Opamp orientation?

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#23
xrk971 said:
I think you did it correctly. Pin 1 is referenced to bottom left of chip if you can read text. A quick google image searches turned this up. Looks same as your orientation.

s-l300.jpg


PICT0841.jpg


Very nice opamp BTW.

http://www.analog.com/media/en/technical-documentation/data-sheets/AD797.pdf
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Hi, X

The item in question is not the same as you showed. There is no dot marking pin 1. I took the approach you mentioned (using the text/marking). I do not have any knowledge/experience of this item, thus the question.
 
#28
By looking closely once again at the picture in the opening post it looks like the chip is oriented correctly since it has its beveled edge facing bottom and there is a more or less clearly visible trace from pin 1 of the adapter to what should be pin 1 of the chip (according to the beveled edge position). The problem I see with the chip is the missing dent/dot indicating pin 1 which probably means that the old part number has been mechanically polished off and the new marking (fake) has been printed. As already suggested earlier in this thread it's safer to throw it away then to try to make use of it without confidence, especially when it comes to such a part as AD797, IMO.
 
#29
There are a few different ways it is done, but in each case it is obvious which one is pin 1. Dot, cut corner, beveled edge, small indent at the pin position, etc. So even if you don't know what a particular manufacturer uses, it is always pretty obvious which one is pin 1 or which is the side with pin 1 on it, which gives the same result. Stop worrying ;-)

Jan
 
#31
Lo_Tse said:
Hi, X

The item in question is not the same as you showed. There is no dot marking pin 1. I took the approach you mentioned (using the text/marking). I do not have any knowledge/experience of this item, thus the question.
Click to expand...

I am not referencing dot - picture happens to have it. Just go by text if readable (not upside down) then pin 1 is bottom left.
 
#33
jan.didden said:
There are a few different ways it is done, but in each case it is obvious which one is pin 1. Dot, cut corner, beveled edge, small indent at the pin position, etc. So even if you don't know what a particular manufacturer uses, it is always pretty obvious which one is pin 1 or which is the side with pin 1 on it, which gives the same result. Stop worrying ;-)

Jan
Click to expand...

Jan,

Without knowing much (all I know was the dot before this occasion arose), I assumed that when the text/marking is oriented properly (not upside down), the pin on the lower left hand corner would be pin 1. I made that assumption because many manufacturers kind of adopt this convention. I went back and check. Indeed, the "lower" edge (when the text/marking is oriented properly) is slightly beveled. So I think I guessed correctly.

Now I learn a little more about opamps 😛

Regards,
 
#34
from what I found out so far, there seems to be no universal convention
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The convention is the beveled edge as the reference for the pin 1 side.
They all follow it.
The dot, the "U" shape at the end are optional and change based on the packaging house molds.
I am looking at the drawing for a LM4562D, it shows the index area, but does not specify exactly what is placed in the index area.
If you look at the package drawing, they usually reference a JEDEC package that is the industry standard.
In this case for a 8 pin soic with 50mil pin spacing, it MS-012 variation AA.
Sometimes the data sheets editors forget this reference, but it is basically implied and a well known fact.
 
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