Stmicroelectronics S.r.l.

Alex Pojer

Adalberto Mariani

Claudia Castelli

Fabrizio Fraternali

A charge counter for monitoring the charge of the battery state of an electronic device includes a sensing circuit of the charge and discharge current of the battery. The sensing circuit includes a differential amplifier having inputs coupled to the terminals of a sensing resistor of the battery current, a resettable integrator of the output signal of the amplifier, a first comparator and a second comparator of the output signal of the integrator generating a logic charge interrupt signal and a logic discharge interrupt signal, respectively. The sensing circuit also includes a switch for discharging the capacitance of the integrator momentarily closed by a logic circuit at every transition of the output signal of one or the other of the first and second comparators. Further, the sensing circuit includes a processor for the interrupts which monitors the state of charge of the battery, a timer for measuring the time elapsing from the start of a new integration ramp and the switching instant of either one of the first and second comparators, and a nonvolatile memory register containing the measure of the time interval of integration of the offset of the differential amplifier up to the switching of either of the first and second comparators.

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Cassinetta di Biandronno, Italy

Alex Pojer