UPD72012 datasheet(29/36 Pages) NEC

29 / 36 page

Data Sheet S13918EJ3V0DS

µPD72012

(4) HUB differential delay, differential jitter, and SOP distortion

50% point of

initial swing

VSS

Downstream

port of HUB

Upstream

end of cable

VSS

(b) Downstream HUB delay excluding cable

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

(a) Downstream HUB delay including cable

Downstream

end of HUB

HUB delay

downstream

tHDD1

Crossover point

50% point of

initial swing

HUB delay

downstream

tHDD2

Upstream

port of HUB

Crossover point

VSS

Downstream

port of HUB

VSS

Upstream port or

end of cable

HUB delay

upstream

tHDD1, tHDD2

Crossover point

VSS

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