Subject: Re: [SI-LIST] : How board over-shoot under-shoot influence a chip.

Jon Powell (jonp@pacbell.net)
Sun, 21 Mar 1999 20:13:47 -0800

Yehuda,
One problem with excessive overshoot is the possibility of latch-up in
certain devices which can cause physical damage to the components. Many
devices have diode protection from overshoot but the exact amount the
devices can
tolerate is not necessarily stated. Most devices have a Max Overvoltage
specification, however they seldom specify pulse immunity and such.

regards,
Jon Powell
Viewlogic Consulting Services.

Yehuda D. Yizraeli wrote:

> Hello SI experts,
>
> Its good design practice to have a non reflective board design, however i
> would like to understand the nature of the failure caused by the reflections.
>
> One failure mechanism is double triggering, but assuming the reflections acuse
> an overvoltage (over the power supply value, or under ground value) BUT not ringing through
> thetriggering point, how can a chip be affected by this ringing....? Does it make the input
> buffer levels lower (hey hey hey, its spikes, short term influence, doesn't it???).
>
> Any help, article and/or any pointer is appreciated.!!
>
> regards, yehuda
>
> --
> -------------------------------------------------------------------
> Yehuda D. Yizraeli
>
> Zoran Microelectronics Ltd. E-mail: yehuda@zoran.co.il
> Advanced Technology Center Direct Tel: 972-4-85-45-795
> P.O.B. 2495, Haifa 31204, Israel Operator : 972-4-85-45-777
> http://www.zoran.com Fax : 972-4-8-551-550
> -------------------------------------------------------------------
>
> In god we trust, all the rest should use data
>
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> The trouble with doing something right the first time is that
>
> nobody appreciates how difficult it was.
>
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

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