The opamp is wired to make it as configurable as possible to either act as an inverter to get -5V or a double to act as 10V output or even to just buffer the output.
Not holding my breath for negative output if parts of the reference structure are tied to the substrate like in ADR1000.
There will likely be absolute maximum rating: BUF_GND = REF_GND ± small delta.
Replaced the 1uF alu with 1u5/25V tantalum one. Vin 15V.
dmm 10.000.016
w/ 100k 9.999.850V
166uV diff
![WTF? :wtf:](https://www.eevblog.com/forum/Smileys/default/wtf2.gif)
I would definitely check with a scope because it's an utter waste of time to debug an unstable circuit.
Then, measure voltages on all relevant pins and see if it really is the amp or something else that changes. And what happens at the inputs of the amp. If BUF_S is rock stable then yeah, wtf.
I agree that less than 1mΩ is perhaps too optimistic (and even if it's real, you won't see it without measuring on the pins directly), but more than 1Ω seems a bit much. What's the resistance of your wires, by the way? I think even that is still less than 1Ω.
@magic: where your ltspice model comes from?
I just installed the latest LTspice, ver 17.0.36, 32-bit.
BTW, I think this model may be transplantable to older releases. I was able to include it even in LTspice IV, but I haven't put the files in the library yet and I don't know how to include a symbol from the working directory,
so I couldn't put it on the schematic and see if it works. Sorted it, outcome: "Fatal Error: Singular matrix: check node u1:isense_m"
![Roll Eyes ::)](https://www.eevblog.com/forum/Smileys/default/rolleyes.gif)
edit
I see that the current version on the website is 17.0.35 and I'm pretty sure that this is what I downloaded before.
Nevertheless, help → about says that I'm on 17.0.36.
Can't explain this. Have fun
![Laughing :-DD](https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif)