TI increases accuracy for Li-ion battery fuel gauging

July 02, 2013 // By Paul Buckley
Texas Instruments is claiming the industry’s smallest and most accurate Li-Ion battery fuel gauge integrated circuit, the bq27421, which boosts battery run-time in portable medical devices.

The device is suitable for wearable health monitors, inventory scanners and portable emergency lights and other consumer electronics.
Employing TI’s Impedance Track advanced battery monitoring technology typically used in tablets and smartphones, the bq27421 system-side fuel gauge in a 9-ball chipscale (WCSP) package accurately reports remaining battery capacity, state-of-charge and battery voltage, allowing portable devices to extend run-time by 50% or higher.

Designers can use the pre-configured ‘plug-and-play’ bq27421 fuel gauge with TI’s new Gauge Studio software tool to simplify battery gauging design. The file size of the Gauge Studio design tool is about ten times smaller than TI’s previous software, minimising configuration and system firmware development. The bq27421EVM-G1A evaluation development kit is available for $49.
The integrated sense resistor and 1.5 x 1.5 x 0.5-mm WCSP package result in the smallest possible total solution size compared to competing gauges. The single-cell battery fuel gauge supports embedded or removable Li-Ion batteries.

The simple-to-design ‘plug-and-play’ gauge requires minimal user configuration and system microcontroller firmware development.
The impedance track technology provides battery capacity measurement with claimed 99% accuracy, and automatically adjusts for battery ageing, self-discharge, temperature and rate changes. The bq27421costs $1.20 (1,000).
TI,  www.ti.com/bq27421-pr