a method and device for supplementing current from the usb bus for enumerating usb devices that require additional current beyond that allowable by usb bus specification is disclosed . a chargeable power source , such as a capacitor or rechargeable battery , is supplied to the enumeration circuitry and is charged from the usb bus for an initial period of time . the charged power source is then discharged to supplement the allowable current available for enumeration during a second period of time . it is during this second period of time that the enumeration takes place . the circuitry may exist in the usb device or may be supplied separately as a power monitor or power maintenance chip or device .