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ADS8509
SLAS324A–OCTOBER2004–REVISEDJUNE2005
TerminalFunctions
终端
描述
namedbno.dwno.i/o
agnd122–analogground.usedinternallyasgroundreferencepoint.minimalcurrentflow.
AGND297–Analogground
busy2517obusyoutput.fallswhenaconversionisstarted,andremainslowuntiltheconversioniscompleted
andthedataislatchedintotheoutputshiftregister.
cap65–referencebuffercapacitor.2.2-µftantalumtoground.
cs2416–chipselect.internallyoredwithr/c.
data1713oserialdataoutput.dataissynchronizedtodataclk,withtheformatdeterminedbythelevelof
sb/btc.intheexternalclockmode,after16bitsofdata,theads8509outputsthelevelinputon
tagaslongascsislowandr/cishigh(看Figure8和Figure9).ifext/intislow,datais
validonboththerisingandfallingedgesofdataclk,andbetweenconversionsdatastaysat
thelevelofthetaginputwhentheconversionwasstarted.
dataclk1612i/oeitheraninputoranoutputdependingontheext/intlevel.outputdataissynchronizedtothis
时钟.ifext/intislow,dataclktransmits16pulsesaftereachconversion,andthenremains
lowbetweenconversions.
DGND1410–Digitalground
ext/int139–selectsexternalorinternalclockfortransmittingdata.ifhigh,dataisoutputsynchronizedtothe
clockinputondataclk.iflow,aconvertcommandinitiatesthetransmissionofthedatafromthe
previousconversion,alongwith16-clockpulsesoutputondataclk.
nc5,8,10,––noconnect
11,18,
20,22,
23
pwrd2618ipowerdowninput.ifhigh,conversionsareinhibitedandpowerconsumptionissignificantly
减少.resultsfromthepreviousconversionaremaintainedintheoutputshiftregister.
r/c2115iread/convertinput.withcslow,afallingedgeonr/cputstheinternalsample-和-holdintothe
holdstateandstartsaconversion.whenext/intislow,thisalsoinitiatesthetransmissionofthe
dataresultsfromthepreviousconversion.ifext/intishigh,arisingedgeonr/cwithcslow,或者
afallingedgeoncswithr/chigh,transmitsapulseonsyncandinitiatesthetransmissionof
datafromthepreviousconversion.
ref76i/oreferenceinput/输出.outputsinternal2.5-vreference.canalsobedrivenbyexternalsystem
涉及.inbothcases,bypasstogroundwitha2.2-µftantalumcapacitor.
R1
在
11ianaloginput.看Table3forinputrangeconnections.
R2
在
33ianaloginput.看Table3forinputrangeconnections.
R3
在
44ianaloginput.看Table3forinputrangeconnections.
sb/btc128oselectstraightbinaryorbinary2'scomplementdataoutputformat.ifhigh,dataisoutputina
straightbinaryformat.iflow,dataisoutputinabinary2'scomplementformat.
sync1511osyncoutput.thispinisusedtosupplyadatasynchronizationpulsewhentheextlevelishigh
andatleastoneexternalclockpulsehasoccuredwhennotinthereadmode.seetheexternal
clockmodesdesciptions.
tag1914itaginputforuseintheexternalclockmode.ifextishigh,digitaldatainputfromtagisoutput
ondatawithadelaythatisdependentontheexternalclockmode.看Figure8和Figure9.
V
ANA
2719ianalogsupplyinput.nominally+5v.connectdirectlytopin20,anddecoupletogroundwith
0.1-µfceramicand10-µftantalumcapacitors.
V
DIG
2820idigitalsupplyinput.nominally+5v.connectdirectlytopin19.mustbe
≤
V
ANA
.
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