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New stand-alone fuel gauge from Dallas

Posted: 24 Jan 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Dallas Semiconductor? DS2781? fuel gauge?

Dallas Semiconductor introduced the DS2781 stand-alone fuel gauge. Operating directly from a 2.5V to 10V power source, the DS2781 calculates remaining capacity for 1- or 2-cell Li+ and Li+ polymer battery packs. This device includes 16-bit current measurement, and 11-bit voltage and temperature measurements. On-chip nonvolatile memory stores cell characterization data and application performance parameters. The company explained that the DS2781 uses this measured and stored data to calculate the remaining battery capacity. Additionally, the on-chip algorithms and status reporting capabilities reduce the amount of interaction necessary between the device and the host processor. Software development is thus greatly simplified, added Dallas.

The DS2781 measures current by calculating the voltage drop across a low-value sense resistor. Programming can compensate the current-sense resistor to correct for variation in its value over temperature, thus allowing use of lower cost sense resistors without compromising current measurement accuracy. To improve current measurement accuracy even further, the DS2781 also provides automatic current-offset correction and user-programmable gain compensation.

In addition, the DS2781 contains 40 bytes of EEPROM24 bytes to store the cell characterization data and application parameters, and 16 bytes for use by the host system or pack manufacturer. Communication between the device and the host is handled through a 1-Wire interface, reducing the number of pack contacts to a single wire.

The DS2781 fuel gauge is available in a Pb-free 8-pin TSSOP package. Prices start at $2.90 (1,000-up, FOB USA).

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