The bq2016 gas gauge IC for battery pack or in-system installation maintains an accurate record of available battery capacity. To integrate charge and discharge activity of the battery, the IC monitors a voltage drop across a sense resistor connected in series with the cells of the battery. The bq2016 compensates for battery temperature, charge/discharge rate, and battery self-discharge to the charge counter to provide available-capacity information across a wide range of operating conditions. The bq2016 works with NiCd or NiMH battery packs that have a capacity of 1 to 4.5 Ah and that are designed for high discharge rate applications such as power tools.

The VPFC input sets the initial full charge reference of the battery pack. The bq2016 learns the true discharge capacity of the battery pack and automatically updates the full-charge reference during the course of a discharge cycle from full to empty. The remaining capacity is reported as the ratio between the actual discharge capacity and the full-charge capacity. The bq2016 communicates available capacity using 5 LEDs or the 1-wire communications port.

The 1-wire serial communication port (5Kb/s) allows an external processor to read and write the internal registers of the bq2016. Communication with the bq2016 is useful for pack testing or host processing of the available battery information. The internal registers include available battery capacity, voltage, temperature, current, and battery status. The RBI input maintains the register set in the event of pack voltage collapse due to a high discharge pulse.

The bq2016 circuit can operate from the cells in the pack. The REG output and an external FET provide a simple, inexpensive voltage regulator to supply power to the circuit from the cells.