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12-10
GTL+ INTERFACE SPECIFICATION
If either the rising or falling edge is slower than 0.3V/ns through the overdrive region beyond
V
REF
, (i.e., does not always stay ahead of an 0.3V/ns line), then the flight time for a rising edge
is determined by extrapolating back from the signal crossing of V
REF
+200 mV to V
REF
using
an 0.3V/ns slope as indicated in Figure 12-6.
If the signal is not monotonic while traversing the overdrive region (V
REF
to V
REF
+200 mV ris-
ing, or V
REF
to V
REF
- 200 mV falling), or rings back into the overdrive region after crossing
V
REF
, then flight time is determined by extrapolating back from the last crossing of V
REF
± 200
mV using a line with a slope of 0.8V/ns (the maximum allowed rising edge rate). This yields a
new V
REF
crossing point to be used for the flight time calculation. Figure 12-7 represents the
situation where the signal is non-monotonic after crossing V
REF
on the rising edge.
Figure 12-8 shows a falling edge that rings back into the overdrive region after crossing V
REF
,
and the 0.8V/ns line used to extrapolate flight time. Since strict adherence to the edge rate spec-
ification is not required for Hi-to-Lo transitions, and some drivers’ falling edges are substantially
faster than 0.8V/ns --at both the fast and slow corners--, care should be taken when using the
0.8V/ns extrapolation. The extrapolation is invalid whenever it yields a V
REF
crossing that oc-
curs earlier than when the signal’s actual edge crosses V
REF
. In that case, flight time is defined
to be the longer of: the time when the input at the receiver crosses V
REF
initially, or when the
line extrapolated (at 0.8V/ns) crosses V
REF
. Figure 12-8 illustrates the situation where the ex-
trapolated value would be used.
Figure 12-6. Flight Time of a Rising Edge Slower Than 0.3V/ns
Summary of Contents for Pentium Pro Family
Page 17: ...1 Component Introduction ...
Page 26: ...2 Pentium Pro Processor Architecture Overview ...
Page 27: ......
Page 36: ...3 Bus Overview ...
Page 62: ...4 Bus Protocol ...
Page 105: ...5 Bus Transactions and Operations ...
Page 126: ...6 Range Registers ...
Page 131: ...7 Cache Protocol ...
Page 135: ...8 Data Integrity ...
Page 148: ...9 Configuration ...
Page 161: ...10 Pentium Pro Processor Test Access Port TAP ...
Page 172: ...11 Electrical Specifications ...
Page 201: ...12 GTL Interface Specification ...
Page 229: ...13 3 3V Tolerant Signal Quality Specifications ...
Page 233: ...14 Thermal Specifications ...
Page 239: ...15 Mechanical Specifications ...
Page 241: ...15 2 MECHANICAL SPECIFICATIONS s Figure 15 1 Package Dimensions Bottom View ...
Page 252: ...16 Tools ...
Page 260: ...16 8 TOOLS Figure 16 4 Generic MP System Layout for Debug Port Connection ...
Page 264: ...17 OverDrive Processor Socket Specification ...
Page 290: ...A Signals Reference ...
Page 320: ...Index ...
Page 328: ......