74154 TTL IC in Surface Mount (SOIC)

[xanatos]

When I started designing digital stuff, I used to use the 7400 series extensively. Now that they have nearly all become available in SOIC (Surface mount) packages, I have been continuing to design with them... BUT - one of the chips I use a LOT is the 74154 - 4 line to 16 line mux/demux - and everybody lists it as OBSOLETE! It was a VERY versatile chip for selecting/scanning etc. So - does anyone know what chip "replaces" it - function-wise? 4-bit binary input, 1 of 16 output lines selected. Anybody???? I would hate to have to make an otherwise full SOIC board with the one huge fat 24 pin DIP in the middle of the whole thing....

Thanks for any leads you may have.

Dave

 

[phenol]

74HCT154 ...

 

[xanatos]

The HCT did the trick - I found SOIC versions on DigiKey. Thanks!

I guess C, LS and F are all history!

Dave

 

[phenol]

HCT is a direct drop-in replacement of LS series. It is a CMOS family that has certain advantages over its bipolar older cousins. HC may also work, but u must make sure that there are no floating inputs in ur design-there is no provision of a circuit keeping the unused inputs in 1-state. Due to its vy high input impedace/CMOS/ any noise coupled onto a floating input may result in erratic behaviour.
there's another family - AC /advanced cmos/ -much faster, shorter propagation delays etc...not sure if '154 exists in this variant, though

 

[xanatos]

...certain advantages over its bipolar older cousins.

Like not needing regular doses of Lithium?

Thanks for the info, I had heard of the HCT family before, but never really knew what the differences were. I'll watch for the AC stuff too.

I used to do a lot of high-speed switching (80+mHz) and used the F series a lot... showing my age I guess. Now most of my hobby stuff is reaction/response/sensing/control, so speed and rise times in the nanosecond range aren't an issue any more!

Have a great holiday, whatever it is for you!

Dave

 

[phenol]

[quote author=phenol link=1198445576/0#3 date=1198479215]...certain advantages over its bipolar older cousins.

Like not needing regular doses of Lithium?


Have a great holiday, whatever it is for you!

Dave

[/quote]

If you run your circuits off Li-ion batts- no doubt HC MOS will drain less current at low switching speeds compared to Std TTL and even LSTTL ... so, less Li consumption by them and by you as a consequence

Christmas for me is probably similar, if not the same, to what it is for you. Im East-orthodox, however, during the last 2 decades we have adopted most of the western customs, Halloween makes no exception.

So, thanks Dave and enjoy the holidays!

-Hristo