[sdiy] [OT] LM13700 spotted in commercial product of big Manufacturer

Roman Sowa modular at go2.pl
Mon May 16 08:19:21 CEST 2022

W dniu 2022-05-15 o 13:04, mskala at northcoastsynthesis.com pisze:
> The LM13700N, meaning the DIP version, certainly can be discontinued
> because it already has been.

just like thousands of DIP versions of other chips. A lot of chips ever 
appeared starting from SOIC, ditching DIP from the start. It's not about 
LM13700 in particular, but DIP.

> specifically the DIP version that was discontinued by TI, and I think it's
> unlikely that Fender is actually using the DIP version.

> The LM13700 - no suffix, meaning the silicon die that might be packaged
> some other way than DIP - is a different question.  That is a popular IC
> with a big market, and it would be harder for TI to discontinue all
> versions of it than to discontinue just the DIP version.
that's what I was talking about. If there's demand, and there is, 
there's supply. I wasn't specifically mentioning DIP version, as for me 
DIP died 25 years ago and I don't miss it.
> But they still could!  Remember that one important reason the LM13700 is
> so popular now is because it is pretty much the last OTA available.  Many
> people using the LM13700 would really prefer to use the CA3080, CA3280, a
> Roland custom chip, or similar... but those are all gone.  Being the last
> one available improves its marketability, but the reasons why the others
> were discontinued do also apply to the LM13700.
Like many already mentioned, there are quite a few alternatives. Not 
direct replacements, but with better specs. I mean many of VCAs 
available right now of course.
We might as well wonder why Norton opamps are still araound, or 
programmable opamps like LM4250. I think the popularity and availability 
of LM13700 is that is dirt cheap.

> package does not bode well for it.  If they really thought this was a chip
> with a strong market for the long term, they would be introducing newer
> packages for it.
I'm not an expert in IC design, but clearly such an old design is 
possibly too large and would not fit in WSON package. I don't know any 
old IC that went down in scale below SOIC, unless it's totally 
redesigned few times like TL0xx or logic families.

> So I don't think the LM13700 is secure forever, even though it's probably
> secure enough for the next few years that Fender can reasonably use it in
> a new design; provided they're not using the DIP version, which is
> already discontinued.
There are still opamps being made in bipolar process and they are made 
in milions. I don't think anybody would close such a fab just because 
it's old process. The staff there has changed many times already, and 
knowing how corporations work today it's clear that using all the 
equipment is based solely on written procedures, and not any human 
memory. All those opamps are 40 years old if not older and they still 
sell in milions.

> TL07x is an interesting case.  Go to the TI Web page for the TL074 and
> there's a big notice on it saying "A newer version of this product is
> available," pointing at the TL074H.  Read the data sheet for the TL07x
nearly every IC page at TI website suggests newer version or equivalent.
We have talked already a year ago here about the H series and why it 
didn't get it's own new number. Nevertheless the old TL072C is in stock 
in impressive quantity, possibly not planned to dissapear in years.
> sections of the data sheet (sections 3 and 8) are devoted to telling
> readers that the TL07xH is better than the other versions.
well it is better in many ways, as it's basically different opamp.
> Notwithstanding the similar model number, it seems clear that the TL07xH
> is a completely different product, with a much newer design, and TI is
> strongly encouraging you to use it instead of the traditional TL07x.
exactly, based on unbeatable marketing success of TL07x that's easy way 
to promote new opamp


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