74HC86 has schmitt triger inputs or not?

Log in or register to post comments
Go To Last Post
6 posts / 0 new
Author
Message
incal
incal's picture
Level: Hangaround
Joined: Fri. Aug 1, 2003
Posts: 396 View posts
#1
Posted by incal: Sat. Feb 1, 2014 - 08:39 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I can find nand and inveter logic with schmitt triger inputs.

But when it comes to xor gate, it seems unclear.
I looked at the datasheet from nxp year 2007. it says it has a schmitt triger action (but it does not say it has a schmitt triger input it says only action?!?)

Interestingly the same datasheet from NXP but version of the year 2012 does not have anything for schmitt triger inputs or *action*.

Does 74HC86 have schmitt triger inputs as before?!?!? (very silly question but according to datasheets I am confused)

________________________________ We dream of a world where current does not need the voltage to flow.

Tags:

Learning and Information, General Electronics
Top
js
js's picture
Level: Moderator
Joined: Wed. Mar 28, 2001
Posts: 28665 View posts
Location: Sydney, Australia (Gum trees, Koalas and Kangaroos, No Edelweiss)
Posted by js: Sat. Feb 1, 2014 - 09:37 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I'm using that chip on a prototype at the moment, the original 74C86 was not designed as a schmitt trigger input, in fact I have seen that chip being preceded by 74C14 schmitt trigger.

The one from NXP seems to have "schmitt trigger action", I guess most modern CMOS devices do, but it may not be the case with the same chip from another manufacturer. It may be best to ask NXP support directly for a clear statement and if that's the case make sure that ONLY NXP devices end up being used in your boards.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

Top
incal
incal's picture
Level: Hangaround
Joined: Fri. Aug 1, 2003
Posts: 396 View posts
Posted by incal: Sat. Feb 1, 2014 - 10:06 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I searched at farnell all posibilities from various manufactorers.
Be carefull NXP datasheet is updated and in the new datasheet there is no sign for schmitt trigger.
Only the company Diodes has schmit triger inputs but it is not hex, only single gate sot26.
It can be that the technology has advanced and they developed a better way for the hysterisis.
TI and NXP has over 20 variants of 78XX86 but none of them mentions anything abaout schmitt trigger or hyteresis.
I am confused. In emergency case I can use 2 seperate single gate ICs from the company DIODES.

74HC14 is only schmitt inverter so useless for me. I would need the schmitt triger input xor gate.

________________________________ We dream of a world where current does not need the voltage to flow.

Top
gchapman
gchapman's picture
Level: Raving Lunatic
Joined: Tue. Jan 9, 2007
Posts: 9534 View posts
Location: Arlington, Texas, u.S.A.
Posted by gchapman: Sun. Feb 2, 2014 - 01:05 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

incal99 wrote:
Only the company Diodes has schmit triger inputs but it is not hex, only single gate sot26.
Diodes Inc has some quad 86s:
[url]http://diodes.com/catalog/standa...

"Dare to be naïve." - Buckminster Fuller

Top
Who-me
Who-me's picture
Level: Raving Lunatic
Joined: Sun. Mar 25, 2007
Posts: 2032 View posts
Posted by Who-me: Sun. Feb 2, 2014 - 05:08 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Logic Companies are known to be slack in this area.
Diodes makes some noise about Schmitt, but not all their variants spec it either !!

If you want a part code where (pretty much?) all vendors DO mention Schmitt, look at the 1G57/1G58/1G97/1G98 series.
(and some also have 1T57/1T58/1T97/1T98,which target Logic level translation).

Even there, finding vendors who show Icc/Vin sweeps, is very hard.

and to underline that, NXP family documents on VHC/T series say this
Schmitt trigger action at inputs

http://www.nxp.com/documents/bro...

but the Data sheets for
http://www.nxp.com/documents/dat...

'forgets' to spec Schmitt behaviour !!

Top
incal
incal's picture
Level: Hangaround
Joined: Fri. Aug 1, 2003
Posts: 396 View posts
Posted by incal: Sun. Feb 2, 2014 - 08:23 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hex xor fromm all other than diode do not mention schmitt.

I have acces to farnell and RS . They have only xor from the company diodes with single gate.

I am surprised that MCUs can be found much easily and in all variants than logic nowadays.

I suspect that all new CMOS has this extra schmitt triger transistors and resistors at the input or they found another cheap way ,they can not call it schmitt triger but compatible. Is the word schmitt patented or needs licence?

________________________________ We dream of a world where current does not need the voltage to flow.

Top