4 -20mA回路供电故障保护

摘要：该电路提供了一个4-20mA电流环路灵活的故障保护。此外，它包括为恢复环路上施加的数字信号（如HART协议）的电路。

Maxim/Dallas>AppNotes>CIRCUITPROTECTIONINTERFACECIRCUITSKeywords:4-20mAcurrentloop,faultprotection,currentlimiting,current-senseamplifiersApr22,2004APPLICATIONNOTE3195AddFaultProtectionto4-20mALoopSupplyThiscircuitprovidesflexiblefaultprotectionfora4-20mAcurrentloop.Inaddition,itincludescircuitryforrecoveringdigitalsignals(suchastheHARTprotocol)imposedontheloop.4-20mAcurrentloopsconsistofapowersourceandcurrent-measuringdeviceatthecontrolend,andafieldtransmitterthatsensesprocess-variableinformation(liketemperatureorpressure)andconvertsittoacurrent(Figure1).Most4-20mAindustrialloopsarepoweredby24VDC,butthatvoltagecanrangefrom12Vto36V.Theloopvoltageino