New Impedance Tracking Chipset for Notebook Battery

On mid December, 2006, Texas Instruments introduced bq20z90 Impedance Track “gas gauge” chipset along with several new battery ICs. TI Impedance Track gas gauge technology was introduced to public in 2004. In that time bq20z80 was used as chipset. The release of these product is intended to improve performance and protect multi-cell lithium battery pack, especially used in notebook.

The bq20z90 is designed to work with TI product, Analog Front End (AFE) protection IC. The gas gauge in this chipset monitors battery capacity, impedance, cell balance, pen loop voltage, and other parameters, then teport to host processor via serial bus.

Impedance Track gas gauge technology able precisely measures the changes in impedance and  resistance of battery caused by aging and temperature. This capability open way to eliminates the need for a full-charge and discharge cycle.

bq20z90 has LED driver to display remaining capacity of battery. Designs that do not require display can use  bq20z70. bq20z70 is gas gauge chipset too, but without the LED driver.

The bq20z90 is designed to work with bq29330 AFE protection IC, with  I2C as communication interface between them. This cooperation allow the bq20z90 to monitor battery conditions and report the information to the host system.

bq29330’s safety parameters such as current protection thresholds and delays can be set by flexibly by program. It also provides protection for overload short-circuit in charge/discharge  conditions, and also cell over/under voltage protection.

The bq20z90 integrates SHA-1 based authentication functionality, which easily identifies potentially unsafe batteries not approved by original equipment manufacturers. A manufacturer can program the system to take action to protect the consumer if the battery pack response is not correct.

TI also offers new bqMTester smart battery development board. bqMTester eliminates the need for an onboard computer and expensive calibration/traceable power supplies and electronic loads. It calibrates and programs electronic smart battery modules based on advanced battery fuel gauges, such as the bq20z90, bq20z80 and bq20z70 devices with Impedance Track. In addition, bqMTester makes tracking battery modules in production easier by programming serial number, date, pack lot code and other defaults.

Pricing (1K):

• $3.30 for the bq20z90,
• $2.90 for the bq20z70,
• $1.45 for the bq29330,
• $1.30 for the bq26100.

Source: Texas Instruments