Re: 74??00

Kurt Mahan wrote:

> Does anybody have a table of the various designators and the specs for each?
>
> So:
> none

The original.

> S

Schottky. Faster, power hungry.

> LS

Low-power Schottky. About the same power draw as the original, but faster than
the original (but slower than 'S').

> HC

High-speed CMOS. Speed about same as original, power VERY low.

> HCT

High-speed CMOS, but with TTL logic level input voltages.

> LV

Philips Low Voltage family, capable of operation on anything from 1 to 5.5 volts.

> LVT

Pretty much the same thing, but really made for 3.3 volt operation while working
with TTL input voltage levels.

> etc...

74C series, wide voltage operation, slow as hell.

74H series, fast power hog, about same speed as 74LS

74L series, low power, slower than original.

74AC series, Texas Instruments "advanced CMOS", low power, 74S speeds.

74F series, Fairchild "fast" series, similar to 74S speedwise, but lower power.

There are others that aren't too widely used.

>
> Thanks!
>
> Kurt
>
> > On Thu, 10 May 2001 08:54:17 -0700, you wrote:
> >
> > >Where did you get the 74sc374's that buffer the data. I have been looking
> > >for them for quite a while and have had no luck finding them.
> >
> > The 74SCxx series was the precursor to the 74HC and HCT series - if
> > memory serves, it was one of TI's lines, and the SC designation came from
> > combining the 74Cxx (meaning pinout-compatible CMOS versions of standard
> > 7400 TTL packages) and 74Sxx (speedier versions) designators. In other
> > words, "Speedy CMOS". :) (At the time, IIRC, the most common CMOS logic
> > family was the 4000 series, which was significantly slower than the 7400
> > TTL chips.)
> >
> > Depending on the circuit, you should be able to substitute either a
> > 74HC-series or a 74HCT-series chip for any of the old 74SC parts. (The
> > difference is that 74HC is compatible, signal and voltage-wise, with 4000
> > and 74C-series CMOS; 74HCT is compatible with regular 5-volt TTL logic.) I
> > forget whether the SC's were CMOS-level or TTL-level, so check your
> > schematic to see what other chips are connecting to it. :)
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Received on Sat May 12 06:16:34 2001