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APPLICATIONINFORMATION
ApplicationOperatingConditions
SizingPullupResistor
R
PU
V
DPU
0.35 V
0.015 一个
PCA9306
dualbidirectionali2cbusandsmbusvoltage-leveltranslator
SCPS113–OCTOBER2004–REVISEDAPRIL2005
看Figure2
MINTYP
(1)
MAXUNIT
V
REF2
ReferencevoltageV
REF1
+0.62.15v
ENEnableinputvoltageV
REF1
+0.62.15v
V
REF1
referencevoltage01.54.4v
I
通过
Passswitchcurrent14mA
I
REF
涉及-transistorcurrent5µa
T
一个
operatingfree-airtemperature–4085°c
(1)alltypicalvaluesareatt
一个
=25°c.
thepullupresistorvalueneedstolimitthecurrentthroughthepasstransistor,whenitisintheonstate,toabout
15ma.thisensuresapassvoltageof260mvto350mv.ifthecurrentthroughthepasstransistorishigher
than15ma,thepassvoltagealsoishigherintheonstate.tosetthecurrentthrougheachpasstransistorat
15ma,thepullupresistorvalueiscalculatedas:
thefollowingtablesummarizesresistorvalues,referencevoltages,andcurrentsat15ma,10ma,and3ma.
theresistorvalueshowninthe+10%column(oralargervalue)shouldbeusedtoensurethatthepassvoltage
ofthetransistoris350mvorless.theexternaldrivermustbeabletosinkthetotalcurrentfromtheresistorson
bothsidesofthepca9306deviceat0.175v,althoughthe15maappliesonlytocurrentflowingthroughthe
pca9306device.
PULLUPRESISTORVALUES
(1)(2)
pullupresistorvalue(
Ω
)
15mA10mA3mA
V
DPU
NOMINAL+10%
(3)
NOMINAL+10%
(3)
NOMINAL+10%
(3)
5V31034146551215501705
3.3v1972172953259831082
2.5v143158215237717788
1.8v97106145160483532
1.5v7785115127383422
1.2v57638594283312
(1)calculatedforv
OL
=0.35v
(2)assumesoutputdriverv
OL
=0.175vatstatedcurrent
(3)+10%tocompensateforv
DD
rangeandresistortolerance
9
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