ECL: Why'd they use negative voltages?
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From: Jim Thompson on 9 Jun 2010 10:55 On Wed, 09 Jun 2010 09:52:11 +0200, Uwe Hercksen <hercksen(a)mew.uni-erlangen.de> wrote: > > >Joel Koltner schrieb: > >> 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?) > >Hello, > >I saw a design using ECL and TTL logic together. For easier interface >between ECL and TTL they used +5,2 and 0 V for ECL ICs. Only very few >ECL logic was used. > >Bye There used to be a translator chip, ECL (on -5.2V) to TTL (on +5V)... really easy to do if you do it all with currents. My MC4024 "TTL" Multivibrator actually has an ECL current-mode cross-coupled oscillator that is level-shifted to TTL. Some data sheets still show the schematic (see my website for a schematic from a 1973 data-book). ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | The only thing bipartisan in this country is hypocrisy |