[SI-LIST] Strange Gnd Clamp V-I curve when generating IBIS
- From: "Rohan Hubli" <Rohan.Hubli@xxxxxxxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Tue, 14 Dec 2004 15:39:53 -0800
Hi all,=20
I am generating a IBIS model for one of our chips and am facing a =
strange problem when generating=20
the GND Clamp data.=20
On plotting the V-I data, the GND clamp turns on correctly at one diode =
drop below 0v (i.e. -0.7v). And the
current increase linearly as the voltage is swept across -Vcc. But on =
+ve voltage sweeps towards +2 Vcc the=20
current starts to increase linearly again around +2.5v. I was under the =
assumption that the current should=20
remain almost flat and negligible for voltages from 0v to 2Vcc as the =
GND Clamp should not be in effect.
Here are the I/O pad details : =20
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
#1. 0.18u. 3.3v (5v tolerant ), Bidir pad.=20
#2. Has pullup reference of 3.3v
#3. Power Clamp reference of 5V
#4. GND Clamp. PullDown reference of 0v
(PS : I am not the original designer for the pad in question. )
Could someone, explain why this is occurring ? And if this is acceptable =
for an IBIS model.=20
Thanks
Rohan =20
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List FAQ wiki page is located at:
http://si-list.org/wiki/wiki.pl?Si-List_FAQ
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
