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ISOW7841A-Q1: Designing a reinforced isolated I2C interface by using digital isolator with integrated DCDC

Manuel Woerner
Prodigy 30 points
Part Number: ISOW7841A-Q1
Other Parts Discussed in Thread: INA228-Q1, ISO7731

Tool/software:

Hi TI Team,

currently I'm evaluating different concepts for the reinforced isolation of an I2C signal coming from INA228-Q1 located on the HV side of my system.
I want to cross the isolation barrier through a digital isolator with integrated DCDC like the ISOW7841A-Q1.
The isolated 5V output will be needed to supply the INA228-Q1 as well as some other low-current components.

I would like to implement an isolation by using the same approach described in the following design journal: Designing an Isolated I2C Bus interface by using digital isolators (Rev. A)
There you're using the ISO7731 as digital isolator.

Now I've two questions:

  • Which version of digital isolator do I need, default High or Low active? I guess for I2C interface it should be Default High, as I2C will be low active.
  • Is there also a design reference for a 5V supply voltage VCC1 and VCC2 as the ISOW7841A-Q1 and the INA228-Q1 support this?
    In the design journal the circuit was shown for a 3.3V supply voltage:

Thanks in advance!

BR,
Manuel