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The bq2050 Lithium Ion Power Gauge™ IC is intended for battery-pack or in-system installation to maintain an accurate record of available battery capacity. The IC monitors a voltage drop across a sense resistor connected in series between the negative battery terminal and ground to determine charge and discharge activity of the battery. Compensations for battery temperature and rate of charge or discharge are applied to the charge, discharge, and self-discharge calculations to provide available capacity information across a wide range of operating conditions. Battery capacity is automatically recalibrated, or "learned," in the course of a discharge cycle from full to empty.

Nominal available capacity may be directly indicated using a five-segment LED display. These segments are used to graphically indicate available capacity. The bq2050 supports a simple single-line bidirectional serial link to an external processor (common ground). The bq2050 outputs battery information in response to external commands over the serial link.

The bq2050 may operate directly from one cell (V_BAT > 3V). With the REF output and an external transistor, a simple, inexpensive regulator can be built for systems with more than one series cell.

Internal registers include available capacity, temperature, scaled available energy, battery ID, battery status, and programming pin settings. To support subassembly testing, the outputs may also be controlled. The external processor may also overwrite some of the bq2050 power gauge data registers.