Hi to everybody! I'm new to this list.
I'm trying to learn to use Layout from Cadence and I've to place a
component in a SOT23 package. I've searched it in the standard
libraries but I was not able to find it. Does anybody know where I
can find this footprint or how I can draw it by myself (any
tutorial...?).
Thanks a lot!
Andrea
Andrea, the library would be the SM.LLB Library, atleast for v9.1 it was so it might be the same.
A word of caution though ! Make sure the pin numbering scheme for the schematic symbol matches the correct pad placement numbering for the footprint in layout. Also alot of the sm parts in layout were not very well made i.e pad size were incorrect for manufacture of a real pcb. Soldermask on most of them was not oversized enough for the pad land.
At one time Orcad created a ipc standard library of SM footprints for layout so the SOT23 part might be in such a library also. You can check the download section of the Orcad/Cadence website.
Your safest bet on the footprint if in doubt is to look at the part manufacturers data sheet for a land pattern and create one or modify the existing one.
Good Luck...
Paul H
It still can be found in the SM.LLB library in 20 flavors. Another way of finding parts is use GREP (or you can use M$ file search utility) to search for text strings in the library files. In your case, grep -i sot23 *.llb The reason I use GREP is I can use a batch file to find all the footprints for a project.
As Paul states, don't trust Orcad's footprints. You should check them against trusted footprints and then store them in your own library. About 100% of Orcad's footprints are unusable out of the box. Better yet, learn to make this from scratch. Making your own footprints is a necessary skill to learn for any PCB program.
-- Mark
Hello Paul,
Oh yeah! There really is no standard and even within the same manufacturer I have seen two different numbering schemes. And I have seen lots of people getting a black eye because of it. One of them is yours truly :-(
Regards, Joerg
Count me in. Lately I made it a rule to always double check all three pin devices especially when it comes to function vs pin number and the corresponding footprint match. Been there and burned. Here is what prompted me.
SOT-223 package 5 volt regulator
We later decided that a LDO from National would be a better choice. Of course the board was already built.
Like two gloves
Regards,
Boris Mohar
Got Knock? - see: Viatrack Printed Circuit Designs (among other things)
void _-void-_ in the obvious place
I have multiple copies of the same 3-pin footprint under different names. The footprint name I use is the same as the device name. This way, if I have not used the device before, the footprint is not found, and I can then make sure the schematic and footprint pins are matched when I make yet another copy of the specific footprint. So far I have not been bitten a second time by this particular problem.
Regards Anton Erasmus
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