Power Electronics

Li-ion Fuel Gauge Features Standalone Operation

Dallas Semiconductor augments its standalone fuel gauge product line with the DS2782 fuel gauge. The DS2782 uses the industry-standard 2-wire interface to communicate with the host. It calculates remaining capacity for Li+ and Li+-polymer batteries without the need for host-side fuel-gauging algorithms, thus greatly simplifying software development. Though it is optimized for single-cell applications, it can accommodate multicell applications with a few circuit modifications.

The DS2782 measures several battery parameters, including current, voltage, and temperature. Built-in current-offset correction and user-programmable gain compensation improve current measurement accuracy. In addition, the device can be programmed to compensate the current-sense resistor to correct variation in its value over temperature. This enables the use of less accurate, lower-cost sense resistors. Voltage measurements are 11-bit with a resolution of 4.88 mV over a range of 0 V to 4.992 V. Temperature measurements also are 11-bits and have a resolution of 0.125°C over the entire -40°C to +85°C operating range of the device.

Cell characterization data and application performance parameters used to calculate the remaining battery capacity are stored in 24 bytes of on-chip nonvolatile memory. An additional 16 bytes of nonvolatile memory are available for use by the host system or pack manufacturer. The DS2782 is available in an 8-pin TSSOP. Prices start at $2.60 each in lots of 1000.

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