Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!cica!gatech!emory!stiatl!john
From: john@stiatl.UUCP (John DeArmond)
Newsgroups: sci.electronics
Subject: Re: How can I turn on this bulb with TTL?
Message-ID: <5926@stiatl.UUCP>
Date: 20 Jul 89 18:22:36 GMT
References: <4363@merlin.usc.edu> <3868@phri.UUCP> <5841@stiatl.UUCP> <561@sjs.sj.ate.slb.com>
Reply-To: john@stiatl.UUCP (John DeArmond)
Organization: Sales Technologies Inc., "The Procedure IS the product"
Lines: 21

In article <561@sjs.sj.ate.slb.com> storkamp@sjs.sj.ate.slb.com (Mark Storkamp, 408-998-0123 (ex 2079)) writes:
>
>My TI data book shows, for the 7404, maximum high-level output current as
>-400uA. Somebody has sugested using a 74Hxx part, this has only -500uA.

Don't confuse the current specification an output can supply and stay within
the TTL voltage specs with the maximum available output current.  TI may not
even specify this value.  When driving a transistor, we are interested in
the current drive and not the voltage as long as the driver can supply at 
least 0.6 volts or so.  To moot this question, I actually measured the
output while driving a diode (same as B-E junction).  The non-descript gate
I pulled from a grab-bag supplied 25 ma into a 0.6v load.  Not spec but not
bad.

John


-- 
John De Armond, WD4OQC                     | Manual? ... What manual ?!? 
Sales Technologies, Inc.    Atlanta, GA    | This is Unix, My son, You 
...!gatech!stiatl!john    **I am the NRA** | just GOTTA Know!!!