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ADS8504
+5V
+
+
+
+
转变 脉冲波
40 ns 最小值
200
Ω
2.2
µ
F
0.1
µ
F 10
µ
F
33.2 k
Ω
D11 (msb)
D10
D9
D8
D7
D6
D5
D4
dz 低
dz 低
dz 低
dz 低
d0 (lsb)
D1
D2
D3
2.2
µ
F
BUSY
r/c
READINGDATA
ADS8504
SLAS434–JUNE2005
basicoperation(持续)
csandr/careinternallyoredandleveltriggered.thereisnotarequirementwhichinputgoeslowfirstwhen
initiatingaconversion.如果,不管怎样,itiscriticalthatcsorr/cinitiatesconversion
n
,besurethelesscriticalinput
islowatleast10nspriortotheinitiatinginput.
toreducethenumberofcontrolpins,cscanbetiedlowusingr/ctocontrolthereadandconvertmodes.这
paralleloutputbecomesactivewheneverr/cgoeshigh.refertothereadingdatasection.
table1.controllinefunctionsforreadandconvert
csr/cbusyoperation
1xxnone.databusisinhi-zstate.
↓
01Initiatesconversion
n
.databusremainsinhi-zstate.
0
↓
1Initiatesconversion
n
.databusentershi-zstate.
01
↑
转换
n
完成.validdatafromconversion
n
onthedatabus.
↓
11Enablesdatabuswithvaliddatafromconversion
n
.
↓
10Enablesdatabuswithvaliddatafromconversion
n-1
(1)
.转换
n
inprogress.
0
↑
0Enablesdatabuswithvaliddatafromconversion
n-1
(1)
.转换
n
inprogress.
00
↑
newconversioninitiatedwithoutacquisitionofanewsignal.dataisinvalid.csand/orr/c
mustbehighwhenbusygoeshigh.
xx0newconvertcommandsignored.转换
n
inprogress.
(1)看Figure19和Figure20forconstraintsondatavalidfromconversion
n-1
.
figure17.basicoperation
theads8504outputsfullorbyte-readingparalleldatainbinary2'scomplementdataoutputformat.theparallel
outputisactivewhenr/c(pin24)ishighandcs(pin25)islow.anyothercombinationofcsandr/c3-states
theparalleloutput.validconversiondatacanbereadinafullparallel,12-bitwordortwo8-bitbytesonpins6-13
andpins15-22.字节(pin23)canbetoggledtoreadbothbyteswithinoneconversioncycle.refertoTable2
foridealoutputcodesandFigure18forbitlocationsrelativetothestateofbyte.
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