Dear forum,
I have done some experiments trying to measure small currents. I have posted here in the past
http://e2e.ti.com/support/amplifiers/precision_amplifiers/f/14/t/366.aspx.
Today trying to do the same thing but with smaller output range like +/-2V, I supplied the IVC102 with +/-5 V.
Back then everything worked like a charm, but now the transfer function is out of control.
Here is a small outline of settings (similar to the past):
Cint =100pF, Tint=1us and Vout = -195,76 x i +178
instead of V = -1.002 * i + 0.006 (in the past).
I have even made a second pcb trying to leave out leakage and stray capacitance, as it looks like there is a ~2pF in series with the internal Cint.
So I found my old project that worked. And I got similar ugly results...
Then I rechecked and saw at datasheet's page 2, where it says minimum negative power supply -10V and maximum -18V.
Oh my god!
Is this correct ?
and could it be the reason for my problems and lots of hours troubleshooting?
Thank you all a priori