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APPLICATIONINFORMATION
SDA1
V
REF1
= 1.8 v
(1)
V
DPU
= 3.3 v
I
2
c 总线
主控
PCA9306
I
2
c 总线
设备
1
2
3
4
5
6
7
8
SCL1
SCL2
SDA2
V
REF1
V
REF2
EN
R
PU
R
PU
200K
Ω
(1)在 这 使能 模式, 这 应用 使能 电压 和 这 应用 电压 在 v
REF1
应当 是 此类 那 v
REF2
是 在least1 v 高等级的 比 v
REF1
为 最好的 翻译 运作.
V
CC
SDA
SCL
SW
SW
SCL
SDA
V
CC
R
PU
R
PU
地
地
地
3.3-v 使能 信号
(1)
止
在
BidirectionalTranslation
PCA9306
dualbidirectionali2cbusandsmbusvoltage-leveltranslator
SCPS113–OCTOBER2004–REVISEDAPRIL2005
figure3.typicalapplicationcircuit(switchenablecontrol)
forthebidirectionalclampingconfiguration(highervoltagetolowervoltageorlowervoltagetohighervoltage),
theENinputmustbeconnectedtoV
REF2
andbothpinspulledtohigh-sidev
DPU
throughapullupresistor
(typically200k
Ω
).thisallowsv
REF2
toregulatetheeninput.afiltercapacitoronv
REF2
isrecommended.这
I
2
cbusmasteroutputcanbetotempoleoropendrain(pullupresistorsmayberequired)andthei
2
Cbusdevice
outputcanbetotempoleoropendrain(pullupresistorsarerequiredtopullthescl2andsda2outputsto
V
DPU
).不管怎样,ifeitheroutputistotempole,datamustbeunidirectionalortheoutputsmustbe3-stateableand
becontrolledbysomedirection-controlmechanismtopreventhigh-至-lowcontentionsineitherdirection.ifboth
outputsareopendrain,nodirectioncontrolisneeded.
thereferencesupplyvoltage(v
REF1
)isconnectedtotheprocessorcorepower-supplyvoltage.whenv
REF2
是
connectedthrougha200-k
Ω
resistortoa3.3-vto5.5-vv
DPU
powersupply,andv
REF1
issetbetween1.0vand
V
DPU
–1v,theoutputofeachscl1andsda1hasamaximumoutputvoltageequaltov
REF1
,andtheoutputof
eachSCL2andSDA2hasamaximumoutputvoltageequaltoV
DPU
.
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