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[SOLVED] EVAL-ADE9000-Shield what is C54 for? ?

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Jadeit

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I'm looking at the development board for the ADE9000 energy meter.

VBP and VBN are the inputs of the differential ADC for voltage measurement
In contrast to the recommended connection in the ADE9000 datasheet, there is a C 54 51pF coupling between VBP and VBN.
Can anyone explain to me what this capacitor is for and why it is good to use it?





C54.jpg
 

FvM

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Looking just at the net list, the 51 pF capacitors seem to have very little to no effect, because they are in parallel to effective 11 nF of C33 + C35. In the actual dev board, they may compensate for non ideal ground connection and series inductance of C33 + C35, but it's still questionable that they have any effect. If you copy the eval board to your design, you may keep an unpopulated cap position as option for stronger differential filtering if ever required.

The right place for your question is ADI EngineerZone, I think.
 

carpenter

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The right place for your question is ADI EngineerZone, I think.
I originally directed my question there.
Unfortunately, my sclerosis made it impossible for me.
I can't remember my login details :)
 

carpenter

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According to the engineer who designed the board, the capacitor is designed to suppress EMI interference. It can help pass EMI tests, but it largely depends on the component layout and the type of PCB.
--- Updated ---

According to the engineer who designed the board, the capacitor is designed to suppress EMI interference. It can help pass EMI tests, but it largely depends on the component layout and the type of PCB.
I want to use a two-layer PCB so I leave a capacitor with 47pF in the design, it can't always be fitted.
 

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