bq2945 Gas Guage IC

Benchmarq Microelectronics, Inc. announces the bq2945 Gas Gauge IC for capacity monitoring of rechargeable battery packs. The bq2945 represents the latest addition to Benchmarq's growing portfolio of capacity monitoring ICs. The bq2945 supports version 1.0 of the System Management Bus (SMBus) and version 1.0 of the Smart Battery Data (SBD) specifications and can interface with the host system and battery charger to form a comprehensive battery management system that is chemistry independent.

Designed for battery pack integration, the bq2945 supports the complete Smart Battery Data set, which includes the reporting of critical battery parameters such as remaining battery capacity, battery voltage, and pack temperature. The bq2945 communicates the battery parameters to the host system using the two-wire System Management Bus. The monitor IC also broadcasts warning messages, battery charging requirements, and battery full charge indication to the host or charge controller. For added flexibility, the bq2945 adds two programmable input/output ports that can be used to monitor the safety circuit in Li-Ion battery packs. Direct connections for five LEDs and a switch allow remaining capacity indication in 20% increments at the touch of a button.

The bq2945 is packaged in a small 16-pin 150-mil SOIC and--together with the necessary external components--can occupy less than 3/4 square inch of PCB space. The small PCB space required eases the restrictions on pack integration. The complete solution is small enough to fit in the crevice between two standard 17650 or 18650 cylindrical cells.

The bq2945 is designed for battery packs in applications such as:
Notebook computers
Handheld terminals and PDAs
Wireless communication devices
Portable medical and test equipment

"The bq2945 is unique. It not only allows manufacturers to make portable systems fully SBS-compliant, but also provides the design flexibility to meet the system's space requirements and match the cells' characteristics," said Peter Fundaro, Product Marketing Manager. "As an added benefit, the two programmable ports give the battery manufacturer or battery VAR the ability to monitor the safety circuit in a Li-Ion battery pack at no additional cost."

A lot of money and time have been spent by the semiconductor manufacturers in evolving the gas-guage concept put into effect here. Those of us who have laptops know the absurdity of the warnings that you get today: the Toshiba this is being written on will alarm at 20% and then 10% of battery capacity. The difference between 20 and 10 is about 15 minutes. Between 10 and really dying is about 40 minutes; go figure!

The bq2945 is a major jump in the potentials available for battery monitoring in these circumstances for what seems to be all types of current battery systems.

Samples and development kits for the bq2945 are available now. Production quantities will be available in December with the 16-pin 50-mil SOIC at less than $4.50 in OEM quantities. The development kit is priced at $199.