I got a problem with AMP02 (8 pin package) or AD620. Both have the same pinout.
I connected them at the following circuit:
The gain is 100, and there is a voltage divider of 100.
Jumper J1 on the left is closed.
I connected a 9V battery to the input (BT1). I measure 9V at the output. I reversed the polarity of the 9V battery at the input. ) get -8.9V at the output.
The amplifier is powered from a linear, floating +/-15V power supply. The DVM is floating as well.
Now I removed J1 and connected J2 J2 connects a 9V battery to the input (i.e. common mode voltage of 9V). I get only +5V at the output!
Now I removed JP1 and JP2 and connected JP3 which is also a 9V battery but with reveresed polarity (- at the input and + at GND). I got -1.06V at the output.
I wonder what did I do wrong? The datasheet specifies a common mode voltage of 11V!
I disconnected all 3 jumpers on the left and did the same experiment with the jumpers on the right (which are connected to pin #2 of the instrumentation amplifier).
When I connect 0V - good results. When I connect +9V offset - again - measure around 5V. When I connect -9V (JP3 ) - again weired results - about -2V !
I tried the same with AD620 and AMP02. Both provide the same results. Both are original chips bought from Analog Devices USA.
Is there any flow in my design?
See fig 5-3 in the 3rd edition of the InAmp guide.
Also use the InAmp diamond plot tool on our website.