µPD72012
(4) HUB differential delay, differential jitter, and SOP distortion
(a) Downstream HUB delay including cable
(b) Downstream HUB delay excluding cable
Upstream
end of cable
VSS
Downstream
end of HUB
VSS
50% point of
initial swing
Upstream
port of HUB
VSS
HUB delay
downstream
tHDD1
Downstream
port of HUB
VSS
(c) Upstream HUB delay with and without cable
Crossover point
HUB delay
downstream
tHDD2
50% point of
initial swing
Downstream
port of HUB
VSS
Upstream port or
end of cable
VSS
Crossover point
HUB delay
upstream
tHDD1, tHDD2
Crossover point
HUB operation jitter:
tHDJ1 = tHDDx(J) − tHDDx(K) or tHDDx(K) − tHDDx(J) Continuous transition
tHDJ2 = tHDDx(J) − tHDDx(J) or tHDDx(K) − tHDDx(K) Pair transition
Bit after SOP width distortion (same as data jitter of next transition of SOP):
tFSOP = tHDDx(next J) − tHDDx(SOP)
The low-speed timing below is determined by the same method.
tLHDD, tLDHJ1, tLDJH2, tLUHJ1, tLUJH2, and tLSOP
Data Sheet S13918EJ3V0DS
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