www.德州仪器.com
switchingcharacteristics,5-vnominalsupply
tb5d1m,tb5d2h
SLLS579B–SEPTEMBER2003–REVISEDMAY2004
THIRDSTATE—
atb5d1m(ortb5d2h)driverproducespseudo-ecllevels,andhasathird-statemode,这个
isdifferentthanaconventionalttldevice.whenatb5d1m(ortb5d2h)driverisplacedinthethirdstate,这
baseoftheoutputtransistorsispulledlow,bringingtheoutputsbelowtheactive-lowlevelofstandardpecl
设备.[forexample:thetb5d1mlowoutputlevelistypically2.7v,whilethethirdstateoutputlevelisless
than0.1v.]inabidirectional,multipoint,busapplication,thedriverofonedevice,whichisinitsthirdstate,将
bebackdrivenbyanotherdriveronthebuswhosevoltageinthelowstateislowerthanthethird-stateddevice.
thiscouldcomeaboutduetodifferencesinthedriver'sindependentpowersupplies.inthiscase,thedevicein
thethirdstatecontrolstheline,thusclampingthelineandreducingthesignalswing.ifthedifferencevoltage
betweentheindependentdriverpowersuppliesissmall,thisconsiderationcanbeignored.againusingthe
tb5d1mdriverasanexample,atypicalsupplyvoltagedifferencebetweenseparatedriversof>2vcanexist
withoutsignificantlyaffectingtheamplitudeofthesignal.
overrecommendedoperatingconditionsunlessotherwisenoted
parametertestconditionsmintyp
(1)
maxunit
t
P1
propagationdelaytime,inputhightooutput
(2)
1.22
C
L
=5pf,seefigure1and
ns
Figure3
t
P2
propagationdelaytime,inputlowtooutput
(2)
1.22
∆
t
P
capacitivedelay0.010.03ns/pf
propagationdelaytime,
t
PHZ
712
高-水平的-至-高-impedanceoutput
propagationdelaytime,
t
PLZ
712
低-水平的-至-高-impedanceoutput
C
L
=5pf,seefigure2and
ns
Figure3
propagationdelaytime,
t
PZH
512
高-阻抗-至-高-leveloutput
propagationdelaytime,
t
PZL
412
高-阻抗-至-低-leveloutput
t
skew1
outputskew,|t
P1
-t
P2
|0.150.3
t
shew2
outputskew,|t
PHH
-t
PHL
|,|t
PLH
-t
PLL
|0.151.1
C
L
=5pf,seefigure1and
ns
Figure3
t
skew(pp)
部分-至-partskew
(3)
0.11
∆
t
skew
outputskew,differencebetweendrivers
(4)
0.3
t
TLH
risetime(20%-80%)0.72
C
L
=5pf,seefigure1and
ns
Figure3
t
THL
falltime(80%-20%)0.72
(1)alltypicalvaluesareat25
°
candwitha5-vsupply.
(2)parameterst
P1
andt
P2
aremeasuredfromthe1.5vpointoftheinputtothecrossoverpointoftheoutputs(seefigure1).
(3)t
skew(pp)
isthemagnitudeofthedifferenceindifferentialpropagationdelaytimes,t
P1
ort
P2
,betweenanyspecifiedoutputsoftwodevices
whenbothdevicesoperatewiththesamesupplyvoltage,atthesametemperature,andhaveidenticalpackagesandtestcircuits.
(4)
∆
t
skew
isthemagnitudeofthedifferenceindifferentialskewt
skew1
betweenanyspecifiedoutputsofasingledevice.
4
: 点此下载
