We just ignore the data sheets and use the "Motorola" SOT23 pinout convention for all parts with that shared PCB decal.
3 1 2We do create a distinct pads "part" for every part, like vanilla SOT23 transistors or mosfets. But we reuse the common schematic symbols and PCB decals that are sub-elements of the "part".
Do you have a separate set of decals for every resistor value?
-- John Larkin Highland Technology, Inc lunatic fringe electronics
The problem, then, is the datasheet doesn't agree with the schematic.
As far as I know, we do. I don't think resistors are treated any differently than any other component. I'm sure they're copied from a "standard" one, though.
Don't think I've done this, but I've used wrong size/pitch before, or there's a one that I followed perfectly and still failed..:
A Harwin DB25 connector. THT, right angle. Three drawings: top view, side view, PCB drill pattern (top side).
The pin numbers were reversed (end to end) for the last drawing. Their drawings were inconsistent, not my following of them.
Sometimes you can't win.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
Sometimes identifying the "top side" isn't so easy, which can lead to more confusion.
Ahh, and I've been bothered by a great many "bottom view" footprints in my time. But it did indeed say top!
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
That's not really a problem. Emitter-base-collector are pretty obvious.
All our, for instance, 0805 resistors are the same library part, RES/0805. On the schematic, we edit the attributes of each resistor, namely "value" and "hti#", which is our stock number.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
On things like connectors, I usually ohm out an actual connector and compare that to the PCB layout. I mark pins with a sharpie pen, take a photo, and put that in the database PDATA folder for that part.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I meant the pin numbers on the datasheet then don't match the schematic and the board.
No, there is a separate library part for each part number. Underneath the covers there may be some sort of indirection, though. Don't know. I will admit that our system is a mess in many ways, though. There is no way to find anything in the database, for instance. If I want an N-FET, I have to go through all transistors, one by one, looking at its symbol. I then have to go to Dingily to see if I can find the part (usually not there). Repeat for a day or two. Connectors are much the same.
I know. For something as simple as a transistor, it doesn't matter.
With one pin number convention, I don't have to look up the data sheet when I'm probing, to find where pin 2 is.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
It can be hard to assure quality without buying physical parts. Sometimes impossible.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
You're sure it wasn't just the European vs American way of showing views? American drawings do it as though you were sliding the part along a concave surface without rotating it, whereas with European ones the surface is convex.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Well now you're gonna make me have to dig it out and copy the link...
(...)
Apologies to Harwin, it was Harting:
Specifies projection, and PCB view is both specified and an auxiliary drawing, so it doesn't matter. (Often, they don't even give you *that* courtesy.)
You look at it and it seems fine, but the longer you look, the more you're sure something's off...
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
looks like they copied the footprint from the male version, by hand.
-- \_(?)_
I once had it even worse with a real part. The pin numbers were printed (embossed) in the plastic part but had the numbering scheme from the opposite sex.
-- Reinhardt
The other annoying thing about right-angle connector footprints is that they usually don't say which direction the connector is facing.
Some D25 data sheets avoid the problem by giving no pin numbering hints at all.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
The convention is "looking at the pins" but there is no guarantee.
At least they're not wrong. :-(
This one's kind of specific at least, in that, if you assume the unspecified dash-dotted box around the footprint is the component area, then the wider side must be the connector end.
There's no way to tell which row of pins is in front, based on the ortho views. A better draftsman would provide an iso view or two. Which would also handily clear up any other confusion about orientation or pinout. Alas...
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
It's fairly safe to assume that the top row of contacts goes to the back row of pins.
that doodle of a truncated cone is supposed to indicate third angle.
-- \_(?)_
Yeah. I've never seen one that doesn't, but if I hadn't seen one before, I wouldn't know that.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: http://seventransistorlabs.com
We often flip opamps on the schematic; inverting vs NI circuits look better if the amp is flipped properly. Unfortunately, that also flips the power pins, so sometimes V- is up and V+ is down; that can be mindlessly connected wrong. Our checklist now makes us be sure we have power connected correctly.
Someone wanted to have two alternate opamp symbols, but that can get wrong too.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
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