
PRELIMINARY
163
A
PCIset Electrical Specifications
2.2
Signal Quality Specifications
Signals driven by any component on the Pentium Pro Processor bus must meet signal quality specifications to
guarantee that the components read data properly, and to ensure that incoming signals do not affect the long
term reliability of the components. There are three signal quality parameters defined: Overshoot/Undershoot,
Ringback, and Settling Limit. These parameters are discussed in the next sections.
2.3
PCIset Ringback Specification
This section discusses the ringback specification for the parameters in the GTL+ signal groups on the Intel
450KX/GX PCIsets.
Case A requires less time than Case B from the VREF crossing until the ringback into the “overdrive” region.
The longer time from VREF crossing until the ringback into the “overdrive” region required in Case B allows the
ringback to be closer to VREF for a defined period.
NOTE:
Specified for an edge rate of 0.3–0.8 V/ns. See the Pentium Pro Family Developer’s Manual for the definition of these
terms. See the figures below for the generic waveforms. All values determined by design/characterization.
NOTES:
1. Specified for an edge rate of 0.3–0.8 V/ns.
See the Pentium Pro Family Developer’s Manual for the definition of these terms.
See the figures below for the generic waveforms.
All values determined by design/characterization.
Table 11. 450KX/GX GTL+ Signal Groups Ringback Tolerance—Case A
Parameter
Min
Unit
Figure
α: Overshoot
100
mV
8, 9
τ: Minimum Time at High or Low
2.25
ns
8, 9
ρ: Amplitude of Ringback
-100
mV
8, 9
δ: Duration of Square-wave Ringback
N/A
ns
8, 9
φ: Final Settling Voltage
100
mV
8, 9