标签: 纳瓦技术

PICmicro®单片机电源管理，具有纳瓦技术的PIC16F系列PICmicroMCUPowerManagedPIC16FFamilyFeaturingnanoWattTechnologyThePowerManagedPIC16F818/819andPIC16F87/88MCUfamilymergestheFLASH-basedPIC16Farchitecturethatiseasy-to-program,withonly35singlewordinstructions,withnewlowpowerfeaturesthatareidealforbatterymanagementapplications.Newpowermanagedfeaturescanincludenewoscillatorsources,anewlowcurrentWatchdogTimer,Two-SpeedStart-up,Fail-SafeClockMonitoranduptothreenewPowerManagedmodes.Thesedevicesprovidelowcostsolutionsforintelligentsmallsystemsthatrequireextendedbatterylifeandenergyefficientoperation.ThisPICmicroMCUfamilyfeaturesdataEEPROM,Self-programming,a10-bitADCwithupto7analoginputchannels,one16-bitTimerandtwo8-bitTimers,andICDcap……

Reducingpowerconsumptionisalwaysdesirableinsystemswhereresourcesmaybelimited.ThisisparticularlytrueinUSBsystems,wheredesignersmustnotonlyunderstandtherulesimposedbytheUSBspecification,butknowwhenandhowtousewhichoftheavailablepower-savingfeatures.ThisapplicationnotediscusseswaystomanagepoweronthemembersofthePIC18familyofmicrocontrollerswithnanoWatttechnologyinUSBapplications.Inthisdocument,wewillpresentasummaryoftheUSBspecificationinregardstopowermanagementanddis-tributionandtodescribewhenandhowtousepower-savingfeaturesinresponsetodifferentUSBevents.Wewillalsodiscusshowtheadvancedpower-savingfeaturesofenhancedPIC18deviceswithnanoWatttechnologycanbeusedtomeetthesegoals.OurfocusinthisdocumentisonPIC18deviceswiththeUSBperipheralandusesthePIC18F2455/2550/4455/4550familyofmicro-controllersasanexample.Allreferencestothedevicedatasheetinthisdocumentrefertothedatasheetforthisfamily(DS39632).AN950PowerManagementforPIC18USBMicrocontrollerswithnanoWattTechnologyAuthor:RawinRojvanitThisdiscussionislimitedtoUSBdevicesonlyandisnotintendedforaUSBhost.TheauthorassumesthattheMicrochipTechnologyInc.readershavesomebasicknowledgeabouttheUSBstandard.AllreferencestotheUSBspecificationinthisINTRODUCTIONdocumentreferto“USBSpecification……