Analog Devices Inc./Maxim Integrated

The DS2781 remains in production, however, for new projects, we recommend ModelGauge m5MAX17215fuel gauge.The DS2781 measures voltage, temperature, and current, and estimates available capacity for rechargeable Lithium-Ion and Lithium-Ion Polymer batteries. Cell stack characteristics and application parameters used in the calculations are stored in on-chip EEPROM. The available capacity registers report a conservative estimate of the amount of charge that can be removed given the current temperature, discharge rate, stored charge and application parameters. Capacity estimation is reported in milliamp hours remaining and percentage of full.ApplicationsCommercial Two-Way RadiosDigital Video CamerasIndustrial PDAs and Handheld PC Data TerminalsPortable GPS Navigation Systems

The DS2786B estimates available capacity for rechargeable Li-ion (Li+) and Li+ polymer batteries based on the cell voltage in the open-circuit state following a relaxation period. The open-circuit voltage (OCV) is used to determine relative cell capacity based on a lookup table stored in the IC. This capability makes accurate capacity information available immediately after a battery pack is inserted. During periods of moderate to high rate discharging, which preclude OCV measurements, the DS2786B uses coulomb counting as a secondary means of estimating relative capacity.Remaining capacity is reported in percent, along with cell voltage, current, and temperature information. Cell characteristics and application parameters used in the calculations are stored in on-chip EEPROM.The DS2786B is intended for use on the host side of portable devices, though it can also be mounted within a battery pack. Measurement and estimated capacity data are accessed through an I²C interface. Temperature data is available from an on-die sensor. Resistance measurements of a pack identification resistor and pack thermistor are supported by ratiometric measurements on two auxiliary inputs.The DS2786B comes in a 10-pin, lead-free, TDFN 3mm x 3mm package with an exposed pad (EP).Applications3G Multimedia Wireless HandsetsDigital Audio (MP3) PlayersDigital Still Cameras