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

摘要

A circuit comprises a battery field-effect transistor (FET) coupled between a battery and an electronic system 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 provides a plurality of switch control signals based on a system state input. A switching circuit 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 provides a voltage indicative of the current flowing through the replica FET.

主权项

1. A circuit comprising:
a field-effect transistor (FET) having a first terminal configured to be coupled to a battery and a second terminal configured to be coupled to an electronic system, wherein current from the battery flows through the FET to the electronic system, and wherein the FET comprises a plurality of parallel FET segments having separate control terminals; a logic block having an input to receive a system state input and having an output to provide a plurality of switch control signals based on the system state input; a switching circuit having first terminals coupled to the plurality of switch control signals and having second terminals independently coupled to the separate control terminals of the plurality of FET segments to selectively couple the separate control terminals of the plurality of 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; and an analog to digital converter having a first input terminal coupled to the first terminal of the FET, having a second input terminal coupled to the second terminal of the FET and having an output to provide a digital value in response to signals applied to the first input terminal and the second input terminal.