Hello Vortex-L participants,
First, I'd like to introduce myself, since this is my first time posting to
the list.
Thus far, I've only read the web archives sporadically, and have found the
most interesting discussion matters to be well over my head, since I have no
formal nuclear physics education, and have presumed I would have little to
add. My background is in electronic design engineering, mostly high-speed
digital systems.
I have skimmed a few recent threads discussing thermal modeling using SPICE
that David Roberson (and others?) has been posting about, and finally found
a point I might add.
There are limitations to using capacitive elements to represent thermal mass
with transient inputs, particularly with discontinuous input functions. In
addition, appropriate element sizing and granularity is important; too few
elements or the wrong size elements will see results diverge from real
responses.
I found one decent appnote that discusses some of these points in detail, as
applied to semiconductor packages:
www.onsemi.com/pub/Collateral/AND8218-D.PDF
If I find any more write-ups, I'll post them. It's been too long since I
was directly involved in SPICE thermal modeling, but I do recall a number of
warnings from experts about divergences, subtle and not.
Hope this helps,
Robert Ellefson
