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ISO7221A: 500kbps CAN isolation

Satoshi
Guru 19485 points
Part Number: ISO7221A
Other Parts Discussed in Thread: ISO7731, ISO7731-Q1

Can ISO7221A use for 500kbps CAN interface?

I think that ISO7221A can't use this interface because ISO7221 can't keep up with CAN loopback. (require 1Mbps + margin for propagation delay)

And propagation delay: 280ns_min is large.

Please let me confirm that above thinking is correct or not.

If there the other careful point for isolated CAN interface, please let me know together.

Best regards,

Satoshi

  • 0
    TI__Expert 6195 points

    Hi Satoshi, 

    I agree with you that ISO7221A would not be a good choice for 500kbps CAN interface. When considering propagation delay, one should consider the maximum propagation delay spec to account for voltage, temperature, and part to part variation. The ISO7221A has a maximum propagation delay of 480ns. This is due to the fact that the A-option, B-option, and C-option devices have TTL input thresholds and a noise filter at the input that prevents transient pulses from being passed to the output of the device

    There are a couple of recommendations I can make for you for isolated CAN interface. If you prefer a discrete solution you could check out this Automotive Reinforced Isolation CAN Reference Design that uses the TCAN1042 chip and the ISO7731-Q1. The ISO7731 is very similar to the ISO7221A, but is using our newest and best isolation technology. 

    For an integrated solution I would consider the ISO1050 - an isolated CAN transceiver all in one that is capable of communicating 500kbps. 

    We also have a new device coming out soon, the ISO1042, which is our latest and greatest isolated CAN transciever. There is a preliminary datasheet online and you can sample it now.  

    Please let me know if that answered your question! And thanks for posting this question!

    Best regards, 

    Dan