SBOSA20A February   2021  – May 2022 INA237

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 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 Timing Diagram
    8. 6.8 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Versatile High Voltage Measurement Capability
      2. 7.3.2 Power Calculation
      3. 7.3.3 Low Bias Current
      4. 7.3.4 High-Precision Delta-Sigma ADC
        1. 7.3.4.1 Low Latency Digital Filter
        2. 7.3.4.2 Flexible Conversion Times and Averaging
      5. 7.3.5 Integrated Precision Oscillator
      6. 7.3.6 Multi-Alert Monitoring and Fault Detection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Power-On Reset
    5. 7.5 Programming
      1. 7.5.1 I2C Serial Interface
        1. 7.5.1.1 Writing to and Reading Through the I2C Serial Interface
        2. 7.5.1.2 High-Speed I2C Mode
        3. 7.5.1.3 SMBus Alert Response
    6. 7.6 Register Maps
      1. 7.6.1 INA237 Registers
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Device Measurement Range and Resolution
      2. 8.1.2 Current and Power Calculations
      3. 8.1.3 ADC Output Data Rate and Noise Performance
      4. 8.1.4 Input Filtering Considerations
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Select the Shunt Resistor
        2. 8.2.2.2 Configure the Device
        3. 8.2.2.3 Program the Shunt Calibration Register
        4. 8.2.2.4 Set Desired Fault Thresholds
        5. 8.2.2.5 Calculate Returned Values
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.5.1.1 Writing to and Reading Through the I2C Serial Interface

Accessing a specific register on the INA237 is accomplished by writing the appropriate value to the register pointer. Refer to Section 7.6 for a complete list of registers and corresponding addresses. The value for the register pointer (as shown in Figure 7-9) is the first byte transferred after the secondary device address byte with the R/W bit low. Every write operation to the device requires a value for the register pointer.

Writing to a register begins with the first byte transmitted by the main device. This byte is the secondary device address, with the R/W bit low. The device then acknowledges receipt of a valid address. The next byte transmitted by the main device is the address of the register to be accessed. This register address value updates the register pointer to the desired internal device register. The next two bytes are written to the register addressed by the register pointer. The device acknowledges receipt of each data byte. The main device may terminate data transfer by generating a start or stop condition.

When reading from the device, the last value stored in the register pointer by a write operation determines which register is read during a read operation. To change the register pointer for a read operation, a new value must be written to the register pointer. This write is accomplished by issuing a secondary device address byte with the R/ W bit low, followed by the register pointer byte. No additional data are required. The main device then generates a start condition and sends the address byte for the secondary device with the R/W bit high to initiate the read command. The next byte is transmitted by the secondary device and is the most significant byte of the register indicated by the register pointer. This byte is followed by an Acknowledge from the main device; then the secondary device transmits the least significant byte. The main device may or may not acknowledge receipt of the second data byte. The main device may terminate data transfer by generating a Not-Acknowledge after receiving any data byte, or generating a start or stop condition. If repeated reads from the same register are desired, it is not necessary to continually send the register pointer bytes; the device retains the register pointer value until it is changed by the next write operation.

Figure 7-7 shows the write operation timing diagram. Figure 7-8 shows the read operation timing diagram. These diagrams are shown for reading/writing to 16 bit registers.

Register bytes are sent most-significant byte first, followed by the least significant byte.

A. The value of the Secondary Device Address byte is determined by the settings of the A0 and A1 pins. Refer to Table 7-2.
B. The device does not support packet error checking (PEC) or perform clock stretching.
Figure 7-7 Timing Diagram for Write Word Format
A. The value of the Secondary Device Address byte is determined by the settings of the A0 and A1 pins. Refer to Table 7-2.
B. Read data is from the last register pointer location. If a new register is desired, the register pointer must be updated. See Figure 7-9.
C. ACK by the main device can also be sent.
D. The device does not support packet error checking (PEC) or perform clock stretching.
Figure 7-8 Timing Diagram for Read Word Format
A. The value of the Secondary Device Address Byte is determined by the settings of the A0 and A1 pins. Refer to Table 7-2.
Figure 7-9 Typical Register Pointer Set