El Cajon, CA
USA
-Original Message-
From: John Shinn [mailto:jmsh...@pacbell.net]
Sent: Tuesday, October 09, 2012 10:25 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: Re: [PSES] thermal resistance - K versus C
Naftali is correct in that Kelvin is an extension of °C, only offset so that
0
glad we didn’t need a heatsink or, worse still, forced air cooling. Things
get a little more complicated… But not too much.
Hope this helps.
T
- Original Message -
From: McInturff, Gary
Sent: 10/09/12 09:28 PM
To: EMC-PSTC@LISTSERV.IEEE.ORG
Subject: [PSES] thermal resistance - K versus C
Thought I knew what I was doing, obviously I don't
I have a device with a thermal resistance ThetaJA (J-P in this documentation).
It's for SMT CHIP LED the specified value is 400C/W. for a plastic package that
seems about right. I am looking at another LED but it lists ThetaJA as
400K/W.
Gary-
First principle: Heat flows from hot to cold, just like water runs down
hill. You need to use a pump (a heat pump for heat, or a water pump for
water) to make it flow up hill. Just as it takes energy input (into a
pump) to make water flow up hill, it also takes energy input to make heat
Hi Gary,
Theta JA is a differential, not an absolute temperature. Many manufacturers use
Kelvin when describing temperature differentials and Celsius when describing
actual temperatures. However, for Theta JA, it doesn't matter whether the
vendor talks about Kelvin or Celsius; they are only
Hello Gary,
In this relationship 1 K/W equals 1 C/W.
As one example, see http://www.diffen.com/difference/Celsius_vs_Kelvin
Br.
Helge Knudsen
Denmark
From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of McInturff,
Gary
Sent: 9. oktober 2012 22:29
To:
K or C are (almost) identical, just the starting point is different: C
starts @ 0 (freezing temperature for distilled water at sea level
pressure, i.e., 1 atmosphere), and defines 100 as boiling of same
conditions.
K is the same as C, but is off-set by 273 (i.e., 0 K is -273 C, so 100
C is 373 K).
Naftali is correct in that Kelvin is an extension of °C, only offset so that
0 Kelvin is at
absolute zero, or -273.15 °C. When referring to a Delta-T, the number is
the same
whether in Kelvin or °C. Be aware that the specs noted are Delta-T/Watt,
not actual temperatures.
Also, Theta JS is
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