Accelerated Graphics Port Interface Specification

AGP3.0 Interface Specification
Rev. 1.0
89
/ NOTE
1. The min current limit is relaxed above Vswing to accommodate a standard CMOS transistor
saturation characteristic. Termination impedance tolerance above Vswing becomes less
important for signal integrity purposes.
2. Equations A and B reflect a ± 10% tolerance over the entire set of pull-down and termination
impedance, across the range from 0 Volts to Vswing. Any single buffer is required to limit its
impedance variation to within a 10% total variation, although it may reside anywhere within the
overall 20% of tolerance described by the ± 10% region.
Figure 3-21: V/I Curve for AGP3.0 Receiver Termination Device
0.0 0.2 0.4 0.6 0.8 1.0
V
OUT
(Volts)
I
OUT
V
Swing
Pull-down
Range
V
Swing
1.1*Z
Targ
50+10%
Pull-down and Terminator
V Swing
0.9*Z Targ
50-10%