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Question about Modification in the Circuit of  ADE7953 Evaluation Board

Question asked by mamech on Aug 26, 2015
Latest reply on Oct 17, 2015 by mamech

Hello

 

We are designing a prototype for a product based on  ADE7953 IC, and we try to make its interfacing circuit based on ADE7953 Evaluation Board. But there are some questions that we have and we want to be sure that we are on the right track.

 

1) regarding the voltage channel in ADE7953, We need to have the ability of swapping voltage (line and neutral). Our product must be able to deal with case when the end user reverses the neutral and line. I have read in 2 threads in engineering zone that suggested to have attenuation networks for voltage on both line and neutral, so according to my understanding the correct circuit will be the same as the attached photo (photo named Voltage measurement circuit).

my questions about this point:

              A- Is the attached circuit correct?

              B- the purpose for attenuation network is to make voltage divider, so is n't it strange to make voltage dividers on both of the line

                  and neutral with the same values used when attenuating the line only? from my point of view, the resistors values in the

                  second case need to be half of resistors values when attenuating the line only.

              C- When attenuating the line and the neutral, will it cause any problem to use isolated flyback switched mode power supply for

                   supplying the ADE7953 ? will this cause any problems regarding correct grounding?

 

2) regarding the digital isolator that you are using in your design to isolate the 14 I/Os of microcontroller and ADE7953, it is problematic for us to use same three adum1401crwz and one adum1250arz due to the high cost (they will add cost more than 7.74 sterling pound only for isolation part) . this will raise the cost of our product much or will reduce our profit.

my questions about this point:

             A- I searched for other alternatives, and I found that we can use 2 x ICs adum3151arsz  as it is 7 channel, so only 2 ics of it will

                 solve the problem and will enable us to make isolation for lower cost (the 2 ics will cost around 3.26 sterling pounds). is this

                 solution is also valid technically?

             B- Our Application is not critical regarding communication speed (lower than 3.5 Mbps), so I wonder are there any suitable low

                 cost optocouplers that can do the job of isolation? any suggestions for any optocouplers that can do the job?

 

thanks for help

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