Battery Fuel Gauge Monitors Current, Voltage, and Temperature for Under $1*
DALLAS, TX-October 19, 2005-Dallas Semiconductor (NASDAQ: MXIM) introduces the DS2745, a low-cost Li+ battery monitor with an I2C** interface. Mounted on either the host side or the battery-pack side of the application, the DS2745 provides current, accumulated current, voltage, and temperature measurements -- all the necessary data to monitor battery capacity. Additionally, with a suggested resale of $0.98*, the device is ideal for cost-sensitive applications.
Current is measured bidirectionally over a dynamic range of ±51.2mV with a resolution of 1.56 microvolts by monitoring the voltage drop across an external sense resistor. Assuming a 15 milliohm sense resistor, the current-sense range is ±3.4A with a 1 LSB resolution of 104 microamps. Current measurements are performed at regular intervals and accumulated with each measurement to support accurate coulomb counting. Battery voltage is measured through a dedicated voltage-sense input and reported in a two-byte register with 11-bit (4.88mV) resolution. On-chip temperature measurement is reported in a two-byte register with a resolution of 0.125 degrees Celsius.
A standard I2C interface with software-programmable address gives the controlling microprocessor access to all data and status registers in the DS2745.The device operates with an active power consumption of less than 70 microamps and reverts to an ultra-low power consumption of less than 1 microamp when in sleep mode. This sleep mode conserves energy when the cell pack is not in use.
Typical applications for the DS2745 include cellular phones, GPS, PDAs, and other handheld products. The device is available in a tiny 8-pin microMAX® package.
microMAX is a registered trademark of Maxim Integrated Products, Inc.
*100K-up recommended resale. Prices are for design guidance and are FOB USA. International prices will differ due to local duties, taxes, and exchange rates.
**Purchase of I2C components from Maxim Integrated Products, Inc., or one of its sublicensed Associate Companies, conveys a license under the Philips I2C Patent Rights to use these components in an I2C system, provided that the system conforms to the I2C Standard Specification defined by Philips.
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