12-9
GTL+ INTERFACE SPECIFICATION
The time difference between when a signal at the input pin of a receiving
agent (adjusted to meet the receiver manufacturer’s conditions required for
AC specifications) crosses V
REF
, and the time that the output pin of the
driving agent crosses V
REF
were it driving the test load used by the
manufacturer to specify that driver’s AC timings.
An example of the simplest Flight Time measurement is shown in Figure 12-5. The receiver
specification assumes that the signal maintains an edge rate greater than or equal to 0.3V/ns at
the receiver chip pad in the overdrive region from V
REF
to V
REF
+200 mV for a rising edge and
that there are no signal quality violations after the input crosses V
REF
at the pad. The Flight Time
measurement is similar for a simple Hi-to-Lo transition. Notice that timing is measured at the
driver and receiver pins while signal integrity is observed at the receiver chip pad. When signal
integrity at the pad violates the guidelines of this specification, and adjustments need to be made
to flight time, the adjusted flight time obtained at the chip pad can be assumed to have been ob-
tained at the package pin, usually with a small timing error penalty.
The 0.3V/ns edge rate will be addressed later in this document, since it is related to the condi-
tions used to specify a GTL+ receiver’s minimum setup time. What is meant by edge rate is nei-
ther instantaneous, nor strictly average. Rather, it can best be described for a rising edge -- by
imagining an 0.3V/ns line crossing V
REF
at the same moment that the signal crosses it, and ex-
tending to V
REF
+200 mV, with the signal staying ahead (earlier in time) of that line at all times,
until it reaches V
REF
+200 mV. Such a requirement would always yield signals with an average
edge rate >0.3V/ns, but which could have instantaneous slopes that are lower or higher than
0.3V/ns, as long as they do not cause a crossing of the inclined line.
Figure 12-5. Measuring Nominal Flight Time
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: ......