Bus-powered device

摘要

A bus powered device includes a signal processing control circuit connected to and powered by a bus at a predetermined operating current and a bus current modulator circuit interconnected in series with a signal processing control circuit to the bus for providing a bipolar communication signal having an average current of substantially zero; the total series current of both the circuits is only the current required by the signal processing control circuit or the absolute value of the most negative current excursion during communication, whichever is greater.