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ISO6742: Which one is the best selection of ISO6742/ISO6721/ISO6721R to connect with THVD1500?

Part Number: ISO6742
Other Parts Discussed in Thread: ISO6721, , THVD1500, ISO6721R, ISO6731, ISO6741, ISO1500, ISO1430, ISO1450, ISO1410

Hi experts,

My customer want to realize isolated RS485 through using ISO6742 and THVD1500. But, from my opinion, the ISO6721 or ISO6721R is enough for THVD1500.  So, I am confused if I miss something importantly.

By the way, What is difference between ISO6721 and ISO6721R?

Thanks and BR,

Gordon

  • Hi Gordon,

    Thanks for reaching out.

    Since THVD1500 is a half-duplex device, customer would also have to be able to disable the driver so that they can receive data from other nodes on the bus. If you do not disable the driver, it will hold the bus busy and nobody else will be able to transmit. Hence, at least 3-channels are needed to be interfaced to THVD1500 and hence need 3-channels of isolation.

    If customer only wants to control DE or control DE & RE\ tied together, then ISO6731 would be the suitable device. If customer likes to control both DE and RE\ separately, then they would require ISO6741.

    Alternatively, you could also recommend customer to use ISO1500 which integrates digital isolation and RS-485 to a single device into a very small package. If higher isolation ratings or larger creepage needed then ISO1410/ISO1430/ISO1450 would be a suitable option.

    By the way, What is difference between ISO6721 and ISO6721R?

    The two devices have the same number of channels in similar directions. They only difference in the position of those channels. ISO6721R is developed to enable P2P replacement for some existing competition devices which follow such pin-out. Otherwise, there is no difference between the two devices.

    Let me know if you have any other questions, thanks.


    Regards,
    Koteshwar Rao

  • Hi Rao,

    Thanks for your real quick reply. Your explain is very clear and helpful for me. thanks!

    BR,

    Gordon