Re: [SI-LIST] : Standard tolerance for 1.8V supplies

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From: D. C. Sessions (si-list@lumbercartel.com)
Date: Mon Apr 30 2001 - 09:04:57 PDT


On Monday 30 April 2001 07:02, Ingraham, Andrew wrote:

> The JEDEC standards for some 3.3V parts have a recommended operating range
> of 2.7 to 3.6V (= +9.1% / -18.2%). Some JEDEC standards for 2.5V parts
> specify +/-0.2V (= +/-8%), while another uses 1.8 to 2.7V (= +8% / -37%).
> JESD8-7 for 1.8V parts has both a "normal range" (1.8V +/-0.15V) and a "wide
> range" (1.2 - 1.95V).
>
> Know your data sheets!

Thanks for bringing up the "wide range" stuff. We're getting more and more of
those lately, mainly because there is a _lot_ of battery-operated circuitry that
doesn't need to push the performance; deep-submicron CMOS optimized for
density and power provides more than enough.

The hazard here is using wide-range specs for applications where performance
_does_ matter. As a rule, the wide-range specs are extremely sloppy to cover
performance degradation at low supply voltage and the I/O specs are totally
useless from an SI standpoint.

We're working on that -- there is absolutly NO excuse for specifying a minimum
drive strength that won't do reflected-wave on a 90-ohm line with first-incidence
receiver switching. There are some JC-16 members who are getting tired of
having me rant about SI-worthless specs, so it might help if more customers
did a little ranting of their own.

If you've got a Really Good Horrible Example that I can use for my next
tantrum, I'd love to hear it. Private reply is probably best.

-- 
| The race is not always to the swift, nor the battle to the strong. |
| Because the slow, feeble old codgers like me cheat.                |
+--------------- D. C. Sessions <dcs@lumbercartel.com> --------------+

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