The DS2780 calculates remaining capacity for Li-Ion and Li-Ion polymer batteries without the need for host-side fuel-gauging algorithms. Thus, the DS2870 greatly simplifies software development.

The device provides 16-bit current measurement, 11-bit voltage and temperature measurements, and on-chip nonvolatile memory to store cell characterization data and application performance parameters. The DS2780 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 device’s amount of interaction with the processor and frees the processor for other operations.

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

Additionally, 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.

The device is available in a tiny eight-pin TSSOP package. It’s small enough to fit on the side of a prismatic battery cell. Prices start at $2.60.

Dallas Semiconductor Corp.
www.maxim-ic.com