TheAD7991/AD7995/AD7999are12-/10-/8-bit,lowpower,successiveapproximationADCswithanI2C®-compatibleinterface.Eachpartoperatesfromasingle2.7Vto5.5Vpowersupplyandfeaturesa1μsconversiontime.Thetrack-and-holdamplifierallowseachparttohandleinputfrequenciesofupto14MHz,andamultiplexerallowstakingsamplesfromfourchannels.
EachAD7991/AD7995/AD7999providesa2-wireserialinterfacecompatiblewithI2Cinterfaces.TheAD7991andAD7995comeintwoversionsandeachversionhasanindividualI2Caddress.ThisallowstwoofthesamedevicestobeconnectedtothesameI2Cbus.Bothversionssupportstandard,fast,andhighspeedI2Cinterfacemodes.TheAD7999comesinoneversion.
TheAD7991/AD7995/AD7999normallyremaininashutdownstate,poweringuponlyforconversions.Theconversionprocessiscontrolledbyacommandmode,duringwhicheachI2CreadoperationinitiatesaconversionandreturnstheresultovertheI2Cbus.
Whenfourchannelsareusedasanaloginputs,thereferenceforthepartistakenfromVDD;thisallowsthewidestdynamicinputrangetotheADC.Therefore,theanaloginputrangetotheADCis0VtoVDD.Anexternalreference,appliedthroughtheVIN3/VREFinput,canalsobeusedwiththispart.