Microcontroller Controls Current-Loop AFE Protection

Abstract:Thefragilecurrent-shuntresistorintheanalogfrontendofanisolated0–20mAprecisioncurrentloopcanbeprotectedbyafastfuseoranautomaticcurrent-limitingswitch.Thecircuitshown,however,isfasterthanafuse,requiresnoreplacement,and(unliketheswitch)providesmicroprocessorcontrolwithanoptiontologthefaultevents.Thecircuitincludesacomparator(MAX9910),amicroprocessorsupervisorwithwatchdogtimer(MAX6706),aD-typeflip-flop,anNORgate,anORgate,andasolid-staterelay.Maxim>Designsupport>Appnotes>AmplifierandComparatorCircuits>APP4850Maxim>Designsupport>Appnotes>MicroprocessorSupervisorCircuits>APP4850Maxim>Designsupport>Appnotes>ProtectionandIsolation>APP4850Keywords:0-20mAcurrentloop,analogfrontend,AFE,current-shuntresistor,shuntprotectionFeb15,2011APPLICATIONNOTE4850MicrocontrollerControlsCurrent-LoopAFEProtectionBy:AnatolyAndrusevichAbstract:Thefragilecurrent-shuntresistorintheanalogfrontendofanisolated0