ADE 7953 design consideration

Hello,

I am working with ADE 7953 in an application where I need to measure single phase current and voltage. I am in the phase of designing the PCB for ADE 7953 and would like to ask some basic questions related to the design. My application consists of Atmel SAM4S uC which operates at 3.3V for this I will need a power supply which will also be used for powering up ADE 7953. I would like to ask, whether I need an isolated power supply for ADE 7953 or can I use the same one that I will use for uC? Also if I use the same supply would it be okay to use the same GND for both? Is there an isolation inside ADE 7953 which separates the high voltage AC measurement side of the device from the digital outputs and power supply side? I have gone through the Application Note AN-639 but still have these doubts. If someone could help me in this matter it would be much appreciated.

Regards,

Owais.

  • Hi Owais

    Technically, ADE7953 and the MCU can be on the same ground. So, the same power supply can be used. But ADE7953 doesn't have any isolation (from the high-voltage) within it. So, if the MCU is connected to any communication blocks like RS485 or a personal computer, then an isolation barrier must be created either between ADE7953 and the MCU or between the MCU and the block that needs to be protected. In some special cases, based on compliance requirements to some standards, two levels of isolation might be required.

    Also, if the power supply ground is tied to earth potential, then connecting it to the phase wire (which is the ground of the ADE7953) will cause issues. So, in cases like that, isolated power supply should be used. On a similar note, if the power supply doesn't allow 220V/110V (phase wire) to be treated as the ground potential, then suitable changes need to be made in the power supply design.

    Reviewing any other safety or isolation requirements to be met (based on standards that you need to adhere to), is very useful before finalizing the design. Let me know if you have any further questions!

    Regards

    hmani

  • Hello hmani,

    Thank you for your response, will keep these recommendations into consideration during the design. Could you also tell me if there is a list of components or recommendations for the test circuit shown in the data sheet as well as for the components required for Anti-aliasing and Attenuation network?

    Regards,

    Owais.

  • Hi Owais

    I cannot recommend any particular component manufacturer. But you can browse through the components used in the ADE7953 evaluation board (attached) for reference.

    Regards

    hmani

    ADE7953_Evaluation_Board_BOM.xls
  • Hello hmani,

    Thanks again for sharing the Evaluation Board BOM, it will most definitely help a lot in designing. I would like to ask you about the concept of connecting the phase wire to the ground of ADE 7953, it is a bit confusing to me as to why this is done and what advantages does this have over connecting the neutral to the ground? Please explain this to me or refer to some material where this is described in detail. Thanking you in anticipation.

    Regards,

    Owais.

  • Hi Owais

    If shunt current sensor is used in the application (which is most often the case in single-phase metering applications), then grounding neutral will mean there will be close to 110V/220V between AGND and the current input pins. This is unacceptable. Hence, we treat the phase wire as the ground reference for the ADE7953 IC.

    Regards

    hmani