5.1µA Multi-Cell Fuel Gauge with ModelGauge m5 EZ

The MAX17261 is an ultra-low power fuel gauge IC which implements the Maxim ModelGauge™ m5 algorithm. The IC monitors a multiple-series cell battery pack with an external resistor divider.

The ModelGauge m5 EZ algorithm makes fuel gauge implementation easy by eliminating battery characterization requirements and simplifying host software interaction. The algorithm provides tolerance against battery diversity for most lithium batteries and applications.

The algorithm combines the short-term accuracy and linearity of a coulomb counter with the long-term stability of a voltage-based fuel gauge, along with temperature compensation to provide industry-leading fuel gauge accuracy. The IC automatically compensates for cell-aging, temperature, discharge rate, and provides accurate state-of-charge (SOC) in percentage (%) and remaining capacity in milliampere-hours (mAh) over a wide range of operating conditions. As the battery approaches the critical region near empty, the algorithm invokes a special correction mechanism that eliminates any error. The IC provides accurate estimation of time-to-empty and time-to-full and provides three methods for reporting the age of the battery: reduction in capacity, increase in battery resistance, and cycle odometer.

The IC provides precision measurements of current, voltage, and temperature. The temperature of the battery pack is measured using an internal temperature sensor or external thermistor. A 2-wire I²C interface provides access to data and control registers. The IC is available in a tiny lead-free 0.4mm pitch, 1.5mm x 1.5mm, 9-pin WLP package and 3mm x 3mm, 14-pin TDFN package.