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From: Ben Mack
Subject: Re: Thermal effects of potting compound?
Date: Wed, 23 Oct 2002 10:00:12 +0100
Organization: Watchfront Electronics
Reply-To: Ben Mack
NNTP-Posting-Host: zaphod.watchfront.co.uk (220.127.116.11)
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In article <firstname.lastname@example.org>, Ge0
>Under worse case conditions this device would be forced to dissipate
>1.8W for approximately 500ms until the safety shutoff mechanism takes
>place. Under worse case nominal operating conditions it would be
>forced to dissipate 816mW for 8 seconds on, then 14 seconds off. This
>duty cycle would repeat for 2 minutes 30 seconds and then the unit
>would complete it cycle and shut off.
The thermal mass of the potting compound is your friend here - no need
to dissipate all the heat, just store it up in the potting compound and
dissipate it later
I'd suggest doing all the maths, then building one with a thermocouple
buried next to the MOSFET and see what happens.
It sounds like a winner
Ben Mack mailto:email@example.com
Watchfront Electronics http://www.watchfront.co.uk/
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