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Fuel gauge operates without host-side fuel-gauging algorithms

Posted: 07 Dec 2004 ?? ?Print Version ?Bookmark and Share

Keywords:dallas semiconductor? ds2780? fuel gauge? li-ion? li-ion polymer?

Dallas Semiconductor introduced the DS2780 stand-alone fuel gauge that calculates remaining capacity for Li-ion and Li-ion polymer batteries without the need for host-side fuel-gauging algorithms. According to the company, this device greatly simplifies software development.

The device provides 16bit current measurement, 11bit voltage and temperature measurements, and on-chip nonvolatile memory to store cell characterization data and application performance parameters. It uses this measured and stored data to calculate the remaining capacity. Additionally, the DS2780's on-chip algorithms and status-reporting capabilities automatically send alerts to the host processor. This reduces the fuel gauge's amount of interaction with the processor and frees the processor for other operations, added the company.

Current is measured in the DS2780 by calculating the voltage drop across a low-value sense resistor. The product can be programmed to compensate the current-sense resistor to correct for variation in its value over temperature, allowing the use of lower cost sense resistors without compromising current measurement accuracy. To improve current-measurement accuracy even further, it also includes automatic current-offset correction and user-programmable gain compensation.

In addition, the DS2780 contains 40 bytes of EEPROM (24 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, which minimizes the number of pack contacts.

Typical applications for the DS2780 include digital still cameras, subnotebook computers, handheld PC-data terminals and 3G multimedia wireless handsets. This device is available in an 8-pin TSSOP package, and has prices starting at $2.60 (1,000-up, FOB USA).

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