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Date: Sun, 25 Oct 2015 01:42:31 +0200
From: "Gabriel Paubert (paubert AT iram DOT es) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
To: "Dave McGuire (mcguire AT neurotica DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
Subject: Re: [geda-user] Stable and low noise references
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On Sat, Oct 24, 2015 at 07:09:51PM -0400, Dave McGuire (mcguire AT neurotica DOT com) [via geda-user AT delorie DOT com] wrote:
> On 10/24/2015 06:54 PM, Gabriel Paubert (paubert AT iram DOT es) [via
> geda-user AT delorie DOT com] wrote:
> >>> This is becoming offtopic, but the LTZ1000A is, to my knowledge, still
> >>> the best reference available in terms of noise and long term stability,
> >>> and until a few years ago, I only used buried Zener references when I
> >>> needed high stability.
> >>
> >> It is. If you look at any of the tear downs people do of meters above
> >> 6 digits they are all using that reference or one made by LT custom
> >> for Fluke.
> > 
> > I was not aware of that, but this means that this device has cornered a
> > market from people accepting to pay for the performance and might not be
> > EOLed too quickly.
> 
>   This is very much an LT thing.  I think I can count the number of
> parts they've EOLed, ever, on one hand.  Maybe two, but not by much.

It is true that LT is one of the most conservative companies in this
respect, they apparently do not easily decide to EOL a given part.
That's one of the reasons for which I sometimes select LT over
otehr products from competitors.

However, they have EOLed a lot of metal can and ceramic packages, for 
example the LT1028 was originally available in metal can and ceramic DIP.
And these packages had at least a higher max operating Tj, so there is
no direct replacement.

I also just discovered that I was wrong about metal can, the LT1021 is
still available in TO-5; however some of the voltage/grade combinations 
have been obsoleted, and this includes all 7V versions.

    Gabriel