After reading for about 3 hours about the different problems and situations regarding very low and very high resistor values (source resistance / feedback resistance) with op-amps theoretically I understood all the mentioned facts.
But converting this knowledge into practically constructing a real schematic is still a problem to me. The datasheet of the op-amp used (AD4522 doesn't really go into explicit detail (or at least not into sufficiently transferred details for beginners).
On page 30 "USE OF LARGE SOURCE RESISTANCE" they go into detail with explicit values, but this is for a Unity Gain Follower circuit and not really a non-inverting amplifier circuit.
I tried to transfer this answer (How to choose resistor values in op-amps) to my case, but still struggling a lot.
My current thoughts are:
- Since "the basic op-amp load is the feedback resistor Rf" (Or does it only apply to inverting configurations?): @page6 "paramater@50V Vsupply" it mentions "Continuous Output Current" as 14mA. For safety reasons, let's assume continuous 10mA is okayish (am I right?). Therefore: R_f should be:
- R_f = V_output,max /I_cont. = 45V/10mA = 4,5 kΩ.
- Therefore with a gain of 37,5 => R_s = 123 Ω.
Am I right or is the calculation of the resistor values based on something completely different?