The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: firstname.lastname@example.org (Bob Wilson)
Subject: Re: Question about linear derating factor for MOSFETs
Date: Mon, 11 Nov 2002 04:38:23 -0000
Organization: Your Organization
X-Newsreader: WinVN 0.99.9 (Released Version) (x86 32bit)
References: <email@example.com> <firstname.lastname@example.org>
In article <email@example.com>,
>>>> ** No, the case temp will need to be measured. It will have a
>>>>significant thermal loss depending on mounting arrangement and the
>>>>temp of the heatsink immediately under the device pack is the one that
>Ahh...of course, makes sense now. Seems like I could derive the case
>temp knowing the load, the heat sink temp (under load), the calculated
>junction temp, and the thermal resistances of the device (theta-jc)
>and the thermal grease?
>Otherwise, the heat sinks I'm considering have a hole drilled to
>directly underneath the center of the mounting location for the
>MOSFET. I can use that for a thermistor. Actual temperature
>measurement, for me, is the best way to verify performance for this
>situation. But I'd prefer to get a decent idea of the temperatures
>beforehand though...those bonded-fin heat sinks (Melcor) are very
>>>> ** I suspect it is going to be difficult to safely achieve 350 watts
>>>>dissipation from one device unless liquid cooling is used.
>I agree. I forgot to mention that this example was only to see if I
>understood the math. I'm limiting the load to 125-150 watts.
Still far to high unless you do something to reduce the thermal resistance
of your case to heatsink interface. See my earlier post.
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup