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Problems in AD620

Question asked by shreelokhande on Oct 23, 2011
Latest reply on Oct 31, 2011 by ScottH

Hello all,

 

I have designed a circuit using AD620 putting in unity gain and giving i/p as  0V - 10V  with supply +15V and -15V and ref = 0V (GND).

In fig2 m dividing 400V to 10V and feeding it to AD620.

 

When I test these channels separately the o/p is OK.

But when I simultaniously swiched ON both inputs The AD620 in fig 1 shows 1.2V increament in its o/p irrespective of the i/p.

When I swiched of the 400V i/p the o/p of the AD620 in fig 1(upper one) came back to original.

As I understood from the datasheet is the ref pin can be given to GND and did the same in both the cases.

There are 4 channels of each of these ckts on my board and I have given same GND to all ref pins of AD620.

 

Please suggest me the changes I need to do so that the variations on one channel should not affect the other channel.

analog_isolator1.bmp

 

Thanks and Regards,

 

Shrikant.

 

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