Re: 74LS90, 74LS92 and other TTL are OBSOLETE???

Doing a search for some TTL Logics as 74LS90, 74LS92 and others common
use Logic ICs I have found that they are OBSOLETE??? !
Basicaly I'm looking for any package of them DIP, SO and also I don't
care much if it will LS, S, HC, HCT type!
So is it real that the standard TTL Logic ICs are going to obsolete?

NTE still carries replacements for the 74LS90 and 74LS92 as well as
many other otherwise-obsolete parts. Their parts are a decent
solution if you need to repair some older equipment, but are
generally too expensive to consider using in new projects.

These sorts of small logic and small-scale-integration chips are very
much an endangered species, and are widely listed by those
manufacturers who make them as "not intended for new design".

The trends these days seem to be:

- Low-voltage operation. 5-volt logic is passe.

- Very-small-footprint packages.

- Large, complex logical networks are generally implemented via
microcontrollers, PLDs of one sort or another, ASICs, and FPGAs.
Building complex logic out of simple DIP or large-surface-mount
logic ICs is only rarely done these days.

- A lot of single logic gate types are available in tiny little
packages (5- or 6-pin SOT-like) and are intended for adding small
amounts of logic "around the edges" of a more complex chipset.

What it boils down to, I think, is that if you need to repair some
older equipment or a project which used the old DIP/SO TTL parts, you
can probably do so but may need to substitute, scrounge, etc.

If you want to build something new, you'll probably be better off
designing it to use modern parts and techniques. You might find that
a simple PLD, or even a PIC microcontroller, could absorb the
functions for which dozens of TTL-logic parts were originally used.
You'll end up with a simpler, easier-to-build circuit.

--
Dave Platt <dplatt@xxxxxxxxxxxx> AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
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