The bq2052 Lithium Primary Gas 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 with the cells to determine discharge activity of the battery. The bq2052 applies compensations for battery temperature and discharge rate to the available charge counter to provide available capacity information across a wide range of operating conditions. Compensated available capacity may be directly indicated using an LED display. The LED display is programmable and can be configured as two, four, or five segments. These segments are used to depict available battery capacity. The bq2052 supports a single-wire serial communications link to an external microcontroller. The link allows the microcontroller to read and write the internal registers of the bq2052. The internal registers include available battery capacity, voltage, temperature, current, and battery status. The controller may also overwrite some of the bq2052 gas gauge data registers. The bq2052 can operate from the batteries in the pack. The REF output and an external FET provide a simple, inexpensive voltage regulator to supply power to the circuit from the cells.