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'[EE] How to determine pin 1 on this IC?'
2011\02\17@222457 by Nathan House

picon face
I'm trying to use a LM358 dual op amp IC and have a little problem; I
don't know which pin is pin 1. I can't seem to get my camera to take a
good picture of something this small, but it looks kind of like this:
http://farm2.static.flickr.com/1352/5179445393_b6b4d864e0.jpg. There's
no circle by the first pin, and there's no notch at the top.
Intuitively, it seems like with the text right-side-up (like in the
photo) the first pin would be on the lower left, but I don't know for
sure..

Any ideas

2011\02\17@223237 by PICdude

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face
Would be shocked to see if any of the pros say something different on  this, but I've personally never seen a chip that would have anything  other than the lower-left corner pin near the "X" as pin 1.

Cheers,
-Neil.



Quoting Nathan House <spam_OUTnathanpiclistTakeThisOuTspamgmail.com>:

> I'm trying to use a LM358 dual op amp IC and have a little problem; I
> don't know which pin is pin 1. I can't seem to get my camera to take a
> good picture of something this small, but it looks kind of like this:
> http://farm2.static.flickr.com/1352/5179445393_b6b4d864e0.jpg. There's
> no circle by the first pin, and there's no notch at the top.
> Intuitively, it seems like with the text right-side-up (like in the
> photo) the first pin would be on the lower left, but I don't know for
> sure..
>
> Any ideas?
>

2011\02\17@224653 by Nathan House

picon face
There actually isn't an 'x' on mine. I finally found a picture of the
one I have in an ebay listing:
http://cgi.ebay.com/10-x-LM358DT-LM358-Low-Power-Dual-Op-Amp-SOIC-8-SMD-IC-/320612943519?pt=LH_DefaultDomain_0&hash=item4aa605469f

See how there's no markings?


On Thu, Feb 17, 2011 at 10:32 PM, PICdude <.....picdude3KILLspamspam@spam@narwani.org> wrote:
{Quote hidden}

>> -

2011\02\17@225936 by Oli Glaser

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On 18/02/2011 03:46, Nathan House wrote:
> There actually isn't an 'x' on mine. I finally found a picture of the
> one I have in an ebay listing:
> http://cgi.ebay.com/10-x-LM358DT-LM358-Low-Power-Dual-Op-Amp-SOIC-8-SMD-IC-/320612943519?pt=LH_DefaultDomain_0&hash=item4aa605469f
>
> See how there's no markings?

Bit hard to tell from the picture, but It looks like it's probably a bevelled edge to indicate the side with pin 1 (bevelled edge to your left, pin 1 will be at top, should have details in one of the datasheets)

2011\02\17@230036 by doug metzler

picon face
I think the deal with those is that one edge is chamfered more than the
other, and in this case the chamfered edge is the one on the bottom as
you're looking at the text.

So Pin1 is the pin closest to the ST logo.

take a look at page 13:
http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00000464.pdf

DougM

On Thu, Feb 17, 2011 at 7:46 PM, Nathan House <.....nathanpiclistKILLspamspam.....gmail.com>wrote:

{Quote hidden}

2011\02\17@230709 by Oli Glaser

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face
On 18/02/2011 03:46, Nathan House wrote:
> There actually isn't an 'x' on mine. I finally found a picture of the
> one I have in an ebay listing:
> http://cgi.ebay.com/10-x-LM358DT-LM358-Low-Power-Dual-Op-Amp-SOIC-8-SMD-IC-/320612943519?pt=LH_DefaultDomain_0&hash=item4aa605469f
>
> See how there's no markings?
>

Just looked at the second picture - definitely a bevelled edge  (and the text orientation helps)
So it's bottom left in the pic.
Here's a good article on pin 1 problems:
http://www.evilmadscientist.com/article.php/pin1

2011\02\17@230711 by jim

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That indeed is the case in this instance

-----Original Message-----
From: @spam@piclist-bouncesKILLspamspammit.edu [KILLspampiclist-bouncesKILLspamspammit.edu] On Behalf Of
Nathan House
Sent: Thursday, February 17, 2011 9:25 PM
To: Microcontroller discussion list - Public.
Subject: [EE] How to determine pin 1 on this IC?

I'm trying to use a LM358 dual op amp IC and have a little problem; I
don't know which pin is pin 1. I can't seem to get my camera to take a
good picture of something this small, but it looks kind of like this:
http://farm2.static.flickr.com/1352/5179445393_b6b4d864e0.jpg. There's
no circle by the first pin, and there's no notch at the top.
Intuitively, it seems like with the text right-side-up (like in the
photo) the first pin would be on the lower left, but I don't know for
sure..

