Obscure ICs

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jaem
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Obscure ICs

Post by jaem » Wed Oct 31, 2007 11:34 pm

Hi all,

I got some of the TTL ICs from Phil's Up For Grabs post a while back, and there was one chip, the TI #SN87723N, that I am completely unable to find any info on. Google actually turned up 0 results. Is there anywhere I can lookup obscure/custom/military parts, or at least find out if something falls into those categories? I have no clue where these came from (I PM'ed Phil to enlighten me), but TI's website has no record of them either. I'll have to call them tomorrow.

btw, TI's tech support # has a 972 area code. Is that a toll number? I looked it up on wikipedia, and it is somewhere in Europe, but I didn't see anything about Canada.

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CeaSaR
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Post by CeaSaR » Thu Nov 01, 2007 1:55 pm

jaem,

I googled area codes and came up with this:
http://www.bennetyee.org/ucsd-pages/area.html

972 is in Texas - listed as Dallas / metro. I believe that would be a toll call :shock:

Good luck on your quest for enlightenment at TI!

CeaSaR
Hey, what do I know?

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Post by haklesup » Thu Nov 01, 2007 4:23 pm

More clues, Any other markings, what is the package and pin count?

I looked in my old IC master 1983 and 1992 and couldn't find that number but a bunch of others starting with 87xx had to to with early 8 bit processors. If you have a 28 or 40 pin DIP, it may be processor or memory related.

Smaller 14 to 20 pin narrow DIP typically have power pins on the corner. Could take a guess and power it up. Probably figure out inputs from outputs but that's about it.

You can take a shot in the dark with TI tech support but they probably won't know anything about devices not in production unless you are lucky and get the old timer (if they have one).

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Post by jaem » Thu Nov 01, 2007 7:06 pm

Thanks for the info...
it's a 14-SPDIP - it looks pretty much like all the other TI chips that came with it, aside from the fact the the part number is off to the side, for no apparent reason. On the other end, there's the TI logo, and above it, the number 7740

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Post by jaem » Thu Nov 01, 2007 7:07 pm

wait a second... on the bottom, it says 74S32, and my other TI chips all have some permutation of their model numbers on the bottom too.
Darn! and I thought it was something interesting... I guess I'll power it up and check, anyways, though - I'll get back to you guys about it.

Thanks,

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Post by jaem » Thu Nov 01, 2007 7:09 pm

CeaSaR wrote:jaem,

I googled area codes and came up with this:
http://www.bennetyee.org/ucsd-pages/area.html

972 is in Texas - listed as Dallas / metro. I believe that would be a toll call :shock:
CeaSaR
I know it would be long distance - I was wondering if 972 numbers were included in the evil "900 number" extra charge thing. But I guess if it's a normal area code, it wouldn't be...

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Post by Robert Reed » Thu Nov 01, 2007 10:20 pm

Jaem
I beleive your 74S32 might be short for SN 74S32 which is a shockley TTL Dual input Quad OR gate. Check it Out here:
Google---SN74S32 and compare pinouts

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Post by jaem » Fri Nov 02, 2007 12:18 am

Thanks Robert, although I had that memorized from last year's electronics courses ;) I didn't think to check the bottom, and seeing as all my TI chips have numbers on their bottoms that are related to the ones on the tops, that's what I figure it must be. I will have to make sure, though, and I'm still wondering why they would have a completely non-existent number on the top. I can't think of any reason for internal/custom numbering for such a generic chip. Phil[ba] said they were floor-sweepings from an Intel assy. line c. 1985...

EDIT: I don't know if TI has gotten back to me, because my school's mailserver was down today.

I'll probably just break out a breadboard and 7805 during lecture tomorrow, and check it out. Just hope the Magic Smoke doesn't come out if it's not what we think... ;)

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Post by Robert Reed » Fri Nov 02, 2007 9:57 am

Jaem
The original top number doesn't seem to correlate with any in house numbering system I have ever seen. Also, I have never seen such an array of packaging for the same chip which is quite confusing. They run any where from 14 DIP to 28 pin SMD, with every imaginable configuration in between these. I am wondering since Intel might order such large quantitys of these chips that maybe TI might have set up a special variation of their line just to accomodate board insertion or special tape reeling for Intels requirements. The good thing is that you have the common 14DIP version and almost certainly will be Vcc on pin 14 and Vee on pin 7, so you are probably safe to plug it in in that fashion. Then I would use a signal injector with a 1000 ohm source impedance and scope for further investigation as to prove out pin assignments. Also, OR gates are a "dime a dozen", so blue smoke will not be disasterous if that should occur as they are cheaply replaceable. Good Lucck..

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Post by haklesup » Fri Nov 02, 2007 10:11 am

It's definately a mistry why they would put the part number on the bottom. Unless someone ordered them that way, you did say the logo was on top. If 7740 is the date code, it dosen't make sense to say intel wanted them that way in 1985.

Internal P/N is possible but lot code is more likely. Means nothing to us but it allows them to trace manufacturing problems back to the wafer if necessary.

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Post by jaem » Fri Nov 02, 2007 3:24 pm

well... I phoned TI, and they couldn't officially say anything about it. All you could tell me was that "74S32 is a real part number", but he wouldn't confirm or deny whether this chip was in fact a quad OR, or what the number on top might mean. He basically gave me the runaround.
I'll probably get time to go to the lab and test it tonight. Unfortunately, I don't think that the lab I have access to has a logic analyzer - that would make things easier.

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Post by jaem » Fri Nov 02, 2007 3:26 pm

haklesup wrote:Internal P/N is possible but lot code is more likely. Means nothing to us but it allows them to trace manufacturing problems back to the wafer if necessary.
I guess that could be, but it's interesting that the number is SNxxxxxN - the pre-/suffixes fit with a TI logic chip, but the actual number doesn't.

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Post by Robert Reed » Fri Nov 02, 2007 5:22 pm

No logic analyser needed here as a simple DMM will cover all tests.Once chip is in place and powered up,and using data sheet pinouts, simply place voltmeter from suspected out put to ground and by using current limliting resistors (1K or so) and clipleads, inject TTL level highs and/or lows at respective inputs. If truth table looks normal then you have a quad OR gate as suspected. If things don't work out, then you blow the IC. So whats the loss - only a defective chip that you originally were unsure of what its function was to begin with. If OR gates are what you really need, 1$ and some change will buy you a new handful and better yet they will be the newer C-Mos 74Hcxx series which will probably outperform your chip in hand also of which most will be compatable with TTL levels. Unless this is a lab challenge type of experiment-don't waste your time.

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Post by Robert Reed » Fri Nov 02, 2007 5:24 pm

Scratch

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Post by jaem » Fri Nov 02, 2007 5:25 pm

turns out it is apparently just a 74S32, however, TI also replied to my e-mail and said it wasn't in their records anywhere... which still makes me wonder why they would give it a different number.
oh well...

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