[sdiy] SSM2164 stability

[Neil Johnson]

Hi,

My guess...

(and it is *only* a guess)

...is that those values are those that give the very best performance
out of the 2164.

Now, we know (or at least can infer) from the datasheet that the input
stage is a little delicate.  So the series RC is needed to tame it.
But also, that 30k sets the drive impedance (assuming an ideal voltage
source, and an op-amp output is good enough in small signal).  So what
the 2164 input actually 'sees' is a 30k resistor in parallel with that
500R-560p series network.

Now with real component values we end up with 'close-enough' being a
33k input V-to-I resistor and some mix of 470/510 ohm resistor and
470p/560p capacitor (my own preference is 510R and 560p as I bought
bag-loads of those values specifically for 2164 projects :-).

Cheers,
Neil
-- 
http://www.njohnson.co.uk