> -----Original Message-----
> From: Jan-erik S=F6derholm (QAC) [SMTP:Jan-erik.Soderholm@PAC.ERICSSON.SE]
> Sent: Tuesday, April 29, 2003 3:14 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: [EE]: output from schmidt trigger less than 5V
>=20
> Mike Harrison wrote:
> > Use HCMOS instead - LSTTL is completely obsolete, as HCMOS
> > is better in all respects (speed, power, cost).
>=20
> Is that so ?
> Power yes, cost maybe, but speed ?
>=20
> From what I'v seen bipolar 74xxx is still faster then CMOS 74xxx.
>=20
> From the "Texas Digital Logic Pocket Data Bbook" :
>=20
> 74xx00, switching time (low to high):
>=20
> 7400    :  22   ns
> 74LS00  :  15   ns
> 74ALS0  :  11   ns
> 74AS00  :   4.5 ns
> 74F00   :   6   ns
>=20
> 74HC00  :  25   ns
> 74HCT00 :  30   ns
> 74ACT   :  12.3 ns
>=20
> Jan-Erik S=F6derholm
>=20
If you want speed then the AHC(T) series is considerably faster and still
consumes a fraction of the current of an LS device=20

Regards

Mike


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