2. 7.6.2 AVG Bit Settings [11:9]
      3. 7.6.3 VBUS CT Bit Settings [8:6]
      4. 7.6.4 VSH CT Bit Settings [5:3]
      5. 7.6.5 Mode Settings [2:0]
      6. 7.6.6 Data Output Register
        1. 7.6.6.1 Shunt Voltage Register (01h, Read-Only)
        2. 7.6.6.2 Bus Voltage Register (02h, Read-Only) #GUID-A37EA2E7-DC60-42D5-94EF-920B5CD5B7A9/SBOS5477597
        3. 7.6.6.3 Power Register (03h, Read-Only)
        4. 7.6.6.4 Current Register (04h, Read-Only)
        5. 7.6.6.5 Calibration Register (05h, Read/Write)
        6. 7.6.6.6 Mask/Enable Register (06h, Read/Write)
        7. 7.6.6.7 Alert Limit Register (07h, Read/Write)
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 High-Side Sensing Circuit Application
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 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 接收文档更新通知
    3. 9.3 支持资源
    4. 9.4 Trademarks
    5. 9.5 静电放电警告
    6. 9.6 术语表
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.5.1 Programming the Calibration Register

Figure 8-1 shows a nominal 10A load that creates a differential voltage of 20mV across a 2mΩ shunt resistor. The bus voltage for the INA230 is measured at the external VBUS input pin, which in this example is connected to the IN– pin to measure the voltage level delivered to the load. For this example, the VBUS pin measures less than 12V because the voltage at the IN– pin is 11.98V as a result of the voltage drop across the shunt resistor.

For this example, assuming a maximum expected current of 15A, the Current_LSB is calculated to be 457.7μA/bit using Equation 2. Using a value for the Current_LSB of 500μA/bit or 1mA/bit significantly simplifies the conversion from the Current register (04h) and Power register (03h) to amperes and watts. For this example, a value of 1mA/bit was chosen for the Current_LSB. Using this value for the Current_LSB does trade a small amount of resolution for having a simpler conversion process on the user side. Using Equation 1 in this example with a Current_LSB value of 1mA/bit and a shunt resistor of 2mΩ results in a Calibration register value of 2560, or A00h.

The Current register (04h) is then calculated by multiplying the decimal value of the Shunt Voltage register (01h) contents by the decimal value of the Calibration register and then dividing by 2048, as shown in Equation 3. For this example, the Shunt Voltage register contains a value of 8,000 (representing 20mV), which is multiplied by the Calibration register value of 2560 and then divided by 2048 to yield a decimal value for the Current register (04h) of 10000, or 2710h. Multiplying this value by 1mA/bit results in the original 10A level stated in the example.

Equation 3. C u r r e n t = S h u n t × C a l i b r a t i o n R e g i s t e r 2048

The LSB for the Bus Voltage register (02h) is a fixed 1.25mV/bit, which means that the 11.98V present at the VBUS pin results in a register value of 2570h, or a decimal equivalent of 9584. Note that the MSB of the Bus Voltage register (02h) is always zero because the VBUS pin is only able to measure positive voltages.

The Power register (03h) is then calculated by multiplying the decimal value of the Current register, 10000, by the decimal value of the Bus Voltage register (02h), 9584, and then dividing by 20,000, as defined in Equation 4. For this example, the result for the Power register (03h) is 12B8h, or a decimal equivalent of 4792. Multiplying this result by the power LSB (25 times the [1 × 10–3 Current_LSB]) results in a power calculation of (4792 × 25mW/bit), or 119.82W. The power LSB has a fixed ratio to the Current_LSB of 25. For this example, a programmed 1mA/bit Current_LSB results in a power LSB of 25 mW/bit. This ratio is internally programmed to verify that the scaling of the power calculation is within an acceptable range. A manual calculation for the power being delivered to the load uses a bus voltage of 11.98V (12VCM – 20mV shunt drop) multiplied by the load current of 10A to give a result of 119.8W.

Equation 4. P o w e r = C u r r e n t × B u s V o l t a g e 20 , 000

Table 7-1 lists the steps for configuring, measuring, and calculating the values for current and power for this device.

Table 7-1 Calculating Current and Power(1)
STEPREGISTER NAMEADDRESSCONTENTSDECLSBVALUE
Step 1Configuration register00h4127h———
Step 2Shunt register01h1F40h80002.5µV20mV
Step 3Bus Voltage register02h2570h95841.25mV11.98V
Step 4Calibration register05hA00h2560——
Step 5Current register04h2710100001mA10A
Step 6Power register03h12B8h479225mW119.82W
(1) Conditions: Load = 10A, VCM = 12V, RSHUNT = 2mΩ, and VVBUS = 12V.