Hello Klauss, my OPAMP model is as shown bellow,LTspice is not allowing me to simulate its model so i used an alternative model just to simulate the principle,and see the transfer function in action.
I need to have this -3 Volts on the output side (its on the MAX 4231 original circuit) as shown bellow.
My circuit has two outputs
You said i should disregard R3 and R4 So V_plus=Vnon_inv=0.5v
So V_minus=0.5v also
so the current threw R1 is I_R1=0.5/R1 which is also the current that flows threw R2
0.5/R1=(Vout-0.5)/R2
Because R1=R2 Vout=1V which matches the simulation.
I=((1--3)/600)=1/150
Vout2=1-500*I=1-500*6.66*10^-3=-2.33V
which also matches to the simulation.
but in the the MAX4231 i also have the option of SHDN
So if i understand the data sheet bellow correctly when SHDN pin is 0V then the OPAMP output is GND and we have voltage divider between 0 and -3 instead of 1 and -3?
correct?