[SI-LIST] Re: IBIS model generation from Datasheet? How?
- From: "Tom Dagostino" <tom@xxxxxxxxxxxxx>
- To: <imsong@xxxxxxxxxxxxxx>,"'Signal Integrity Mail Group'" <si-list@xxxxxxxxxxxxx>
- Date: Tue, 29 Oct 2002 20:06:13 -0800
Making an IBIS file from a datasheet will not get you a very accurate model.
Of all the ways of making an IBIS file it is the least preferred. Using the
Vol and Voh specs at the currents specified will produce a very weak/higher
impedance output buffer than the part is in reality for 99% of the
components out in the real world. The current specs in datasheet are
typically one third to one tenth the actual currents you will see in typical
parts. Also two data points will give you a straight line IV curve where
most buffers show saturation effects. Most datasheets do not tell you about
power clamps though the lack of them can be inferred from statements like "5
volt compatible".
You usually do not have any data in a datasheet that gives you the rise and
fall time for the ramp section and no data at all for the VT tables.
Unless you are doing very, very crude simulations this method will lead you
down a rosy path to problems. It is not recommended.
Tom Dagostino
Device Modeling Division
Teraspeed Consulting Group LLC
2926 SE Yamhill St.
Portland, OR 97214
(503) 430-1065
tom@xxxxxxxxxxxxx
http://www.teraspeed.com
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Inmyung Song
Sent: Tuesday, October 29, 2002 4:14 PM
To: Signal Integrity Mail Group
Subject: [SI-LIST] IBIS model generation from Datasheet? How?
Hi everyone.
One of my big problem is making IBIS model from Datasheet and fixing it from
that.
Is there anybody that make it clear?
Specially, in I/V curves often have a problem.
As I know, the I/V curves are the information of Buffer strength and
Input/output impedance.
That means if I have only two(V and I) points, I can make I/V curve, is it
right?
For example when Vil = 0.8V and Vih = 2.0V and Vcc = 3.3V, if I have the
data
such as when Vol = -3.3V the Iol = -50mA and Vol = 6.6V the Ioh = 100mA,
>From this information, Can I make the V/I curve?
Any comment is O.K. to me.
Thank you very much.
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