RE: [IBIS-Users] 3.3V I/O, 5V tolerant

From: Abril, Giovanni \(Space Technology\) <giovanni.abril_at_.....> Date: Sun Dec 18 2005 - 09:52:36 PST · This archive was generated by hypermail 2.1.8 : Sun Dec 18 2005 - 09:58:06 PST

Thanks for your response Tom.

The part has a 2.5V core and 3.3V i/o voltage.  Changing the voltage reference, would mean my 3.3V rail gets set to 5V.  Is that how it should be done?  Also, I think s2ibis ignores my rising/falling waveform fixture values (of 3.3, 3.0, 3.6) and sets them to 5.0, 4.5, and 5.5V.

-----Original Message-----
From: Tom Dagostino [mailto:tom@teraspeed.com]
Sent: Saturday, December 17, 2005 4:53 PM
To: Abril, Giovanni (Space Technology); ibis-users@eda.org
Subject: RE: [IBIS-Users] 3.3V I/O, 5V tolerant

I'd change it to:

Voltage Ref: 5.0 4.5 5.5
Pulldown Ref: 0 0 0
Pullup Ref: 3.3 3.0 3.6
Power Clamp Ref: 5.0 4.5 5.5
GND Clamp Ref: 0 0 0

Tom Dagostino
Teraspeed(R) Labs
13610 SW Harness Lane
Beaverton, OR 97008
503-430-1065
tom@teraspeed.com
www.teraspeed.com

Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
401-284-1827

-----Original Message-----
From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org]On
Behalf Of Abril, Giovanni (Space Technology)
Sent: Saturday, December 17, 2005 12:54 PM
To: ibis-users@eda.org
Subject: [IBIS-Users] 3.3V I/O, 5V tolerant

Hello IBIS experts,

I'm creating a model from HSPICE using S2IBIS2 vers. 2.1 and have a
question.

If my buffer is 3.3V i/o, but is 5V tolerant, and am using:

Voltage Ref: 3.3 3.0 3.6
Pulldown Ref: 5.0 4.5 5.5
Pullup Ref: 0 0 0
Power Clamp Ref: 5.0 4.5 5.5
GND Clamp Ref: 0 0 0

I was thinking this should vary my voltages from -5V to 10V for the clamps,
but it does not.  It instead varies from -Vcc to 2Vcc as usual.

Is this how I should be setting this up?

Thanks,
Gio

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