SOT23 pin numbering

[Joerg]

Hello Brad,

Usually by the time the parts have been properly checked, you
could have made them from scratch just as quickly. If you don't
believe me just consider what you must do to thoroughly check
them? What do you need to do when creating them from scratch? Not
much difference is there? The actual creation/drawing/placing
time is far less than the detailed measures and calculating the
land pattern geometry.

In Eagle a creation from scratch takes a lot of time, more than it did
for me in OrCad. But there are easy ways to check things out: Place all
the components you want to use or where you suspect irregularities on a
schematic. Connect them in a way that allows easy identification where
drain, source etc. should be. Switch to "PCB", scatter them on there,
hit "autoroute" and print it all out. Magnify, so you have an easier
time to measure against mfg pattern specs.

That all takes just a few minutes but then you know whether the
dimensions are right, pinout is correct etc. Of course, this is only
time efficient if you use an integrated schematic/layout software.

Regards, Joerg

 

[Joerg]

Hello James,

Ah! I didn't realise you were using different schematic and layout tools.
I've never been in that position myself but I see where your coming from
now.

We usually don't do layouts. If the layouters were to use Eagle as well
things would be easier. But in the US most of them don't.

Regards, Joerg

 

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Hello Brad,


In Eagle a creation from scratch takes a lot of time, more than it did
for me in OrCad. But there are easy ways to check things out: Place all
the components you want to use or where you suspect irregularities on a
schematic. Connect them in a way that allows easy identification where
drain, source etc. should be. Switch to "PCB", scatter them on there,
hit "autoroute" and print it all out. Magnify, so you have an easier
time to measure against mfg pattern specs.

That all takes just a few minutes but then you know whether the
dimensions are right, pinout is correct etc. Of course, this is only
time efficient if you use an integrated schematic/layout software.

Regards, Joerg

To answer your original question, there is no standard. I have done
what others have suggested and created multiple footprints called
SOT23, SOT23B, SOT23C

It is a huge error-prone mess. Every SOT23 in a layout one needs to
verified with a data sheet.