ADUM5020 and ADUM5028 for RS-485 Circuit

Hello,

I would like to use ADUM5020/ADUM5028 for a RS-485 circuit. With ADM2795E transceiever.
120Ohm Termination, 3.3V bus and 500kbit/s. 

Do you have an application note or example design about power calculations?
Thanks for any help.

  • Hi Hakan,

    I’ve added some details below on how to use the ADM2795E with the ADuM6028 DC-DC converter.

    The small size of the ADuM6028 makes this attractive in the space constrained applications. The ADuM6028 is suitable for 3.3V transceiver supply voltage on the secondary side. If you needs 5V transceiver supply, you could use ADuM6020, although this is a larger form factor. A circuit example with the ADuM6028 with a 3.3V output is shown below.

    I ran the power calculations, and below is the specific DC-DC converter I would recommend for fully loaded and point to point bus topologies. Power calculations show the max temperature and were worked out at the ADM2795E maximum datarate of 2.5Mbps.

    Isolation Rating

    VDDP supply voltage

    VISO supply voltage

    Recommended Isolated DC-DC Converter

    Maximum Temperature (Fully loaded bus)

    Maximum Temperature (Point to point, single 120ohm termination)

    5 kV

    5 V

    3.3 V

    ADuM6028-5BRIZ

    85⁰C

    105⁰C

    5 kV

    3.3 V

    3.3 V

    ADuM6028-3BRIZ

    105⁰C

    125⁰C

    5 kV

    5 V

    5 V

    ADuM6020-5BRIZ

    85⁰C

    105⁰C

    2.5 kV

    5 V

    3.3 V

    ADuM5028-5BRIZ

    85⁰C

    105⁰C

    2.5 kV

    3.3 V

    3.3 V

    ADuM5028-3BRIZ

    105⁰C

    125⁰C

    2.5 kV

    5 V

    5 V

    ADuM5020-5BRIZ

    85⁰C

    105⁰C

    Kind Regards,

    Neil