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ISO1640-Q1: I2C Isolation Device Application Issue

user1359349
Intellectual 510 points

Part Number: ISO1640-Q1
Other Parts Discussed in Thread: INA237, TCA9509, ISO1640

 hello

     In our new design, we are using multiple TI ICs as listed below:
For the isolation device, we plan to use TI's ISO164x series and need to finalize the specific part number. Based on the diagram below, could you please recommend one?

   The key question is: should side 1 of the ISO164x be connected to the INA237, or side 2? We would appreciate your advice. Thank you.




image.png

  • 0
    TI__Guru 57445 points

    Hi,

    Side1 of ISO164x should only be connected to one node while Side2 can be connected to multiple nodes. Therefore, please connect Side1 to INA237.
    Please make sure the I/O thresholds of INA237 and Side1 and are compatible, if they are not, you may need to use an I2C buffer. 


    Regards,
    Koteshwar Rao

  • 0 in reply to Koteshwar Rao
    Intellectual 510 points

    thanks for your replay,I have confirmed that the I/O thresholds of INA237 and side 1 are not compatible.i have selected an I2C buffer,the TCA9509,and connected SDAA/SCLA to the INA237,and SDAB/SCLB to side 1 of the ISO164x,could you please help check if this configuration is reasonable?also,the TCA9509 requires that VOL-LILc is less than 50 mV,what is this parameter used for ,and what impact does it have on this connection，Looking forward to your reply，thanks

    please check if the buffer i selected is reasonable,if there is any mistake,please recommend on for me ,thank you

  • +1 in reply to user1359349
    TI__Genius 16500 points

    Hi,

    Thanks for the input here.

    Please understand that SideB of TCA must not be connected to Side1 of ISO1640 due to voltage offset limitation on SideB of TCA.

    Please reverse the SIdeA and SideB of TCA and you should be good to go here.

    If you have any questions on working of TCA the I request, you to raise another thread with the exact part number so that the right experts can guide you on that device.

    Regards
    Varun