SA571 and SA572 LTSpice models

[hgamal]

Does anybody have the LTSpice models for SA571 and SA572?

I've searched on the web, and I've got no results.

[Eb7+9]

you won't find spice models for those IC's ...
even for the first release

IMO the only realistic thing you can do here is go thru the original Signetics product guides and fill in the blanks starting from the simplified figures of the three main circuit blocks provided there (the gain block and rectifier are the same for the 570, 571 and 572) ...

but if you don't know std analog VLSI design techniques you likely won't understand where the simplifications are (nor fully why they were made) and so won't be able to fill in the parts that were left out ... those data sheets were written with design engineers in mind

just to give an idea of the work involved
it took me over a year and prob close to 100 sims to get the whole thing sussed ...

once there you can go other places with the original circuit blocks (... !!)

for example, if you replace the deltaG gain block by an OTA and the rectifier by HW cheese and you've got the THUMBS automatic-level-control circuit to play with, and evaluate //

I did the 570 in TINA-TI ... starting with individual sections
and eventually running full system sims using guitar phrase samples

it's doable, the same way the EMS synthi is doable
at least in TINA-TI ... I don't know about LT-spice limits

[Rob Strand]

There *is* enough info in the Philips app notes and datasheet to piece together the main blocks in terms of a transistor based circuit.   It's probably easier to forget it and make a generic control source using a spice controlled source.   It depends what aspects you want to emulate.  Three areas: opamp, gain element rectifier.
- opamp clipping  --> will need some attention to details
- subtle behaviour of the rectifiers -->  copy Philips rectifier circuit and tweak
- bias currents and so it works with the external 10M resistors  -->  better off just hacking the rectifier or VCA to have a minimum gain
- distortion nulling - forget it, spice parts are balanced.
- feedthough - in practice the feed through is fairly consistent but not so simple to emulate over the full control range
- noise.   Not so easy.  I suspect noise just faking it with a noisy resistor would do base-line noise.
- finer points of noise from the reference.   The chip has some weird behavior here.  I know it's there but how to emulate it ... hard work.