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ISO7742: iso7742 for 422 interface

Sammi Shang
Expert 4450 points
Part Number: ISO7742
Other Parts Discussed in Thread: ISO7721, ISO1452, ISO1432, SN6505B, ISOW7821

Dear team,

I want to check if connect ISO7742 with the 4 wire of 422 is right or not? I attached the picture. Customer will connect ISO7742 between 422(ABZY) and other processor.

Thanks.

Best regards,

Sammi

  • 0
    TI__Mastermind 49895 points

    Hi Sammi,

    I see that MAX13087E is a non-isolated RS-422/RS-485 transceiver. Did you mean to ask if customer can use ISO77xx devices to add isolation between processor and MAX13087E? The answer is yes, customer can use ISO7721 to connect between processor and MAX13087E. I suggest ISO7721 because only 2-channels will be sufficient to isolate TXD and RXD pins.

    Alternatively, customer can use TI's isolated RS-485/RS-422 transceiver like ISO14xx which includes both isolation and RS-422 transceiver in one device instead of two separate devices. MAX13087E supports 16Mbps full duplex operation. Based on whether customer indeed needs 16Mbps datarate or lower, customer can either choose ISO1432 (12Mbps) or ISO1452 (50Mpbs).

    The above suggested devices are for isolating data channels, customer will have to isolate power as well to be able to correctly achieve RS-422 isolation. Customer may already have isolated power supply available but if he doesn't then you can use either of the below isolated power supply solutions.

    1. SN6505B - Discrete isolated power supply solution, lower cost but large solution size including an external transformer.
    2. ISOW7821 - Integrated power supply, a single device with very small solution size which also integrates the power transformer inside device.

    Let me know if you have any questions, thank you..

    Regards,
    Koteshwar Rao