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My current system:-

I'm working on a electricity metering system ,

I'm using shunt resistor configured in high side mode (a current sensor ) ,

I'm also using ADE7755 measuring chip ,

A schematic of the current circuit :-

enter image description here

A higher resolution schematic here

The problem:- When connecting the circuit as shown in the above schematic , R1, R2 , R3 & R4 blow up with some fire .

This isn't the first time happens , it happened before 3 times .

My initial guess it's that Analog & Digital ground are connected some how ..

I'm ready for any questions to clear the problem , thanks .

UPDATE#1 :-

I connected the PIN AGND in ADE 7755 chip to the Digital ground

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    \$\begingroup\$ What's the idea of posting an 11 Mpixel BMP image for a schematic? If you would use the PNG format it would be less than 100 kB, so you wouldn't need the ZIP. And you can easily scale it down by 75 %, without any concessions to readability. I edited the link. \$\endgroup\$
    – stevenvh
    Aug 25, 2012 at 18:19
  • \$\begingroup\$ @stevenvh for ppl who need zoom (like me :D ) thanks =) \$\endgroup\$
    – xsari3x
    Aug 25, 2012 at 18:24
  • \$\begingroup\$ I think you can do other things for better readability than going to huge image sizes. For instance there's a line running through the values of R3 and R4. Wait until Olin sees this :-). \$\endgroup\$
    – stevenvh
    Aug 25, 2012 at 18:30

1 Answer 1

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If you look closely at the datasheet, you'll see that it plainly says the maximum signal you can apply to the amplifier inputs with respect to analog ground is +/- 1V (+/- 6V over voltage tolerance).

Your high-side current transducer is going to put a lot more common-mode stress than that on those pins, hence the blow-ups.

Consider a low-side sensor or an isolated transducer like a current transformer that can be referenced to the IC return.

Be safe - playing with the mains can be lethal. (I'm glad to see a fuse in your circuit!)

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