Identifying pin1 on SOIC component

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MORA99
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#1
Posted by MORA99: Wed. Jun 8, 2011 - 04:07 PM
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So I got this cute little 74HC125N from phillips, with 14legs and all.

Nice text printed on top of it, proclaming its name and proud parents.

...but where the heck is the pin1 mark?
No circle on top, no dent in either end.
Production seems to be poor enough, that a small mark is unnoticeable to the molten plastic.

Data sheet : http://focus.ti.com/lit/ds/symli... (Page 13 shows the package).
Is there something obvious I am missing.
Let me know of a picture of the real thing can help, its pretty tiny though.

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Learning and Information, General Electronics
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chartman
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Posted by chartman: Wed. Jun 8, 2011 - 04:20 PM
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Some SOICs have a chamfer all along the side that is starting at pin1 and no DOT/dimple.
See page 13 of the pdf you pointed to !!! :)

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mhatter
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Posted by mhatter: Wed. Jun 8, 2011 - 05:18 PM
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If and only if there are no other markings reading the text left to right, pin 1 will be on the bottom left. For an SOIC-N package it should be:

N
SomePartText
MorePartText
1

I have too many hobbies.
s-conductor.com

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MORA99
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Posted by MORA99: Wed. Jun 8, 2011 - 05:32 PM
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Right, one side is angled a bit, and when oriented correctly, that means pin1 can only be one place.

The text is also as mhatter showed.
Seems a bit silly, needs a magnifyer to spot the edge, when theres plenty of room for a marking.

Thanks! :)

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