Signal-To-Strobe Flight Time Relationships; Signal Length Solution Space With Furthest Apart Strobes; Signal Length Solution Space With Matched Strobes - Intel EP80579 Manual

High-Speed Design Concerns—Intel
5.6.1

Signal-to-Strobe Flight Time Relationships

High-speed interfaces are commonly latched off a strobe or a clock. Length tuning
ensures that the required setup and hold times of the data signal to the strobe signal or
clock signal are not violated due to motherboard routing effects. As a result, each data
signal is length tuned with respect to the strobe signal or clock signal. This means that
the data signals are all within tolerance of the strobe signal:
Figure 26. Signal Length Solution Space with One Strobe
Some groups of high-speed signals need to be length tuned to two strobes or clocks. In
this situation, all signals must be length matched to both strobes or clocks and the
strobes or clocks must be length matched to each other as well.
Figure 27. Signal Length Solution with Two Strobes
®
Intel EP80579 Integrated Processor Product Line
Order Number: 320068-005US
®
EP80579 Integrated Processor Product Line
Minimum_Signal
Flight Time
Maximum_Signal
Flight Time
Minimum_
Signal
Strobe
F li ght Ti me
Strobe
– to ler ance
Minimum_Signal
Flight Time
Maximum_Signal
Flight Time
Minimum_
Signal
F li ght Ti me
Shorter_Strobe
Fl i ght Ti me
Longer_Strobe
Fl ight Tim e
Longer_
Strobe
Fli ght Ti m e
– Tolerance
= Strobe – Tolerance
Flight Time
= Strobe + Tolerance
flight Time
Maximum_
Signal
Fl ight Tim e Fl igh t Tim e
tol eranc e tol era nce
F l i gh t T i m e Str obe
+ tol erance
= Longer_Strobe
Flight Time
= Shorter_Strobe
Flight Time
Maximum_
Signal Length
Signal
Solution Space
tolerance
tolerance
Shorter_
Strobe
+ Tolerance
Flight Time
– Tolerance
+ Tolerance
F li ght Ti me
Fli ght Ti m e
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