Subject: RE: [IBIS] IBIS generation w/ two power supplies
From: Muranyi, Arpad (arpad.muranyi@intel.com)
Date: Thu Apr 24 2003 - 17:38:16 PDT
Wil,
It sounds that your pullup's reference voltage is programmable,
correct?
In that case, you should use the model selector and make two
models, on with [Pullup Reference] = 3.3 V, and the other with
[Pullup Reference] = 5 V.
Arpad Muranyi
Intel Corporation
=============================================================
-----Original Message-----
From: Wil Ngan [mailto:wngan@idt.com]
Sent: Thursday, April 24, 2003 4:54 PM
To: ibis@eda.org; ibis-users@eda.org; ibis-info@eda.org
Subject: [IBIS] IBIS generation w/ two power supplies
hi,
I'm trying to generate an ibis file from a circuit with two power
supplies, vcc and vccq. Vcc is fixed at 5v, while vccq is either 3.3 or
5v, depending on what we would like the output high to be. How do I
going about doing this?
In the past, I've used [Pullup reference], [Power clamp reference] to
set vcc to 5v, vccq to 3.3v, respectively. However, I just realized
that I cannot set vccq using [power clamp reference], since there's
actually
NO power clamp in my circuit. (The ckt only has ground clamp
transistors, which protects the device from overly low input voltages,
at same time, that
same device works to protect high input voltages through breakdown.) I
had been generating [Power clamp] current table while in fact there is
no power clamp circuit. Not good. Furthermore, this causes [Pullup]
current table to be wrong, since [Pullup]currents = I(pullup generated
by hspice) - I(power clamp), so the numbers in my [Pullup] table are
actually lower than they should be.
So, going back to the original question, without using [Pullup
reference] or
[Power clamp reference], how should I go about in providing two power
supplies to this circuit to generate ibis file?
- Wil
idt sram, 408/330-1623.
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