TI Power Management Fuel Gauge Predicts Battery Life In Smart Phones & Handhelds
Texas Instruments Inc. (TI) introduced its system-side fuel gauge integrated circuit (IC) with Impedance Track™ technology for smart phones and other handhelds. The 2.5 mm x 4 mm gauge is said to predict battery life with 99% accuracy to extend run-time, protect data and provide a better user experience for mobile handheld users.
The bq27500 system-side battery fuel gauge with TI’s patented Impedance Track technology is said to accurately measure data from a device’s single-cell Li-Ion battery to predict remaining battery capacity under all conditions, even as a battery ages. The tiny IC analyzes precise state-of-charge by correlating between a battery’s voltage and cell impedance, or resistance, and its current integration to adjust remaining state-of-charge up or down the predicted discharge curve.
According to the company, most handhelds today do not accurately gauge remaining battery capacity, but simply measure the cell voltage to guess the capacity. Traditional gauging techniques used in some handhelds require static and unreliable modeling methods that attempt to compensate for discharge rate, temperature and age of the cell, and must also model self-discharge and other non-measurable currents. Since these models have an inherent error, which is difficult to minimize, an end-user will not accurately know how much run-time remains as the battery ages.
The bq27500 directly measures the effect of a battery’s discharge rate, temperature, age and other factors to accurately predict remaining life within one percent error. By measuring and storing real-time battery impedance values, the IC automatically adjusts to changes in full capacity as a battery ages. State-of-charge and full capacity are calculated from the voltage and impedance measurements, eliminating the need to re-learn from a charge and discharge cycle.
As handheld systems provide more functions, the need has grown for accurate fuel gauging to intelligently manage available power, alert the user of system operating-time, and extend the run-time of the system as far as possible. Accurate battery data is used by applications processors, such as TI’s OMAP3410 processor with SmartReflex™ power and performance technologies, to optimize the system’s complete mobile power operating system. For instance, the system can leverage low-power modes, clock gating, clock throttling and dynamic voltage and frequency scaling capabilities based on battery capacity. The bq27500 provides an accurate reserve energy warning, which allows a system to save data to non-volatile memory at the end of a battery’s discharge, so work is not lost when battery life runs out.
The bq27500 is implemented on the host system’s board, and can support an embedded or removable battery. System-side implementation allows a handheld manufacturer to save cost by designing an end-equipment that does not need extra electronics added to the battery pack. As batteries continue to shrink in size, integration of electronics on the battery becomes more of a challenge. System-side implementation of the bq27500 can control and manage other main battery management functions, such as battery pack authentication.
The bq27500 is available in a 12-pin, 2.5 mm x 4 mm SON package, with a suggested retail price of $1.35 in 1,000-piece quantities.
