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Dallas Semi unrolls programmable battery fuel gauge

Posted: 14 Aug 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Dallas Semi? DS2790? fuel gauge? protector?

Dallas Semi fuel gauge and protector

Dallas Semiconductor recently launched a programmable 1-cell Li-ion fuel gauge and protector. Dubbed DS2790, this new product features integrated MAXQ microcontroller (MCU), program and data memory, and "accurate measurement system" for battery current, voltage and temperature. It provides an efficient platform for customizing single-cell battery fuel-gauging algorithms, said the company.

The new fuel gauge IC is designed for a single-cell Li+ battery pack. It is a microprocessor-based solution that features fuel-gauging capability and customization traditionally reserved for devices that serve battery packs with much higher cell counts and more complexity, such as those found in notebook computers. It is driven by a low-power 16bit MAXQ20 MCU with an accumulator-based 16bit RISC architecture. The processing core is supported by a 16-level hardware stack, which enables fast subroutine calling and task switching. Data can be quickly 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 DS2790 contains three types of memory: programming memory, data EEPROM and data RAM. The memory is arranged in Harvard-style architecture with separate address spaces for program and data memory. The 16Kbyte programming memory consists of 8Kbyte password-protected EEPROM and 8Kbyte ROM.

The DS2790 also provides precise current, accumulated current, voltage and temperature measurements. The 12bit-plus-sign current measurements are an average of 128 individual current samples. The current measurements are internally summed to produce the accumulated current with accuracy within 2 percent of full-scale measurement, four V over a range of 64mV.

A single-cell protector promises even greater performance-to-cost capability. The device's 1-cell Li+ protection circuitry is comprised of an autonomous state machine that provides the overvoltage, undervoltage and over-/underdischarge protection. Safety and reliability are increased because the protection function does not rely on the CPU and, therefore, does not depend on its loading to perform other functions.

Typical applications for the DS2790 include wireless handsets, high-end PDAs, digital video camcorders and digital still cameras. The device is available in 28-pin TSSOP and TDFN packages with prices starting at $2.50 (1,000-up, FOB USA).

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