Texas Instruments SLAU245 Network Card User Manual


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1Introduction
2EVMSchematicandLayout
User'sGuide
SLAU245–March2008
SN65HVS880EVMUser'sGuide
TheSN65HVS880evaluationmodule(EVM)supportstheparametricevaluationoftheSN65HVS880
digitalinputserializer.ItisintendedtobeusedinconjunctionwiththeSN65HVS880datasheet,
(SLAS252).
Note:thisEVMisnotintendedforelectromagneticcompatibility(EMC)tests.
Figure1showstheboardcircuitschematic,andFigure2showstheboardlayouttopview.Theboard
includesaterminalblock,TB1,andfourconnectors,JMP1to4.
TB1receivestheboardsupplyof24Vnominal.V24suppliestheSN65HVS880device,andVFIELD
providesthesupplyforsensorswitches.
UpontheapplicationofV24,theblueChip-OkayLED(CHOK)indicatesproperboardfunction.Atthe
sametime,theredLEDindicates5Vavailabilityattheregulatoroutput5VOP.
JMP1providesthefieldinputsIN0:IN7forfieldvoltagesof24Vnominal.Theycanbeappliedvia:
a.anexternalsupplyinseriestoasensorswitchconnectedtoafieldinput,
b.orasensorswitchconnectedbetweenandinputandVFIELD,
c.oradirectconnectionbetweenaninputandVFIELD.
Inallthreecases,a24VlevelrepresentstheON-statusofasensorswitch,whichisindicatedbythe
correspondingLEDsD0:D7.
JMP2providesaccesstothecontrolanddatalinesoftheinternalserializer.Tooperatetheserializer,CE
mustbeconnectedeithertogroundortoCLK.
Uponanactive-lowloadpulse,(ahigh-to-low-to-hightransition)atLD,thestatusinformationofthefield
inputsislatchedintotheserializer.ApplyingeightconsecutiveclockcyclesatCLK,shiftsouttheserializer
dataatSOPwitheachrisingedgeoftheclock.
CascadingofmultipleboardsisalsopossiblebyconnectingtheSOPoutputofaleadingdevicewiththe
SIPinputofafollowingdevice.
JMP3allowstheselectionofthreedifferentdebouncetimesand3differentcurrentlimits.
Debouncedefaultis3ms,anddoesnotrequireanyconnectionbetweentheDBinputstoground.
Otherwise,forzerodebouncetimeconnectDB1toground,andfor1msdebouncetimeconnectDB0to
ground.
Note:theopenDBinputsareinternallypulledhighandwillnotfloat.
SettingaspecificcurrentlimitrequiresaconnectionbetweentheR
LIM
outputandoneoftheresistors,R
LIM
1:3.Foracurrentlimitof3.6mAconnectR
LIM
to24.9kΩ,for3mAto30.1kΩ,andfor2.5mAto36.1kΩ.
JMP4allowstoconnectVFIELDtoV24,thusdrivingtheboardwithonlyonesupply.
Fordetailedinformationondevicefunctionalityandsystemdesignrecommendations,seethe
SN65HVS880datasheet.
SLAU245–March2008SN65HVS880EVMUser'sGuide1
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