2/21/2003 - As levels of functionality in 2.5G and 3G mobile handsets and personal digital assistants (PDAs) increase, an accurate account of remaining battery power is critical, especially before an important wireless transaction. Texas Instruments (TI) (NYSE: TXN) announced the industry´s first fully integrated battery fuel gauge for single-cell lithium-ion (Li-Ion) and lithium-polymer (Li-Polymer) battery packs to calculate remaining battery capacity and system run-time. The new integrated chip significantly reduces the development time and total cost of implementing a comprehensive battery fuel gauge system in single-cell portable applications.
"As battery-powered consumer devices become more complicated and dynamic, designers of those products will require the right intelligent hardware to provide accurate information about the battery and system run-times to better manage available power," said Peter Fundaro, worldwide marketing manager for TI's battery management products. "With today's announcement, TI simplifies the design of a cost-effective accurate battery fuel gauge in single cell applications by offering a solution that performs all the necessary intelligent calculations on-chip, significantly reducing the amount of calculations performed by the host-side microcontroller."
Unlike a standard battery monitor, the bq270x0, or bqJuniorTM, battery fuel gauge incorporates an on-board processor to calculate the remaining battery capacity and system run-time (time to empty). The device measures the battery´s charge and discharge currents to within one percent error using an integrated low-offset voltage-to-frequency converter. A separate analog-to-digital converter on the integrated circuit is used to measure battery voltage and temperature. Using the measurement inputs, the bqJunior runs a proven algorithm to accurately calculate remaining battery capacity and system run-time.
bqJunior compensates remaining battery capacity and run-times for battery discharge rate and temperature variations. Because the device performs the algorithm and data set calculations, there is no need to develop and incorporate code to implement those tasks in the host system processor, which helps reduce development time and total implementation cost. The host system processor simply reads the data set in the bqJunior to retrieve remaining battery capacity, run-time and other critical information that is fundamental to comprehensive battery and power management, including: available power, average current, temperature, voltage and time to empty and full charge. The bqJunior includes a single wire communications port (HDQ protocol) to communicate the data set to the system host controller, such as TI's OMAP1510 and OMAP5910 application processors.
The fuel gauge operates directly from a single Li-Ion cell and operates at less than 100uA. It features three low power standby modes to minimize battery consumption during periods of system inactivity. Other features include:
Low-offset voltage to frequency converter (VFC) for accurate charge and discharge counting
- Internal time-base for reduced component count
- On-chip configuration EEPROM for application specific parameters
- Programmable input/output port
The bqJunior takes advantage of TI's new LBC4 copper CMOS process node, which helps to achieve new levels of integration, low power and performance.
Availability, Packaging and Pricing
Samples of the bqJunior battery fuel gauge are currently available to select customers. Volume production is scheduled for the second quarter. The bqJunior device is packaged in an 8-pin TSSOP or QFN (3 mm x 4 mm) package. The part is priced at $2.55 per unit in quantities of 1,000.
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