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INA233: Register Map

Johnson Cheah
Intellectual 1300 points
Part Number: INA233
Other Parts Discussed in Thread: ISO1541

Hi Team,

There are a lot of registers and what is the fundamental registers that must be configure in order for INA233 to work properly? I just want to read the current and voltage from INA233 only.  

  • 0
    TI__Mastermind 31485 points

    Hello Johnson,

    If you want the INA233 to read back current values, then the MFR_CALIBRATION PMBus command (D4h) must be executed once after every power reset. In Table 4 all of the PMBus commands are listed and these can be thought of as just registers.

    Programming the MFR_CALIBRATION register gives the device what the shunt resistor value is along with some scaling so it can perform the calculation internally.

    After programming D4h, the INA233 will begin generating current and voltage measurements immediately because this is its default programming according to the default value of MFR_ADC_CONFIG (D0h).

    You obtain current and voltage measurements from codes 89h and 88h respectively.

    Sincerely,

    Peter

  • 0 in reply to Peter Iliya
    Prodigy 215 points

    Hi Thanks for the explanation ,

      However I would like to know  ,How do we calculate what  value to be put in MFR_CALIBRATION register .

    Say we Have a shunt of rating 300A/50mV .How can we use this to make current reading from READ_IN (0X89) Register.

    Can you please explain , I think it will help to many people.

       

  • 0 in reply to Jitender Singh
    TI__Mastermind 31485 points

    Hey Jitender,

    Equations 1 and 2 of datasheet show how to calculate this value. There is also an example calculation in the applications section of the datasheet. You need to determine the maximum current you will measure in your application to set a current LSB.

    Hope this helps.

    Peter

  • 0 in reply to Peter Iliya
    Prodigy 215 points

    Well thanks for the same .

    I have a new query based on my experience.

    IN the following diagram based on one of your application notes.

    I am using INA 233 instead of INA 226.

    My question is : If we connect Vin+ to the upper end of the shunt voltage , there is a considerable drop in the Vbus Voltage around 4-5 Volts.

    Can you please provide some hint what could be the issue , how to resolve it.

      

  • 0 in reply to Jitender Singh
    Prodigy 215 points

    Resolved , there was a wrong connection .R2 other end was connected to vin+.

  • 0 in reply to Jitender Singh
    Prodigy 215 points

    Hi  Friends , 

      Facing one more issue  ,  The sda line is not pulled down properly by the INA 233 in case of acknowledgment bit from the slave i.e INA 233.

    Due to this the data is also not getting proper.Attching the screenshot .Please suggest what could be the issue.

    Sda not pulled low properly by slave (ina 233) on ninth pulse from the master (mcu).

    Using 10k pullup on sda, scl  on both sides of ISO1541.

     

  • 0 in reply to Jitender Singh
    TI__Mastermind 31485 points

    Hey Jitender,

    Could you zoom into the 8th and 9th clock cycles? It seems like once INA233 takes control of SCL is supposed to hold SCL low (ACK), it stops at ~0.9V.

    Would you be able to explain why the 8th and 9th SCL clock pulses from master are so close together? Maybe this is violating the t_SUDAT (data setup time) of INA233.

    Are you also taking into consideration the threshold voltages of the ISO1541? The testing conditions for the low-level output voltages show the SDA and SCL currents greater than 0.5mA; however, your bus voltage seems to only reach 4V. With the 10kOhm resistors this equates to 400uA and is not a valid condition for the device.

     

    I would recommend attempting communication without the ISO1541. If this does not fix the issue, then I would reduce the pull-up resistance to 4.7kOhm. If this does not work, try understanding why the master’s 8th and 9th SCL cycles are so close. Perhaps this could be a firmware fix.

    Sincerely,

    Peter Iliya