Re: [SI-LIST] : response to semiconductor I/O edge rates

Dennis Tomlinson (
Thu, 15 Jul 1999 17:04:35 -0500

<soap box>
Perhaps what is needed is not a continuously variable slew rate
covering orders of magnitude in range, but something much more
restricted, possibly binary programmable (per device, or per driver),
and hopefully easier to implement.
</soap box>

Just my $0.02,


Muranyi, Arpad wrote:
> I would like to reiterate an earlier response by someone.
> With many chips one big problem is that even if the semiconductor vendors
> go out of their way and put slew rate controlled buffers into their
> products,
> there is no way to tell how fast the product will actually run in a
> particular
> design. This is especially true for glue logic chips which can be used in a
> 1 MHz system just as well as in a 100 MHz system. How should the IC vendor
> adjust the slew rate then? It will have to be externally programmable then,
> which adds more design complexity, and will raise the cost of the part.
> Are people be willing to pay that extra cost in large quantities? Even if
> the answer is yes, an SI engineer will still be needed to determine
> the optimal setting of the slew rate for the particular design.
> Arpad Muranyi
> Intel Corporation
> ========================================================================
> -----Original Message-----
> From: Roy Leventhal []
> Sent: Thursday, July 15, 1999 8:47 AM
> To:
> Subject: Re: [SI-LIST] : respons to semiconductor I/O edge rates
> All,
> I have really appreciated the ongoing discussion about edge rates that my
> original beef has kicked up and the many related topics it has opened up.
> Lest we loose sight of my original beef it is this:
> A consequence of shrinking feature size to get more on a die and faster
> processing speeds is this: Edge rates have been kicked into warp speed: This
> has
> lead most boards potentially having a signal integrity problem on every net
> on
> the board --> where the edge rate bears no relation - way too fast - to the
> intended application it creates "make work" unneccesary problems that cuts
> into
> his/her chances of competitive success.
> So long as SI engineers don't understand this and don't push back on their
> suppliers to see if the problem can be fixed at the SOURCE, they don't
> understand that they're hired to make a contribution, not engage in busy
> work.
> Roy
> Roy

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