From: D. C. Sessions (email@example.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 <firstname.lastname@example.org> --------------+
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This archive was generated by hypermail 2b29 : Thu Jun 21 2001 - 10:11:47 PDT