BATTERY FUEL GAUGES USING FET SEGMENT CONTROL TO INCREASE LOW CURRENT MEASUREMENT ACCURACY

摘要

A circuit comprises a battery field effect transistor (FET 512) coupled between a battery (502) and an electronic system (518) so that current from the battery flows through the battery FET to the electronic system. A replica FET couples the battery to a current sensing circuit. One of the battery FET and the replica FET comprises a plurality of parallel FET segments having separate control terminals. A logic block (520) provides a plurality of switch control signals (544) based on a system state input. A switching circuit (510) receives the switch control signals and selectively couples the separate control terminals of the FET segments to one of a first reference voltage terminal or a second reference voltage terminal to independently turn each FET segment on or off. The current sensing circuit (506) provides a voltage indicative of the current flowing through the replica FET.