Subject: Re: [IBIS-Users] IBIS VMEAS and VREF Question.
From: Tessa Trethewey (tnt@cypress.com)
Date: Fri Jun 20 2003 - 11:00:32 PDT
Hi Rick
Question: is the Vmeas Vcc-relative? While the voltage of the part is varied over Vmin to Vmax, the
Vref and Vmeas are held constant and this can cause the error you mention.
If you use the [Model spec] keyword you can give Vmeas min, typ and max values so it follows your
Vcc from Min to max. Apparnatly some simulators will also allow Vref to be defined this way, but I
got errors in the Vis. IBIS editor 3.0 so check your particular simulator.
EG:
[Model] CMLOUT
Model_type Output
Polarity Non-Inverting
Enable Active-High
Vref = 2.6V
Cref = 0pF
Rref = 50
C_comp 1.8305pF 1.6406pF 1.9862pF
[Model spec]
Vmeas 2.6 2.45 2.75
|Vref 2.6 2.45 2.75
Hope this helps!
Tessa Trethewey
Cypress Applications Engineering
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