Re: [IBIS-Users] difference between [Pullup Reference] and [Voltage Range]

Hello Akhilesh:

In some tool, the [Pullup Reference] and/or the [Power Clamp Reference]
will override the [Voltage Range].

Bob

Tom Dagostino wrote:

> IBIS voltages only are concerned with the voltage applied to the output or
> input stage (that may be changing with some of the new birds being
> discussed).  They define which rail, voltage, the currents will flow into or
> out of.  For an output the Voltage Range key word will tell the simulator
> what supply voltage the output's pullup will supply current from and what
> supply voltage the power clamp if present will dump current into.  If there
> is a Pullup Reference and a Powerclamp Reference stated in the model then
> first, they describe the power supply that sources current for the pullup
> and power supply that sinks current for the clamp.  In this case the
> Powerclamp Reference and be different than the Pullup Reference.  A good
> example of this would be a 3.3V output buffer (Pullup Reference) that is 5
> Volt compatible with a Powerclamp Reference of 5.0 Volts.
> 
> It is unlikely that your example would ever occur.  If your Pullup Reference
> is 2.5V your Voltage Range, the operating is not 1.2 Volts.  The core supply
> voltage should not be in the model, it is not sinking or sourcing currents
> in the input or output stage.
> 
> Tom Dagostino
> Teraspeed Labs
> 13610 SW Harness Lane
> Beaverton, OR 97008
> 503-430-1065
> http://www.teraspeed.com
> tom@teraspeed.com
> 
> Teraspeed Consulting Group LLC
> 121 North River Drive
> Narragansett, RI 02882
> 401-284-1827
> 
> Teraspeed is the registered service mark of
> Teraspeed Consulting Group LLC
> 
> -----Original Message-----
> From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org]On
> Behalf Of Akhilesh CHANDRA
> Sent: Thursday, April 21, 2005 6:56 AM
> To: ibis; ibis-users
> Cc: Akhilesh CHANDRA
> Subject: [IBIS-Users] difference between [Pullup Reference] and [Voltage
> Range]

> 
>>
> Hello Friends,
> 
>  As I read in IBIS standard
> 
> Voltage Range----Defines the power supply voltage tolerance over which
> the model is intended to operate.
> Pullup Reference--Defines a voltage rail other than that defined by the
> [Voltage  Range] keyword as the reference voltage for the [Pullup] I-V
> data.
>   My buffer have dual supply VDD and VDDE2V5. VDD is the core side
> supply and VDDE2V5 voltage at the pad as well as voltage at the pullup
> and power clam diode.
> 
>  I wnat to know how this information is use in the simulation.
>  When pullup information is present then it's overwrite voltag information?
> 
> I have given
> [Voltage Range]  1.2 1.1 1.3
> [Pullup Reference] 2.5 2.2 2.7
> 
>    Which information is used in the simulation.
> 
> Regards
> Akhilesh
> 

> 
> 

-- 
Bob Ross
Teraspeed Consulting Group LLC     Teraspeed Labs
121 North River Drive              13610 SW Harness Lane
Narragansett, RI 02882             Beaverton, OR 97008
401-284-1827                       503-430-1065
http://www.teraspeed.com           503-246-8048 Direct
bob@teraspeed.com

Teraspeed is a registered service mark of Teraspeed Consulting Group LLC


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