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Figure 5-10. Overdrive Region and V
5.4.4
Flight Time Definition and Measurement
Timing measurements consist of minimum and maximum flight times to take into account that
devices can turn on or off anywhere in a V
V
-∆V
REF
time the driver crosses V
crosses V
point where the signal first crosses V
monotonicity criteria are met. Similarly, minimum flight time measurements for a falling edge are
taken at the V
Figure 5-11. Rising Edge Flight Time Measurement
V
V
V
5.5
Conclusion
AGTL+ routing requires a significant amount of effort. Planning ahead and leaving the necessary
time available for correctly designing a board layout will provide the designer with the best chance
of avoiding the more difficult task of debugging inconsistent failures caused by poor signal
integrity. Intel recommends planning a layout schedule that allows time for each of the tasks
outlined in this document.
®
Intel
810A3 Chipset Design Guide
REF
V
+ 200 mV
REF
V
+ 100 mV
REF
V
∆
V
REF
REF
V
- 100 mV
REF
V
- 200 mV
REF
and V
+∆V
The minimum flight time for a rising edge is measured from the
REF
REF
REF.
when terminated to a test load, to the time when the signal first
REF
-∆V
at the receiver (see
REF
REF
+∆V
crossing and maximum flight time is taken at the V
REF
REF
Receiver Pin
Driver Pin into
Test Load
+ 200 mV
REF
+ 100 mV
REF
V
∆ V
REF
REF
- 100 mV
REF
Guardband
∆
V
V
Guardband
REF
REF
Guardband region. This region is bounded by
REF
Figure
5-11). Maximum flight time is measured to the
+∆V
, assuming that ringback, edge rate, and
REF
REF
∆ V
REF
V
Guardband
REF
Tflight-max
Tflight-min
Advanced System Bus Design
Overdrive Region (200 mV)
Overdrive Region (200 mV)
-∆V
REF
REF
Overdrive Region
crossing.
5-19
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