Fully CMOS integrated micropower battery monitor

Abstract

A CMOS micropower battery monitor circuit which operates at supply voltages down to 2 V is presented. It is a part of a more complex system, where it detects a lower than 2.2 V supply voltage and produces a shut-down signal. The circuit consists of a voltage divider, a comparator and a band-gap voltage reference. A power-down function is also included. The circuit presented has been integrated in a conventional 2-μm n-well CMOS process and evaluated experimentally. It occupies a silicon area of 0.25 mm 2 and has a total power consumption below 30 μW at V DD = 3 D.