Question
I'm in charge redesigning a product based on a ADE7753. Somewhere in our design
specifications is written that AGND and V2N pins of the ADE7753 must be on the
same voltage level. The engineer that wrote this is not around and there is no
further explanation in our specs about that.
I want to be sure this is something mandatory (I didn't find anything about
this point in the ADE7753 datasheet) because designing in that way makes no
insulation between the line to be monitored (230V mains power supply) and the
ADE7753 (and all the electronic components). So I'll be glad if you can help
with that point, telling me if this is something mandatory and why?
Answer
For a single phase application please take a look at the attached PPT. The V2N
pin must be connected to ground because the ground of the meter is created by
one pole of the shunt. As ADE7753 ADCs do not accept common mode, V2N and V1N
must be connected to AGND.
The isolation must be done and there are two places for it: or between MCU and
ADE7753, or between MCU and the human interface.