5 Nov
2011
5 Nov
'11
2:12 p.m.
On Nov 4, 2011, at 6:42 PM, Tony Duell wrote:
I thought that 74HCT were 5V-only parts (somethign like a 5.5V maximum).
74HC was wider (up to 6 or 7V, and down to about 2V). The 4000 series
are a lot wider.
And I think (without checking the databooks) that
4000 series will stand
a higher supply voltage thea 74HCxxx
My recollection is that the 74HCxxxxx are nominal 5V parts (the HCT
ones specifically run with TTL switching thresholds). CD4000 series is
full range, I think usually 3.3-15v or thereabouts, with the switching
threshold usually at 0.5Vdd. 74HC was generally considerably slower than 74F for
the same part
(though also took WAY less power), 74HCT slower still.
I didn;t think there was taht much speed difference between 74HC and
74HCT. I will have to check the data books agian. And yse, 74F (and
74AS) is the fast one...
400 series CMOS will go up to 15 or 18V (depending on the version) I
think. This led to a lot of car-related projected in UK magazines which
ran 400 series CMOS chips straight off the car battery.
They are slow, and thus are not commonly used in
classic computers. The
odd oens do turn up, particualrly where speed is not very important but
he function was (IIRC ,the BCD interface for my HP9815 calculator has
some odd 4000 series shift registers in it, there is no direct TTL
equivalent,
And I sure love the 405x series of (basically) analog multiplexers and
4016 analog switches. By now there are a number of better analog
multiplexers and switches out there, but there weren't any straight TTL
muxes that I remember which operate in both directions (because they
were typically combinational logic instead of pass gates).