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

From: Akhilesh CHANDRA <akhilesh.chandra_at_.....>
Date: Wed Apr 27 2005 - 21:40:37 PDT
Hello Bob,

  Yes, I think ELDO and HSPICE override voltage range while in HYPERLYNX 
it does't, befor this I validate my models through ELDO and HSPICE now I 
switch to HYPERLYNX and find out this problem .
  In HYPERLYNX if keyword voltage range, power Clamp Reference and 
Pullup Reference are presents then it take volatge range keywords for 
simulation. In my view if optional keywords are present then it should 
read from optional keywords.

Regards
Akhilesh

Bob Ross wrote:

> 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
>>
>
>>
>>
>


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Received on Wed Apr 27 21:40:55 2005

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