LM337 & LM337T - Page 1
Forum section: electronics / general

author: G7PSK
author_rank: Super Contributor
timestamp: March 04, 2012, 05:42:18 pm
content: I was going through some old stuff and found that I have a quantity of Motorola LM337 and LM337T. I think they were part of a job lot I purchased at an auction in the late 1980's along with a whole lot of other things that either came out of the Pye Cambridge factory or the University labs. I was wondering what the difference is between the plain LM337's and the LM337T's as I cannot find anything on the data sheets look for LM337T and I just get LM337.

author: SeanB
author_rank: Super Contributor
timestamp: March 04, 2012, 05:53:18 pm
content: I think they are the same, the T came in a TO3 housing, whilst the unmarked ones were mostly in TO220. Some had a higher rating in the TO3 casing, and at least they can dissipate more power as they have a lower junction case thermal resistance.

author: IanB
author_rank: Super Contributor
timestamp: March 04, 2012, 05:56:33 pm
content: But the Fairchild datasheet gives ordering information of LM337T for the TO-220 package. Looks like the T is basically of no consequence.

author: Tube_Dude
author_rank: Regular Contributor
timestamp: March 04, 2012, 06:10:10 pm
content: LM337T are TO-220 package...See page 2 of PDF:http://www.ti.com/lit/ds/symlink/lm117.pdf

author: G7PSK
author_rank: Super Contributor
timestamp: March 04, 2012, 06:13:53 pm
content: They are all TO 220, Will they be any good after all this time I don't want to have to test them all as it is not like a transistor the only way I can see to test them is build a circuit and put them in one at a time is this likely to be worth it or are they just bin fodder now.

author: Tube_Dude
author_rank: Regular Contributor
timestamp: March 04, 2012, 06:17:23 pm
content: Sorry, by mistake, I give the PDF of the LM 117, but for LM337 you have the same. Still at page 2 :http://pdf1.alldatasheet.com/datasheet-pdf/view/257431/LINER/LM337T.html

author: IanB
author_rank: Super Contributor
timestamp: March 04, 2012, 06:19:52 pm
content: Quote from: G7PSK on March 04, 2012, 06:13:53 pmThe only way they can fail is to have been electrically damaged by someone before you got them, or possibly by oxidation of the internal chip if oxygen managed to diffuse in from the outside over the years and corrode things.Another possibility is that fabrication and design techniques have improved and modern ones perform better than old ones.But I'd guess they will work fine. My thoughts above on what can go wrong are very low probability. IC's generally don't fail if stored and treated kindly.

author: Tube_Dude
author_rank: Regular Contributor
timestamp: March 04, 2012, 06:27:39 pm
content: Quote from: IanB on March 04, 2012, 06:19:52 pmI agree with Ian.Being a variable voltage regulator is very handy to use and have around. Once I use a (117) to regulate the supply of the screens output tubes, in a tube amplifier, at an amazing 300 V DC...

author: T4P
author_rank: Super Contributor
timestamp: March 04, 2012, 06:41:02 pm
content: LM337K = normal packaging LM337/T = TO-220

author: G7PSK
author_rank: Super Contributor
timestamp: March 04, 2012, 06:48:59 pm
content: Thanks for all the info. I am now wondering why Motorola labeled some with the T and left it of others after all they are all TO 220 Obviously different batches.

author: T4P
author_rank: Super Contributor
timestamp: March 04, 2012, 06:59:44 pm
content: Quote from: G7PSK on March 04, 2012, 06:48:59 pmI believe i have both NatSemi LM337T and LM317T (New logo) TO-220's and STMicro's LM337 in TO-3Phew , took a long time to search for the logo .http://www.advanced-tech.com/ic_logos/ic_logos.htm