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AD8436 current meter

Question asked by Jest62 on Dec 12, 2012
Latest reply on Dec 12, 2012 by jstaley

Hello,

 

Working on a project, where we have to measure currents up to 25Amps on pure sine wave voltage. For this we chose CKSR-15 from LEM. With two primary turns, it is working right between 0A and 25,5A as we need it. For RMS to DC conversion we are going to use AD8436 and here I need schematic approval (I am not strong in OpAmps so help is more than welcome ).

 

Since current sensor's output is 2,125V at 25,5Amps what comes to some 1,502V in RMS, it would be good to have signal amplified x2 – my ADC reference is 3V3. 

 

Here I have first question: should I amplify signal at the input or at the output?

 

In attachment you can find my schematics for which I think it will do 2x amplify at the input together with table of all inputs and outputs. Is this, as it is OK? Will it work as I expect? For C at CAVG I know, it is not orinted as it should be - bug in my schematic...

 

Thank you for all support and best regards,

Andrej

CKSR-15 to AD8436.jpg

P.S. Data sheet for AD8346 is full of errors - especially for avaluation board used in single supply mode...

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