Suggestions for a dual 5V isolated power supply

Hi..

I am designing an arduino based 3-phase energy monitoring system around the ADE 7758 chip by analog devices.

The system requires two separate 5V supplies, one for the digital side including the MPU, LCD etc and the other for the ADE7758 analog side. The two parts of the system operate in galvanic isolation so that the AC mains side of the circuit is kept separate from the rest. All digital i/o between the two parts is done via ADUM1402 digital isolators.

I now have to design a suitable dual output 5V supply for the above with the two supplies also isolated.

The current requirements are small : about 20mA for one and less that 100mA for the other (MPU and lcd side).

I am looking for recommendations on how to best acheive the above.

Needless to say, that I wouldn't like to mount 2 transformers on the PCB mostly because of their size and weight.

Is there a way to achieve galvanic isolation between two DC supplies? ( something similar to what a ADUM1402 is doing above for signalling)?

Any suggestions welcome...

Dual secondary winding transformer? You can have a transformer with separate output windings, which would be galvanically separated.

GeronimoDK: Dual secondary winding transformer? You can have a transformer with separate output windings, which would be galvanically separated.

Thats true and it was one of my thoughts.

However to be truly safe, the transformer would have to have four separate coils on a U shape core otherwise the isolation between winding turns might not be sufficient. This is not a standard transformer and they tend to be expensive and bulky.

I'd suggest board mounted isolated DC-DC converter to say 8 or 9V, then a 5V linear regulator for the analog supply - this will give optimal analog performance and is simple and flexible. Such board-mount DC-DC converters are widely available in many voltage and power options, so could run direct from the digital 5V rail if you want.

MarkT:
I’d suggest board mounted isolated DC-DC converter to say 8 or 9V, then a 5V linear
regulator for the analog supply - this will give optimal analog performance and is simple
and flexible. Such board-mount DC-DC converters are widely available in many voltage and power
options, so could run direct from the digital 5V rail if you want.

Something like this ?