Subject: RE: [IBIS-Users] FW: Extreme currents????
From: Jon Powell (jpowell@innoveda.com)
Date: Wed Jul 10 2002 - 15:56:42 PDT
I agree with everybody,
That warning is primarily there to let you know that you have an ideal diode
and not a physical one
(that has some resistance and so will current limit itself).
Most simulators do pretty much the right thing when the see this, though I
am sure the "right thing" is
slightly different in all cases.
jon
> -----Original Message-----
> From: Muranyi, Arpad [mailto:arpad.muranyi@intel.com]
> Sent: Wednesday, July 10, 2002 3:33 PM
> To: ibis-users@server.eda.org
> Subject: RE: [IBIS-Users] FW: Extreme currents????
>
>
> I don't think this is so much of an issue of how high the
> tools can go as Lynne stated. A number is a number,
> regardless of how high it is... (Aside from the precision
> variations you run into depending on the number of bytes
> used for the numbers).
>
> The real problem in my opinion is that if you have a diode
> that does this, it will clip an overshoot, which may be
> different from what a real device does, and you will see
> waveforms that are incorrect.
>
> Arpad Muranyi
> Intel Corporation
> =============================================================
>
> -----Original Message-----
> From: Lynne Green [mailto:lgreen@cadence.com]
> Sent: Wednesday, July 10, 2002 3:19 PM
> To: Chris.Dewitt@motorola.com; ibis-users@eda.org
> Subject: re: [IBIS-Users] FW: Extreme currents????
>
>
> Hello, Chris,
>
> Different EDA tools have different upper limits on currents
> that can be
> handled
> by the simulator.
>
> The warning is needed because "Spice" models that use the
> default series
> resistance (0.0 ohms) for diodes and junction leakage
> currents result in
> large
> IBIS table currents (often above 1 MegAmp). Most EDA tools
> don't go quite
> _that_ high.
>
> Best regards,
> Lynne
>
>
>
> -----Original Message-----
> From: John Angulo [mailto:jangulo@innoveda.com]
> Sent: Tuesday, July 09, 2002 6:02 PM
> To: ibis-users@eda.org
> Subject: [IBIS-Users] FW: Extreme currents????
>
>
> The following is forwarded on behalf of Chris DeWitt at Motorola TCG.
> Please send all private replies to Chris.Dewitt@motorola.com.
>
> John Angulo
> IBIS Open Forum Postmaster
> -----------------------------------
>
> If I run IBISCHK3 on many models I download I get an "Extreme currents
> present" warning.
>
> What are the limits on currents in the VI tables? I can't find it
> documented anywhere.
>
> Thanks
>
> Chris DeWitt
> Principal Staff Engineer
> Motorola TCG
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