Fake lm338s

Thread Starter

Jarrod1024

Joined Apr 30, 2013
2
Hi, I recently ordered some lm338s from eBay, I had previously set up a lm317 circuit on my breadboard so I just replaced the lm317 with the lm338 but with a 22v input I can Only go down to 19v and the lm338 gets hot even with no load.
The lm317s worked perfect in this circuit, are these lm338s fake?
 

ErnieM

Joined Apr 24, 2011
8,377
Both devices have the same pinout, so if you wired it the same way it should work.

I searched for the part on EBay, got some curious Chinese hits where the parts have a logo that may be mistaken for the National Semiconductor stylized N but are really something else.

To be "fake" they have to say they are something they are not. I think this may be misleading packaging.

They are about twice the price at Digikey. USPS shipping is about $2.50 with 2-3 day delivery.
 

Thread Starter

Jarrod1024

Joined Apr 30, 2013
2
I think I'm going to order some from digikey then, is there any difference between the lm338t/nopd-nd and lm338t-nd? Also should an lm338 get warm at all with the output not connected to a load?
 

DerStrom8

Joined Feb 20, 2011
2,390
You say you bought these on ebay? Check the seller's rating. Read the customer reviews. If the seller has any less than 95% positive reviews, either read the comments left for the seller to see if you think it's worth the risk, or find a more trustworthy buyer.

Matt
 
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