This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ISO1050: 2 ISO1050s and 1 isoSPI IC - How should I configure GND?

Part Number: ISO1050
Other Parts Discussed in Thread: ISO1044, ISO1042

Hello TI team,

my customer wants to design the circuit with 2 ISO1050s and 1 isoSPI IC.

1 ISO1050 is for communication with external device, another ISO 1050 is for debugging internally. it is used with isoSPI IC.

in this situation, How should I configure GND?

1. make separate GNDs all three output GND of the ICs

2. tie up GNDs of 2 ISO1050s, and make separate GND of isoSPI IC

3. make separate GNDs for 1 ISO1050 (for communicate externally), and tie up GNDs rest of 2 ICs(1 ISO1050 and isoSPI for debugging internally)

4. tie up all 3 output GNDs, but it is separated from main GND obviously.

actually we think no.3 is right.

please check this issue, and give me the right answer. Thanks.

Best regards,

Chase

  • Hi Chase,

    Thanks for reaching out. It would help better if you could share more details about the application and maybe a block diagram as well indicating how exactly all the isolators located. Alternatively, a complete schematic would also give us this information.

    I understand that one CAN device ISO1050 is used for communication to external devices. The other CAN ISO1050 and isoSPI device are used for debugging. Did you mean to say that both CAN and SPI interface are used in parallel to debug at the same time or are they given as an option allowing either CAN or SPI is used for debug?

    I am assuming the primary side of all three isolators has a common ground. Please see my inputs below regarding your questions,

    • If the secondary sides of isolators are not connected / interacting with each other then it doesn't matter whether they share a common ground or have a different ground. There shouldn't be any difference in performance.
    • If the secondary sides of these isolators are connecting to each other or are connected to the same system, then it is best to have their grounds connected together on secondary side. Like you mentioned in point (3), if ISO1050 and isoSPI are connecting to the same system on secondary side then they can have a common ground while the other ISO1050 that is connecting to external devices can have a separate ground. Hence, point (3) seems perfect for this scenario.

    ISO1050 is one of very old ISOCAN devices, I would recommend customer to consider our newer ISOCAN devices that offer significantly better performance with respect to both isolation and CAN interface. Based on customer isolation requirements, they could either choose ISO1042 or ISO1044.

    Let me know if you have any questions, thanks.

    Regards,
    Koteshwar Rao