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ADuM3482  ground separation

Hi, I I'm looking for a suggestion how to separate isolated grounds...

My design requires 4 isolated lines, two IN, two OUT and GND connected to the DB-9 connector. Side 1 (FPGA) has a 1.8V level and the other side 2 (ext interface) is required 3.3V or optionally 5.0V level.

I found ADuM3482 to meet my design goals, however it appears that I need to have a separate isolated power source to supply side 2. That means addition of DC-DC transformer driver, transformer, diodes and LDO just to provide isolated  supply to side 2.

As I mentioned above, only Data and GND are required, it is not required to provide voltage to the DB-9 connector.

First of all, I would like to ask if what I described above regarding ADuM3482 ground connectivity is correct and if it is possible to separate Side1 GND and Side 2 GND just using a choke and supply side 2 with local 3.3V or 5.0V which are referenced to digital ground?

I'll appreciate any suggestions.

Thanks.

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  • Hello ARTS,

    If you separate GND1 and GND2 with a choke and reference the power for side 2 to side 1 then you'll lose the isolation that the ADuM3482 provides. ADI offers isolated DC/DC converters, and the ADuM5010 can provide the power required to operate the isolator up to its full rated speed. The ADuM3482 draws 10-11 mA on side 2 at 25 Mbps for 3.3 V or 5 V operation. The ADuM5010 provides minimum of 30 mA with 5 V output and minimum of 20 mA with 3.3 V output. It's offered in a small 20-lead SSOP package.

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  • Hello ARTS,

    If you separate GND1 and GND2 with a choke and reference the power for side 2 to side 1 then you'll lose the isolation that the ADuM3482 provides. ADI offers isolated DC/DC converters, and the ADuM5010 can provide the power required to operate the isolator up to its full rated speed. The ADuM3482 draws 10-11 mA on side 2 at 25 Mbps for 3.3 V or 5 V operation. The ADuM5010 provides minimum of 30 mA with 5 V output and minimum of 20 mA with 3.3 V output. It's offered in a small 20-lead SSOP package.

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