Path: utzoo!utgpu!water!watmath!clyde!rutgers!cmcl2!nrl-cmf!ames!amdcad!sun!pitstop!sundc!seismo!uunet!mcvax!diku!dde!mbe
From: mbe@dde.uucp (Martin Berg)
Newsgroups: sci.electronics
Subject: Re: TTL (and other) families
Summary: More on HCT (was TTL families...)
Message-ID: <143@Giraf.dde.uucp>
Date: 18 Jan 88 17:38:32 GMT
References: <2040@navajo.UUCP> <1457@sigma.UUCP>
Organization: Dansk Data Elektronik A/S, Herlev, Denmark
Lines: 27


In article <1457@sigma.UUCP> bill@sigma.UUCP (Willian Swan) writes:

> Also note that 74HCT parts will consume *much* more current when driven...

There is another problem when using this family of TTL.:

Last when I read TI's specifikations on the 74HCT family, it was made   
clear that this family needed at least 4.5 V supply voltage.

Therefore you should not use these parts (for reliable operation)
in applications with a low-voltage, low-power standby mode (f.ex.
for preserving contents of CMOS-RAM). (Ok, Ok: I'am just reading the
specifications ;-) );

I have some times seen this done in memory-makers application notes as
a way to seperate the CMOS-memory (with standby power) from the rest
of the system (with more-or-less standard bipolar TTL parts).

My question is: Has the specifications changed or are these parts
better than promised ?

-- 

Martin Berg      mcvax!diku!dde!mbe
                    or
                 mbe@dde.UUCP