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ISO7721: Is the 100 Mb data rate necessary for the Isolated CAN FD repeater reference design?

Part Number: ISO7721
Other Parts Discussed in Thread: ISO6721, ISO1044, ISO1042

I am referring to the following reference design: Isolated CAN FD Repeater Reference Design (Rev. A) (ti.com). The design supports a 2 Mb CAN data rate. However, the digital isolator used in the design, ISO7721, can support a data rate up to 100 Mb. Is there any particular reason the digital isolator data rate needs to be so much higher than the CAN transceivers data rate? I'm considering using a digital isolator with a lower data rate that's closer to the CAN transceiver, but curious if I'm missing something here that'd cause this to be a bad idea. 

  • Hello Logan,

    Thank you for your question and welcome to E2E! The ISO7721 can support speeds from 0-100Mbps. The ISO7721 is used in the reference design because it is from the newest digital isolator family (ISO77xx) and has TI's best isolation technology. The ISO6721 (data rate = 50Mbps) is an option If you do not need the speed of the ISO7721 and will still benefit from TI's latest isolation technology.

    Also TI has isolated CAN transceivers (ISO1042 and ISO1044) that may be useful to your application.

    Please follow up if you have more questions.

    Best,

    Andrew