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IC idiot

Aug 28, 2010
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Hello all.
I know very little about electronics so I am asking for help from you, the experts.
I am trying to either locate to buy or to find a cross reference for a 74168 IC.
Thats all I know of it....a 74168.
I did some research and see it's a Synchronous 4-bit up/down decade counter.
Thanks in advance for any help.
IC idiot
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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try a 74LS168

74 series is an obsolete TTL logic series. 74LS is more modern, has similar drive capability, speed, and input requirements, but consumes less power.

In most cases (although not all) you can pull a 74xx IC and replace it with 74LSxx

Finding one... That may be a problem.
 

Militoy

Aug 24, 2010
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Aug 24, 2010
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Area 51 ESG currrently has 83 pieces of a TI SN74S168N available with 1983 date codes(didn't check price)

Mouser has 94 pieces of an NTE74LS168A available (1994) FOR $3.10
 
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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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I swear I checked mouser. I must have typed 74LS186 or something :(
 

Militoy

Aug 24, 2010
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I swear I checked mouser. I must have typed 74LS186 or something :(

Mouser, Digikey, Newark, etc. have some real issues with the search parameters on their websites. The 'parametric search' feature - where you lay out component parameters one-by-one, and let the site search for you, is the biggest culprit. Often, the site will give you a null result - but searching by an alternate path, or a direct phone call will show parts in stock.

There are several ways to "backdoor" their stock lists - but sometimes you have to really work at it from several angles, keep an eye on supplies, and stay on your toes. As an example - I recently had an issue with sourcing an IC we're using in production. I learned during a chance social conversation while on vacation, that there might be some upcoming issues with supply of that part, because of a possible patent dispute involving the manufacturer. By the time I was back at work the following Monday - I discovered we had only a few week's supply of the part on hand - and an online search indicated that worldwide inventory was drying up. The search showed 300 pieces at Newark, and about 1300 in the UK at Farnell - plus some lower temp commercial parts in China. By the time I could get a purchase order through the system (about a half hour), the Newark parts were no longer available - though they still appeared up on their website. Now, things were getting serious! Since Farnell / Newark is one entity, we requested to purchase all of the UK stock. "Sorry - there's a limit of 300 pieces per buy, because of some kind of supply issue". 5 phone calls, and 5 separate purchase orders later, we secured all 1300 pieces - and won't have to redesign for at least 6 months.

Sometimes, you get stuck by obsoleted parts, and have to re-design a circuit, or find alternate sources for the parts, or variations (ROHS vs lead-bearing solder, different temp range, screened parts, different mfr, alternate packaging, etc). We've been forced to make 'lifetime buys' a number of times - but sometimes, there is another source, an alternate part, or 'hidden' stock. You just have to keep digging.
 

IC idiot

Aug 28, 2010
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Aug 28, 2010
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Thanks for all the help folks.
It seems 74168 isnt available anywhere.
Would 74LS168 be suitable in this design?:
74168 chip.jpg
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Impossible to tell from that very limited diagram.

Give it a try. 99% of the time LS-TTL can replace standard TTL.
 

shrtrnd

Jan 15, 2010
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Shouldn't be a problem.
LS is low power, schottkey (low noise).
(Just don't try the reverse, a circuit designed for 'LS' often won't work acceptably with the 74168).
Most people know it, but for IC idiot:
The the family IS TTL (Transistor-Transistor-Logic)
Prefixes usually identify the manufacturer, NTE is the company that bought out the old ECG (Sylvania line).
SN, denotes Texas Instruments origin
DM, old National Semiconductor
Suffix markings mean different things depending on mfgr. Can mean things like temperature range, package type (plastic or ceramic), and whatever else the mfgr might want to specify.
Just some helpful trivia for IC idiot.
 
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