eally? 1.25W in an SOT23 pkg?  For how long?

Not as crazy as you might think, given optimal conditions, a =

good leadframe,
and a totally unrealistic room-temperature ambient:

http://www.zetex.com/3.0/pdf/ZXTP25100CFH.pdf

But I have my doubts given that the typical Rtheta J-A for =

an SOT-23 is
typically given as +500~+550=B0C/W.

I suppose that (roughly) 2" x 2" of 2oz copper is a fairly =

substantial
heatsink for the Zetex rating.

__

If anyone can do it Zetex can.
If Zetex can then Asian manufacturers are capable of copying =

them AND improving on what they do.
In the above datasheet Zetex claim 100 C/W for what they =

specifically refer to as a "High power dissipation SOT23 =

package". As most lunatics would not refer to SOT23 as high =

power dissipation this suggests that they are talking about =

THEIR specific implementation.

They also say 69 C/W for <=3D 5 seconds on FR4 etc so their =

100 C / W is clearly meant to be taken seriously.
They actually provide 4 figures of increasing machismo.

171 C/W on 15mm x 15mm x 1.6mm (PCB thickness) 1 ounce =

copper FR4 high coverage single side still air.

119 C/W 25 x 25 x 1.6 still air. 2 oz copper.

100 C/W 50mm x 50mm x 1.6mm ss 2oz still air.

69 C/W 5 seconds as above.


        R




-- =

http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist