• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

LM317 thermal resistance and heatsink selection

Thread starter #1
Looking for thermal resistance in the LM317 datasheet from TI, I found something which doesn't make any sense to me.

http://www.ti.com/lit/ds/symlink/lm317.pdf
Page 4

There're two TO220 packages, which seem differ in the thickness of the tab.
One of them is 4.2 ºC/W junction-case, which is close to the typical 5ºC/W assumed by many people. But the other one is just 0.1 ºC/W ??

:eek:

Can it be that LOW ?
I think that either I'm missing something, either there's a mistake in those figures.
Anyone knows?
Thanks
 

crutschow

Well-Known Member
Most Helpful Member
#2
Yes, that thermal-resistance value does seem to be abnormally low.
I suspect a typo.
For example this regulator (page 2) shows a thermal resistance of 3°C/W for that package.
I would use the value for the LM317 KCT package.
 

Latest threads

EE World Online Articles

Loading

 
Top