Does a SOT-23 (1,2,3) = BCE PNP exist? - Page 1
Forum section: electronics / projects

author: 741
author_rank: Frequent Contributor
timestamp: December 23, 2022, 10:21:10 pm
content: See picture

author: Benta
author_rank: Super Contributor
timestamp: December 23, 2022, 11:41:17 pm
content: Must be some very British humourous thing for insiders posted at the pub.What's your point?

author: Someone
author_rank: Super Contributor
timestamp: December 23, 2022, 11:58:59 pm
content: Quote from: Benta on December 23, 2022, 11:41:17 pmProbably built some boards with the "wrong" pinout. There are/were specialty suppliers who deal with this, but dont have their names on hand (and unlikely to be cheap enough to match this forums demographics).

author: ledtester
author_rank: Super Contributor
timestamp: December 24, 2022, 12:24:59 am
content: You're not the only person who has looked for such a part:-http://dangerousprototypes.com/forum/index.php?topic=3914.0-https://forum.robodoupe.cz/viewtopic.php?t=954(in Czech)There is a EE Stackexchange question which discusses the same problem for an NPN. One idea is to flip and rotate the part 120 degrees:https://electronics.stackexchange.com/a/493607/but also see the other proposed solution.

author: 741
author_rank: Frequent Contributor
timestamp: December 24, 2022, 01:19:26 pm
content: HiNo, it was not anything humorous - not intentionally that is.I have a footprint with the 'wrong' 1,2,3 pin sequence. I am pretty sure this stems from at least one data-sheet which showed pins 1,2,3 like this1---23Thus, initially I designed SOT-23 footprints to that convention. I later realised that SOT-23 obviously includes SOT-23(6) which must follow the normal anti-clockwise pin convention.Anyway I'm resigned to a re-design, although I'd like to get one PCB made up as-is so as to test the circuit.

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: December 24, 2022, 07:09:30 pm
content: When a related question was asked previously, Mike of Mike's Electric Stuff suggested the following:> It's not hard to bend the leads to mount SOT23's upside down - just need a couple of spiky implements - one to hold the body down, the other to push the leads down flat - reflows no problemPerhaps that will get you over the line on your prototype at least?

author: Kleinstein
author_rank: Super Contributor
timestamp: December 24, 2022, 07:27:17 pm
content: There are some SMD parts that come with alternative pin_outs. However with transistors there is usually just the option to rotate - so no real need for a different pinout.Usually pin 3 (the single pin on one side) is the substrate and thus the collector of BJTs and the gate of JFETs.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 24, 2022, 08:33:11 pm
content: For just one prototype just mount the part appropriately as suggested above. No big deal.And yes testing the board before redesigning it is a good idea. It may not be the only problem you'll have to solve.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: December 26, 2022, 03:40:48 pm
content: You should always be careful with SOT23.A problem with this package is that there is no universal consensus of what the location of pin 1 is. (Although alternative pin numbering seems to be become less common).

author: bostonman
author_rank: Super Contributor
timestamp: December 27, 2022, 12:10:08 am
content: Why not cut the traces and run jumper leads?Or as suggested, mount upside down; you can use solid bus wire and don't need to stress the leads by bending them.