Dynamic Siphon Steals Current from USB Port

Abstract:ThiscircuitexploitsallthepoweravailablefromaUSBportbydynamicallyadjustingtheamountofcurrentdeliveredtotheload,therebysiphoningarelativelyconstant(andmaximum)currentfromtheUSBport.Includedareacurrent-senseamplifier(MAX4173),voltagereference(MAX6129),andprecisionopamp(MAX4238).Maxim>AppNotes>AmplifierandComparatorCircuitsInterfaceCircuitsVoltageReferencesKeywords:USBports,USB-portpower,current-senseamplifiers,voltagereferences,opamps,n-channelMOSFETsJan05,2011APPLICATIONNOTE4563DynamicSiphonStealsCurrentfromUSBPortAbstract:ThiscircuitexploitsallthepoweravailablefromaUSBportbydynamicallyadjustingtheamountofcurrentdeliveredtotheload,therebysiphoningarelativelyconstant(andmaximum)currentfromtheUSBport.Includedareacurrent-senseamplifier(MAX4173),voltagereference(MAX6129),andprecisionopamp(MAX4238).AsimilarversionofthisarticleappearedintheDecmeber15,2006issueofEDNmagazine.USBportscanbeahandysourceof5Vpower.NotonlycanaUSBportpowera