ken@turtlevax.UUCP (Ken Turkowski) (09/29/84)
Myriad new high-speed CMOS IC's are coming out from lots of new
startups as well as some of the old fogies. AMD, Analog Devices,
Cypress, Integrated Device Technology (IDT), International Microcrcuits
(IMI), Lattice, Logic Devices, TRW all have LSI devices (memories,
processing units), pending or available. Other companies, such as
National, TI, Zytrex, RCA, have got high-speed CMOS MSI chips
(registers, gates, decoders, etc.).
It almost seems like it is near the time when a design may consist
entirely of CMOS components.
How close is high-speed CMOS to price parity with S or LS? Some of the
components (MSI) are dominated by packaging costs, so should be no more
than 5% more expensive than their bipolar counterparts. How about LSI
components?
--
Ken Turkowski @ CADLINC, Palo Alto, CA
UUCP: {amd,decwrl,flairvax,nsc}!turtlevax!ken
ARPA: turtlevax!ken@DECWRL.ARPApadpowell@wateng.UUCP (PAD Powell) (09/30/84)
The decisions about LS/S/CMOS have to be made on an individual basis.
Currently, it seems to be fairly obvious that ordinary TTL is dead or
dying. LS TTL will usually make do for "slow", ie.- < 10 Nsec, things,
S is safer if you need speed and margins. Lately I have been observing that
S power consumption seems to be going down, while speed is staying the same.
Any comments on this?
As for CMOS: the curse of CMOS seems to be its limited drive capability.
If you run CMOS at 5V, it is usually in the 50-100 Nsec range
(you know what I mean), and that is pretty good for lots of things. I have
seen specs about some new CMOS drivers that look incredible, but I have not
investigated them personally.
I have also vicious things to say about CMOS latchup problems. I have just
spent a little time discovering that a major failure mode was being caused by
the separate supplies on different portions of the system to ramp at
different rates. The CMOS board came up after the LS board,
and with about 20% probability, at least one part on it would latch up.
GRRRRR.... The fix to this problem was not trivial.
Patrick ("CMOS! FLIP-FLOP! BIT! BIT! BIT!") Powellken@turtlevax.UUCP (Ken Turkowski) (10/05/84)
> How close is high-speed CMOS to price parity with S or LS? Some of the > components (MSI) are dominated by packaging costs, so should be no more > than 5% more expensive than their bipolar counterparts. How about LSI > components? The new (October 4, 1984) Electronic Design has several articles on CMOS technology, including: * Technology Report: CMOS seeks to dominate the digital world * Technology Report: Analog CMOS driven by need for mixed circuitry * The future of CMOS: Twelve experts tell how CMOS will blossom * Six leading-edge CMOS IC's bring new sparkle to system design -- Ken Turkowski @ CADLINC, Palo Alto, CA UUCP: {amd,decwrl,flairvax,nsc}!turtlevax!ken ARPA: turtlevax!ken@DECWRL.ARPA
paul@dual.UUCP (Baker) (10/11/84)
> Myriad new high-speed CMOS IC's are coming out from lots of new > startups as well as some of the old fogies. AMD, Analog Devices, > Cypress, Integrated Device Technology (IDT), International Microcrcuits > (IMI), Lattice, Logic Devices, TRW all have LSI devices (memories, > processing units), pending or available. Other companies, such as > National, TI, Zytrex, RCA, have got high-speed CMOS MSI chips > (registers, gates, decoders, etc.). Most of these high-speed CMOS circuits appearing seem to be about half the speed of LS parts. It is is a bit hard to tell as many of the CMOS manufacturers only publish "typical" specifications. These are quite useless for design purposes as you are not guaranteed to only get "typical" parts. They do appear to be quite useful for slow speed parts of circuits which are not connected to external buses, where it is desirable to conserve power. In looking at retrofitting some of my existing designs, it is surprising just how few parts are candidates for this. Zytrex did have a lot of double page advertisements headed "Who killed Schottky dead?", with, as usual, no indication of the parts they produced. After many further enquiries, it turns out there are supposed to be two speed selections, one about as fast as LS the other about as fast as S. The second are completely unavailable and I'm still waiting for samples of some the first types. > It almost seems like it is near the time when a design may consist > entirely of CMOS components. Not for a few years yet I think. Where CMOS will do very well is in the area of gate arrays and other large scale circuits. It appears that most of the slowness of the current high-speed CMOS is in the output buffers. Also the range of parts available in high-speed CMOS is very much smaller than for LS or S or even F series of TTL. This is particularly noticeable if attempts are made to get parts. At the moment many 20 pin, 8 bit parts are available (HCT373, HCT244, etc). I believe HCT00s and simple parts are also available, but you do not reduce power consumption much with these as the simple LS parts do not consume much anyway. I am still having trouble getting samples of HCT174s and HCT393s - not exactly high-tech but not exactly available either. > How close is high-speed CMOS to price parity with S or LS? Some of the > components (MSI) are dominated by packaging costs, so should be no more > than 5% more expensive than their bipolar counterparts. How about LSI > components? Nearly all parts costs are dominated by "what the market will bear" rather than by any real costs of manufacture. At the the moment high-speed, or as I call them High-Cost, family of CMOS parts seem to cost about three times the equivalent LS parts, sometimes more. For example a 74LS670 has a cost of about 70 cents. I was quoted about $5.00 for a CMOS TTL compatible version. Another thing to consider is that many of the less common parts are only made by one manufacturer, sometimes a rather obscure one. Purchasing departments tend to give engineers a hard time about specifying parts like this. Paul Wilcox-Baker.