Battery Fuel Gauge Enables Complete Customization of Fuel-Gauge Algorithms for 1- or 2-Cell Applications
DALLAS, TX—March 15, 2007—Dallas Semiconductor, a wholly owned subsidiary of Maxim Integrated Products (NASDAQ: MXIM), introduces the DS2792 programmable fuel gauge for 1- or 2-cell applications. Integrated into the DS2792 are a MAXQ® microcontroller; generous program and data memory; and an accurate measurement system for battery current, voltage, and temperature. These features provide the ability to greatly customize fuel-gauging algorithms in battery-powered products.
At the heart of the DS2792's computing core is the low-power, 16-bit MAXQ20 microcontroller with its advanced, accumulator-based, 16-bit RISC architecture. Because the DS2792's instructions contain both the operation code and data, its fetch and execution operations are completed in one cycle without pipelining. The processing core is supported by a 16-level hardware stack, which enables fast subroutine calling and task switching. Data can be quickly and efficiently manipulated with three internal data pointers. Multiple data pointers allow more than one function to access data memory without having to save and restore data pointers each time.
To allow the user to program proprietary algorithms, the DS2792 contains three types of memory: programming memory, data EEPROM, and data RAM. The memory is arranged in a Harvard architecture, with separate address spaces for program and data memory. The 8k words of programming memory consists of 4k words of password-protected EEPROM and 4k words of ROM. The inclusion of EEPROM allows the devices to be reprogrammed, which simplifies and reduces the cost of development and field upgrades. The data EEPROM consists of 64 words and is available for storing important data such as charge parameters, cell characteristics, and manufacturing data that should remain unaffected by severe battery depletion, accidental shorts, or ESD events. The data RAM is 256 words and is used for temporary data storage.
The DS2792 also provides precise current, accumulated-current, voltage, and temperature measurements. Current measurements are internally summed to calculate the accumulated current, which is accurate to within 0.5% ±4.0µV over a range of ±64mV. Using a 15mOhm sense resistor, this current accuracy translates to within 0.5% ±267µA over a 4.2A range. The DS2792 measures voltage as a 10-bit value over a 0 to 4.99V range with a resolution of 4.88mV. An on-chip temperature sensor measures the temperature of the battery and reports the results as a 10-bit value with a resolution of 0.125°C. All measured data and any password-protected reprogramming of the EEPROM memory can be communicated to the host through the DS2792's UART interface.
Typical applications for the DS2792 include digital video cameras, SLR digital still cameras, sub-notebook and ultra-portable PCs, industrial PDAs, and handheld GPS devices. The DS2792 is available in an 8mm x 4mm, 28-pin, lead-free TDFN package. Prices start at $3.28 (1000-up, FOB USA).
