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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum (src_forum@alionscience.com )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

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Original Message:

Posted by:C.P. Chuah (c.p.chuah@sheffield.ac.uk )
Organization:University of Sheffield
Date posted: Wed Nov 6 8:24:27 US/Eastern 2002
Subject: PRISM demo
Message:
I have another question regarding the PRISM software. Can someone tell me what is dormant temperature? Why is the overstress message only comes up when the temperature is over 200 degrees when the junction temperature should not exceed 150 degrees. Is this a fair comparison ? Why is also the thera-JA must be in the range of 1-500 whereas the data available from most manufacturers states a theta-JA of less than 1.


Reply:

Subject: PRISM Questions
Reply Posted by: Norman B. Fuqua (nfuqua@alionscience.com )
Organization: RAC
Date Posted: Thu Nov 21 11:19:18 US/Eastern 2002
Message:
The “Dormant” temperature is typically the non-operating or normal storage temperature for the equipment. The 200 degree value is a generalized warning cutoff point, not an absolute number. To be totally accurate it would have to be different for each device. 200 degrees was selected as a compromise because some discreet power devices can safely go that high. Perhaps 500 is too high a cutoff for the theta-JA, we will reexamine that value.


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