Regarding Logic Family selection of IC's

Thread Starter


Joined Jan 28, 2009
Hi all,
I am working on a industrial project[ welding controller ] based on AT 89C55WD, i need clarification on follwing points.......

:confused:1] While selecting IC's for industrial projects which family[TTL,CMOS,LS,ALS,HC,HCT ....etc.] should we consider. I am working with 20MHz crystal oscillator. I need low power consumption IC's.

For testing purpose i used IC'S from local market, with which my project is almost on the way of complition. I am using AT89c55wd,74165,74164,74244,AT24c04.

Plz help on this logic family selection as i want to order new ics from FARNELL distributor.

:confused:I think with all the logic families pin diagram remains same.

:confused:Whether PCB designing changes with Logic Family of IC?



Joined Apr 20, 2004
I use distrubutors in another part of the world, so I can't speak about Farnell.

I seems as if you have made you selection, as you specific mention type numbers that are for the original TTL family. They are not low power, though. Something like 74HCTxx would do better for that.

What you will face is an increased possibility of interference due to higher input impedances. You can obtain data sheets to see the differences between 7400 and 74HCTxx chips.

Your description of "industrial projects" doesn't give any specifics about operating conditions.