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Digital Circuit Interface for Optical Switch
Indmostdofdapplicationdcases,dOpticaldSwitchdactsdasdadsensordordswitchdindthedsystem;dTodbedadInputdfordASICdordMicrod
Processordindandelectricaldequipmentdwithdintelligentdfunction.dFollowingdfguredprovidedadtypicaldcircuitsdfordOpticald
SwitchdtodinterfacedwithdthedASICdanddMicrodProcessord.d(Pleasedreferdthedproductddatadfordspecifcationsdondthedindi-
vidualdpartdnumberdfordthedIc(on)dlightdcurrentdvalue.)
Fig.d1dCMOSdseriesdinterfacedcircuit
ExampledcalculationdfordFig.d1d:
HeredchoicedLTH-301-19dfordandexample.dIndmostdofdactualdcasedthedoutsideddimensionsdisdfrstdparameterdtodbedcon-
sidereddtodftdthedapplicationdrequirementdanddthedseconddisdIc(on)dlightdcurrentdvalue.dHeredbreakddowndthedcalcula-
tiondintodfewdstepsdtoddemonstratedthedwaydtodchoicedsuitabledR1danddR2dvaluedfordthedOpticaldswitchdwithdspecifcedd
Ic(on)dvalue.
AccordingdthedspecifcationsdofdLTH-301-19.
ThedIc(on)dmindisd1.5mAdatdIFd=d20mA,dVced=d5V
IFd=d(dVccd-dVFd)d/dR1
dddd=d(d5Vd-d1.2Vd)d/dR1d..............................d(dVFdisdclosedtod1.2VdatdIFdfromd10mAdtod20mA)
SuggestdIFd=d10mAdthendR1d=d(d5Vd-d1.2V)d/d10mA,dR1d=d380dOhms
Fig.d2ddForwarddI-VdcharacteristicsdofdthedIRdLED
PTIR > Application Note
209 d2013dCatalogd|dwww.liteon.com/opto
