1. Home
  2. Electronics Design
  3. ic pinouts

ic pinouts

Tube pin numbers were clockwise as seen from below, so I guess the people who first packaged ICs followed the CCW-from-above convention.

Big mistakes were physical symmetry and putting the ground pin in a corner [1]. TI introduced a logic series with Vccs and grounds on middle pins, but that didn't catch on.

I believe that every possible permutation of 1-2-3 pin numbers, CW and CCW, has been seen on various SOT-23 data sheets. And probably every possible SOT-143/343. People can't even decide on the physical location of the big pin, or what to number it. Some data sheets name the pins but don't number them. Some people offer part xxx and xxxR, with pins bent in opposite directions.

I'm doing a proto 4-layer board layout to test some oscillator circuits, and the SAV551 footprint just didn't look right. It isn't. I figure that there are 48 possibilities.

[1] with modern pick-and-place and inspection tools, rotated part errors hardly ever happen any more. 
--

John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
John Larkin
Loading thread data ...

Putting ground and power in the corners alone has probably cost billions of dollars in lost productivity/routing frustration/why-doesn't-this-shit-work-decoupling-issues over the past

50 years or so I figure, to prevent, what, destruction of the chip by installing it backwards? a pretty uncommon and immediately obvious error. A costly one too, maybe but only circa 1965.
Reply to
bitrex

I have seen a pcb where the inductor was placed 90degree wrong. The stepdown converter was working, but the efficency was only 10%. Very funny. :)

Olaf

Reply to
olaf

If you short the inductor, you get a linear regulator!

--

John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

I recommend examining an actual part first.

--
 Thanks, 
    - Win
Reply to
Winfield Hill

My layout guy just got the pin mumbers tangled. He called the big pin

1, and it's actually 2.

I have played with a real part, and the data sheet is correct. Weird but correct.

4s 3g

1d 2s

where 2 is the big pin.

--

John Larkin         Highland Technology, Inc 

lunatic fringe electronics
Reply to
John Larkin

Am 21.05.19 um 04:18 schrieb John Larkin:

Some Avago Schottky diode rings etc had a weird way of counting. (No longer important, extinct)

I have made a test layout Thursday evening and got the boards from PCBway in China on Monday morning. The world is shrinking, it seems. :-)

First thing I noted was that my decal for the LT3094 is too small. Mea culpa. :(

I have made up for it with very artsy soldering. All in all $4 for PCBway and $26 for the transport by DHL, 10 boards. There have been worse times.

Cheers, Gerhard

Reply to
Gerhard Hoffmann

And when the wrong reel of parts is put on the machine, ALL of the boards are wrong in the same way.

Haven't had that problem in a very long time now.

Reply to
boB

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.