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2.1SchematicDiagram
2.2CircuitFunction
2.2.1AnalogInputs
2.2.2Power
2.2.3Outputs
Chapter2
SLWU020B–February2005–RevisedFebruary2006
CircuitDescription
TheschematicdiagramfortheEVMisattachedattheendofthisdocument.
ThefollowingparagraphsdescribethefunctionofEVMcircuits.Seetherelevantdatasheetforthedevice
operatingcharacteristics.
TheEVMcanbeconfiguredtoprovidetheADCwitheithertransformer-coupledordifferentialamplifier
inputsfromasingle-endedsource.Thedefaultconfigurationusesthetransformerconfigurationforwhich
thelayouthasbeenoptimizedtogivethebestperformance.TheinputsareprovidedviaSMAconnectors
J11fortransformercoupledinputandJ10fordifferentialamplifierinput.Tosetupforoneoftheseoptions,
theEVMmustbeconfiguredasfollows:
1.Fora1:1transformercoupledinputtotheADC,asingleendedsourceisconnectedtoJ11.SJP3has
pins1and2shortedandSJP4haspins2and3shorted.ThisisthedefaultconfigurationfortheEVM.
2.Foradifferentialinputintotheamplifier,theinputsourceisconnectedtoJ10.SJP3haspins2and3
shortedandSJP4haspins1and2shorted.±5VDCmustbeconnectedtotheboardtoprovidepower
toU3andU4forthisconfiguration.
PowerissuppliedtotheEVMviabananajacksockets.Aseparateconnectionisprovidedfora+3.3V
digitalbuffersupply(J1andJ2),5-Vanalogsupply(J3andJ2),±5-Vamplifiersupply(J7,J8,andJ12),
and3.3-Vexternalbuffersupply(J4andJ6).Asingle3.3-VbuffersupplycouldbeusedbyinstallingL6.
Inthiscase,connectthe3.3VtoJ1andthereturntoJ2.
ThedataoutputsfromtheADCarebufferedusingaTexasInstrumentsSN74AVC16244.Outputdata
headerJ9isastandard40-pinheaderona100-milgrid,andallowseasyconnectiontoalogicanalyzer.
TheconnectorpinoutislistedinTable2-1.Furthermore,twotestpointsareprovidedandcanbe
monitoredusingamultimeter.DescriptionofthetestpointsislistedinTable2-2.
SLWU020B–February2005–RevisedFebruary2006CircuitDescription7
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