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ISO7341C: Need of pull up on I2C line ?

Part Number: ISO7341C
Other Parts Discussed in Thread: TPS23861, ISO1541, ISO1540

Hi team,

ISO7341C will be used between PSE(TPS23861) and MCU for I2C interface. Can you please review below schematic?

 -. Does it need pull up resistor on I2C line?

 -. ISO7341C port is open drain or push pull?





Sam Lee

  • Hi Sam,

    The schematic looks fine. Just a one comment.

    Although the EN can be left floating, I would still recommend tying EN1 to VCC1 and EN2 to VCC2 using 4.7k resistors, instead of leaving them floating as in the schematic. This would help improve the EMI/EMC performance of the system.

    I am not sure why the bidirectional I2C communication is implemented using a digital isolator in this system. Could you please clarify?
    We have an isolated I2C device which can be used directly without any additional circuitry. ISO1540 / ISO1541. Any reason this is not considered for this application?

    Regarding your other concerns, I would recommend taking a look at the app note Designing I2C using Digital Isolator. This should explain the circuitry required when using a digital isolator as an I2C.
    ISO7341C is push pull architecture output.

    Anand Reghunathan

  • Hi Anand,

    Thank you for your review. The reason why ISO7341 is used rather than ISO1540 is because PSE(TPS23861) needs 3ch for I2C interface.

    Sam Lee