74 logic families?

Other Hardware General Electronics
1

Hi,

I've been using components from the 74LS family recently. But my current application might actually need the best performance available. Which one of the 74 logic families is the fastest? I'm not really concerned about the power consumption at this point...

Thanks,
Kari

2

Search for PO74G00A, those are into GHz range.
The 74AVC8T245 series go up to hundreds of MHz.

What is your project ?

3

kbrown:
Hi,

I've been using components from the 74LS family recently. But my current application might actually need the best performance available. Which one of the 74 logic families is the fastest? I'm not really concerned about the power consumption at this point...

Thanks,
Kari

You never use anything but CMOS these days so drop all the S, LS, ALS, F etc and
move over to HC, HCT, AC, LVC, ...

For static power consumption you immediately benefit greatly of course, HC are the
general workhorse from 2V to 6V, LVC are 3.3V and faster but tolerate 5V inputs.
Once you're into the faster families you have to start worrying about board layout and
signal impedances more. 3.3V is probably your supply of choice for faster designs
anyway since a lot of fast chips are 3.3V tolerant but less likely to be 5V tolerant.

Surface mount is the rule not the exception with high speed logic these days, note.

4

Thanks for the input guys! I'll keep this in my mind should I need to get more performance out of what I'm doing.

I've basically got a circuit that measures the phase shift of two analog (sinusoidal) signals. It's implemented using voltage comparators triggering binary counters. I'm basically looking for when the two signals are in phase. The higher the frequency, the higher the performance requirement is... Hence the question...

5

For ripple counters upto 220MHz seems doable with the fast CMOS families (there's
also VHC I note), but above that current-mode logic (ECL) is required, and that's rather
more specialised.

6

200+ MHz sounds plenty for what I'm doing. Thanks Mark!

7

Caltoa:
Search for PO74G00A, those are into GHz range.

Wow, these are some small scale integration circuits. If you can design with such small building blocks, why not use a more established and frankly faster family like MECL?

Fairchild says these counters are good to 210Mhz (5V) and they will sample 10 of them at a time to you for free if you register with them. I know this for a fact, I have 20.

http://www.fairchildsemi.com/pf/74/74VHC4040.html?keyword=74VHC4040