Any ideas

2011\02\17@230821 by Ray

picon
part 1 580 bytes content-type:text/plain; charset="us-ascii" (decoded quoted-printable)

picture looks like:
slope of epoxy package is more pointed on pin 1-4 side and more flat on pin 5-8 side
and/or
sometimes pin 1 has a different shape than other pins
Ray


On Thu, 17 Feb 2011 22:46:44 -0500, Nathan House wrote:
>?There actually isn't an 'x' on mine. I finally found a picture of
>?the one I have in an ebay listing: http://cgi.ebay.com/10-x-LM358DT-
>?LM358-Low-Power-Dual-Op-Amp-SOIC-8-SMD-IC-
>?/320612943519?pt=LH_DefaultDomain_0&hash=item4aa605469f
>
>?See how there's no markings?
>




part 2 181 bytes content-type:text/plain; name="ATT00001.txt"
(decoded base64)

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2011\02\17@231022 by Marcel Duchamp

picon face
On 2/17/2011 7:46 PM, Nathan House wrote:
> There actually isn't an 'x' on mine. I finally found a picture of the
> one I have in an ebay listing:
> http://cgi.ebay.com/10-x-LM358DT-LM358-Low-Power-Dual-Op-Amp-SOIC-8-SMD-IC-/320612943519?pt=LH_DefaultDomain_0&hash=item4aa605469f

>See how there's no markings?


On many IC's, orientation is denoted by the top being beveled along the side with pin 1.  In your photos, this appears to be the case.  The bottom edge of the chips you show appear to have a bevel on the bottom edge making pin 1 the pin on the bottom left

2011\02\18@005708 by Jesse Lackey

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face
I *hate* it when companies do this.  I've got rs485 SOICs from ST, and there is the same having to look real closely at them to figure out what is what.  ST: shame on u.  Seriously, put a recessed dot or anything else to make it clear, at the first glance, what is up.

Argh.

rant mode off.
J


doug metzler wrote:
{Quote hidden}

>>

2011\02\18@075718 by Nathan House

picon face
It looks like you guys are right, it does have a slightly beveled
edge. Kind of hard to see, though..

Thanks for your help

2011\02\18@081843 by Olin Lathrop

face picon face
Nathan House wrote:
> Intuitively, it seems like with the text right-side-up (like in the
> photo) the first pin would be on the lower left, but I don't know for
> sure..

That's my guess too in the absence of any other information.  Does the
datasheet show the orientation of the text with respect to pin 1 perhaps?


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2011\02\18@111832 by Herbert Graf

picon face
On Thu, 2011-02-17 at 22:24 -0500, Nathan House wrote:
> I'm trying to use a LM358 dual op amp IC and have a little problem; I
> don't know which pin is pin 1. I can't seem to get my camera to take a
> good picture of something this small, but it looks kind of like this:
> http://farm2.static.flickr.com/1352/5179445393_b6b4d864e0.jpg. There's
> no circle by the first pin, and there's no notch at the top.
> Intuitively, it seems like with the text right-side-up (like in the
> photo) the first pin would be on the lower left, but I don't know for
> sure..

I'd assume the same.

That said, I'd check the datasheet for that particular manu to be sure.

TTYL

2011\02\18@112759 by Mark Rages

face picon face
On Thu, Feb 17, 2011 at 11:57 PM, Jesse Lackey
<TakeThisOuTjsl-mlEraseMEspamspam_OUTcelestialaudio.com> wrote:
> I *hate* it when companies do this.  I've got rs485 SOICs from ST, and
> there is the same having to look real closely at them to figure out what
> is what.  ST: shame on u.  Seriously, put a recessed dot or anything
> else to make it clear, at the first glance, what is up.
>
> Argh.

Is it just ST who does this?  I wish they would knock it off.

I recently hand-assembled a bunch of boards with SOIC LM358 and it was
the ST part with a bevel.  About 10% of the boards failed because I
installed the IC backwards.  It's really hard to see the bevel unless
the light is just right.

Fortunately, there are plenty of manufacturers making LM358, so I will
make sure to use someone else's part next time.

Irrelevant for machine assembly I suppose.

Regards,
Mark
markrages@gmail
-- Mark Rages, Engineer
Midwest Telecine LLC
RemoveMEmarkragesspamTakeThisOuTmidwesttelecine.com

2011\02\18@123626 by alan.b.pearce

face picon face
> > I *hate* it when companies do this.  I've got rs485 SOICs from ST, and
> > there is the same having to look real closely at them to figure out what
> > is what.  ST: shame on u.  Seriously, put a recessed dot or anything
> > else to make it clear, at the first glance, what is up.
> >
> > Argh.
>
> Is it just ST who does this?  I wish they would knock it off.
>
> I recently hand-assembled a bunch of boards with SOIC LM358 and it was
> the ST part with a bevel.  About 10% of the boards failed because I
> installed the IC backwards.  It's really hard to see the bevel unless
> the light is just right.
>
> Fortunately, there are plenty of manufacturers making LM358, so I will
> make sure to use someone else's part next time.
>
> Irrelevant for machine assembly I suppose.

Exactly - the bevel along the length of the IC is probably designed so it will only go in the chip loader one way around, and I suspect that the moulding process is a continuous extrusion, so for the small percentage of chips that are hand assembled it isn't cost effective to include the dimple or notch on the chip body.
-- Scanned by iCritical.

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