flat plate heatsinks

[Malcolm Reeves]

Hi,

I seem to remember that national had a app note on this with one of
those graphs you need a PhD to understand how to work. I can't seem
to find this online. Anyone know the URL or URLs for other sites with
flat plate heatsink formula / graphs.

TIA

--

....malcolm

Malcolm Reeves BSc CEng MIEE MIRSE, Full Circuit Ltd, Chippenham, UK
([email protected], [email protected] or [email protected]).
Design Service for Analogue/Digital H/W & S/W Railway Signalling and Power
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[Tweetldee]

Hi,

I seem to remember that national had a app note on this with one of
those graphs you need a PhD to understand how to work. I can't seem
to find this online. Anyone know the URL or URLs for other sites with
flat plate heatsink formula / graphs.

TIA

--

...malcolm

Malcolm Reeves

Seems that I remember such an application note in somebody's data book, but
can't find it quickly. Surf over to
http://www.aavidthermalloy.com/technical/index.shtml and read the documents
they have online.. Lots of good stuff.
There's also a pretty good page at
http://w1.859.telia.com/~u85920178/begin/heat-0.htm that you will want to
read.. It touches on just about every aspect of heatsinks and the theories
and technologies behind them. Also has a calculator there (Excel
spreadsheet) that will allow you to enter your dimensions and it calculates
the thermal resistance. Cool stuff...
--
Tweetldee
Tweetldee at att dot net (Just subsitute the appropriate characters in the
address)

Never take a laxative and a sleeping pill at the same time!!

 

[John Larkin]

There's also a pretty good page at
http://w1.859.telia.com/~u85920178/begin/heat-0.htm that you will want to
read.. It touches on just about every aspect of heatsinks and the theories
and technologies behind them. Also has a calculator there (Excel
spreadsheet) that will allow you to enter your dimensions and it calculates
the thermal resistance. Cool stuff...

That guy makes the very serious error of ignoring the thermal
resistance of the heatsink material itself. Even an infinitely large
box made of thin aluminum won't achieve 1.13 K/W for a single
transistor. And any seams in the box - like, if all 12 edges aren't
welded shut - will make things much worse.

John

 

[Rene Tschaggelar]

Hi,

I seem to remember that national had a app note on this with one of
those graphs you need a PhD to understand how to work. I can't seem
to find this online. Anyone know the URL or URLs for other sites with
flat plate heatsink formula / graphs.

The usual heatsink numbers have a bunch of conditions attached.
Such as unobstructed vertial mount. Free airflow from 40cm below
to 40cm above and such.


Rene