Re 2: Revised proposal on MSE high-impedance spec

John Lohmeyer lohmeyer at
Mon Jun 21 13:06:37 PDT 1999

* From the T10 Reflector (t10 at, posted by:
* John Lohmeyer <lohmeyer at>
At 6/21/99 12:56 PM , Gene_Milligan at wrote:
>I think we still are disconnected. My issues is whether or not the input
>can be that high not whether or not it can be sourced.


Oh.  If you are concerned about how much current the inputs can safely sink
then you have a design choice.  You are not required to sink >10 mA.  You
are only required to not operate in the shaded area.  You can continue to
meet the existing +- 20 uA specification if you want to.  

All this proposal was intended to accomplish was to relax the + 20 uA
specification above 3 volts for the benefit of those designers that plan to
use 3-volt processes.  When the input signal goes above Vdd, these devices
typically shunt the input signal to Vdd drawing far more than 20 uA.  Wally
pushed for the 100 Ohm slope to minimize signal reflections in this situation.


John Lohmeyer                  Email: lohmeyer at
LSI Logic Corp.                Voice: +1-719-533-7560
4420 ArrowsWest Dr.              Fax: +1-719-533-7036
Colo Spgs, CO 80907              BBS: +1-719-533-7950

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