Sv: [sdiy] Interesting Pease column in ED issue 50-14 (July 8,2002)

[cfmd at swipnet.se]

>   Wherein Bob laments about building an analog multipler with the 
> "obsolete" LM13600, is told the LM13700 is still made by NatSemi, and 
> proceeds to schem one up for the article (by drawing over top some 
> appnote, heh heh).
> 
>   I think I will write him and ask *why* the LM13600 is obsolete.  I won't
> let him get away with the answer "because we have the LM13700" because he
> thought it was obsolete too.  Obsolete, to me, means something is replaced
> by a better performing part.  What exactly is the better OTA that NatSemi
> offers that makes the LM13600/13700 'obsolete?'
> 
>   Heh, I think I'll tell him that JRC and Philips/Signetics/whoever owns 
> them now make the FRC13600, 13700 and NE5517... ;)

Well, one reason to clean out older designs is simply that Semi-houses change
their processes, and when they do they have to remap the design. Thus, unless they maintain the design they will eventually not be able to make it anymore.

Not that they change processes in a very high speed, but if you have a design of the age of 20-30 years, it is bound to have seen a few remappings in its day. For instance, the 741s of today are most probably much better as the freshbacked when it was originally introduced. Not that the actual design has been improved, but moved to better controled processes.

So, "obsolete" does not really mean the same thing, it is just "chips we don't want to make anymore". This is basically a buissness decission. If you make some chips popular, they will survive longer. Others will die out for one reason or another. So, in one sense will Bob's view allways be tainted by the place he looks and the views of opinion that rules there... and on some questions he will never be a good source for good answers, since he just has the wrong end of the stick. He do have a good point in many other cases thought, no question about that.

That is not a beg to bye more 741s, but sometimes I am happy that they are still around. (Please, do not toss me 741-replacement tips!)

Cheers,
Magnus - how do not even homebrew analog ICs

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