[sdiy] How to Affix Thermistor to LM394

[ChristianH]

Well, Harry's comment made me remember where I read it.

The National LM3911 data sheet says "It should be mentioned that the
LM3911 die is on the base of the package and therefore coupling to the
base is preferable."

However, it's questionable if this is true in general. Maybe it *does*
pertain to the LM3911 only (a temperature sensor, now obsolete, related
to LM35). But then, maybe it just has been pointed out there, because
temperature coupling is particularly important in this case.

And, it not even indicates if it applies to DIP and/or TO package (3911
was available in both). 
AFAIK, TOs are built on a base carrier, and the metal hat is just put
over it, which would make the top inferior for coupling. (And hasn't at
least the famous 726 got some protrusion on the TO base for easy thermal
coupling? It's been some 25 years that I last used one.)

Christian



On Thu, 7 Sep 2006 15:01:14 -0700 (PDT) Harry Bissell Jr
<harrybissell at prodigy.net> wrote:

> In many cases attaching the thermistor to the
> lead frame (pins) might be better than to the
> plastic top.
> 
> Some app notes for temperature sensors like the LM35
> suggest this might be so...
> 
> H^) harry   (epoxy ;^)
> 
> --- Ken Stone <sasami at hotkey.net.au> wrote:
> 
> > To the top. It's stuck on top of the metal carrier
> > that forms the pins, and
> > that is usually cast centrally within the package,
> > thus the die is above the
> > half-way point.
> > 
> > Ken
> > 
> > 
> > >> Isn't the chip inside located more to the DIP's
> > bottom anyway?
> > >> Not too sure, but I seem to remember something
> > like that.
> > >>
> > >> Christian