ECL: Why'd they use negative voltages?
in [Design]
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From: John Larkin on 7 Jun 2010 20:47 On Mon, 07 Jun 2010 19:43:49 -0500, "krw(a)att.bizzzzzzzzzzzz" <krw(a)att.bizzzzzzzzzzzz> wrote: >On Mon, 7 Jun 2010 17:35:05 -0700, "Joel Koltner" ><zapwireDASHgroups(a)yahoo.com> wrote: > >><krw(a)att.bizzzzzzzzzzzz> wrote in message >>news:4e3r065vr383q2hc9fiuhre2mu9opopbai(a)4ax.com... >>>>And why 5.2V anyway? (Granted, 5.2V is no stranger than 6.3V filament >>>>transformers, I suppose...) >>> >>> Stack up the voltages (don't forget the AND gate). >> >>Purportedly it'll run down to around VCC-VEE = 3V and up to about 8V before >>you start seeing massive performance differences. 5.2V is certainly pretty >>close to the center of those two... hmm... I wouldn't be surprised if that's >>how they came upon it! > >No, Jim had the reason above. Try an AND gate at 3V. ;-) MC10EP05. John
From: krw on 7 Jun 2010 20:50 On Mon, 07 Jun 2010 17:41:37 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Mon, 07 Jun 2010 19:27:41 -0500, "krw(a)att.bizzzzzzzzzzzz" ><krw(a)att.bizzzzzzzzzzzz> wrote: > >>On Mon, 7 Jun 2010 16:56:24 -0700, "Joel Koltner" >><zapwireDASHgroups(a)yahoo.com> wrote: >> >>>I realize it was the early '60s and all, but why does ECL generally use 0V for >>>VCC and -5.2V for VEE, rather than, oh, say... 5V for VCC and 0V for VEE? >>>Something related to how things were done when toobs ruled? (I realize that >>>you can almost always run ECL off of 5V/0V -- and apparently this was popular >>>practice at one time?) >> >>Add to the above, shorting the common emitter outputs to ground isn't >>damaging. >> >>>And why 5.2V anyway? (Granted, 5.2V is no stranger than 6.3V filament >>>transformers, I suppose...) >> >>Stack up the voltages (don't forget the AND gate). >> >>Not all ECL was the same, though. Our high performance ECL ran off +1.25V and >>-3V, with the outputs around ground. > >+2 and -3 allow terminations to ground. Terms are where most of the >power goes. +1.25 makes the reference ground. The termination voltage was -.7V. The power was mitigated by offsetting the whole supply stack.
From: Joel Koltner on 7 Jun 2010 20:50 "D Yuniskis" <not.going.to.be(a)seen.com> wrote in message news:huk3tl$224$1(a)speranza.aioe.org... > Dunno. But, it was fast and ate gobs of power. In the > mid 70's I worked on a processor (i.e., what nowadays > would be a CPU "chip") that drew 100A (MECL III and 10K). > "Bus bars" for power were 3/4" square copper shafts. *Most* impressive. :-) > If you "slipped" when pulling/installing a chip, the legs > would vaporize before the power supply would even hiccup. > (needless to say, you removed all jewelry -- belt buckles, > eye glasses, rings, etc. -- when working on it) --> http://sound.westhost.com/project117.htm (a 1500W audio amplifier, "It is capable of destroying any loudspeaker connected to it, regardless of claimed power rating.") :-)
From: krw on 7 Jun 2010 20:51 On Mon, 7 Jun 2010 17:44:55 -0700, "Joel Koltner" <zapwireDASHgroups(a)yahoo.com> wrote: >Thanks John, that's quite informative. > >"John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in message >news:di3r0613v9lkk2p8dq06snde2hgopt87fr(a)4ax.com... >> Newer stuff, like EclipsLite, works at 3.3 volts, and some at 2.5. I >> do mixed-mode PECL and cmos/FPGAs off a +3.3 volt supply. > >That's kinda what prompted the question -- Joerg has been pointing me at some >of the high-speed logic from the likes of Micrel, and I was reading up some in >the old MECL System Design Handbook so that I hopefully won't embarrass myself >too badly when I go to use some of it. :-) Cool stuff. ...and easy to use.
From: Joerg on 7 Jun 2010 20:54
Joel Koltner wrote: > Thanks John, that's quite informative. > > "John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in > message news:di3r0613v9lkk2p8dq06snde2hgopt87fr(a)4ax.com... >> Newer stuff, like EclipsLite, works at 3.3 volts, and some at 2.5. I >> do mixed-mode PECL and cmos/FPGAs off a +3.3 volt supply. > > That's kinda what prompted the question -- Joerg has been pointing me at > some of the high-speed logic from the likes of Micrel, and I was reading > up some in the old MECL System Design Handbook so that I hopefully won't > embarrass myself too badly when I go to use some of it. :-) > If you have the old MECL databooks treasure them, don't let them end up in the recycling. Both Motorola and Fairchild did a most excellent job explaining stuff in there and I assume many of the authors are no longer with us on earth. If you do a good job bypassing the supply and keeping leads short there isn't much that can go wrong. Except for one thing: Some series have only half the logic swing and that almost bit me once. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |