Acording to various post on the forum to prevent that the phase and neutral channel inputs get switched around we should do a voltage divider on VP(phase) and VN (Neutral) similar to the on on the schematic.
If we were to use a single-ended configuration then the neutral line would be directly connected to GND, when in differential mode how should we connect GND.
Another question is related to DGND e AGND:
In AN-639 says "All the other circuitry, such as current sensor circuit, ........must be grounded to the digital plane of the system.", however doesnt this introduce alot of noise in our signal conditioning.The majority of projects with this IC connects the corrent reading to AGND.
If possible could you give your opinion on the prototype PCB that we design,more expecifialy the AGND and DGND planes and the schematic on the pdf file
Thank you in Advance ,
Hi, first off, the neutral line is not the one connected to ground, it is the phase. Please see this figure:
In singe phase metering, the phase should be the one referenced to the ground of the chip, ADE7953 is a single phase chip. Neutral ground is for three phase configuration. This allows the grounding location be with the current sensor and not after the load.
The position of the voltage divider is across the neutral and the phase as it is a differential pin. However your configuration is still okay, because you will have to reference your ground to the phase.
The analog grounds should be tied with the analog ground plane, the digital grounds on the digital plane, vias will interconnect the two.
Hope this helps.
Thanks aheredia, for your help.
When you say that we should connect 220V to GND my first though is "short-circuit", since we need to do measures in the board with an oscilloscope, so if we have the circuit at line voltage, there's a high personal risk, could we prevent this with a isolation transformer during testing phase.
Our current reading is a magnetic sensor that needs analog signal conditioning, for that we use a instrumentation amplifier, if we were to connect Phase to GND then the amplifier and the current sensor will also be at 220V.
For testing purposes the power will be provided by a lab PSU (TENMA 72-8690), and we probably can't use the 220V for reference.
All this conditions lead me to think that we can't reference our sound to the phase.