Fuel-gauge ICs set new standard for Li-ion battery charge accuracy

By Warren Miller, contributing writer

The challenge of measuring the state of charge (SOC) of lithium-ion batteries is an issue for manufacturers of everything from smartphones and wearables to power tools and electric bikes. Accurately determining the amount of battery charge left in lithium-ion (Li-ion) batteries can go a long way toward improving their overall lifespan, reliability, and runtime. Maxim Integrated Products, Inc. recently announced a pair of new fuel-gauge ICs designed to provide market-leading accuracy of SOC measurements while decreasing time-to-market issues for manufacturers.

The MAX17262 single-cell and MAX17263 multi-cell fuel-gauge ICs both use the ModelGauge m5 EZ algorithm and standard coulomb counting to produce high-accuracy SOC measurements without the need for battery characterization, a costly and time-consuming process.

Key features:

• Provide accurate time-to-empty (1%) and time-to-full state-of-charge data across a wide range of load conditions and temperatures
• The ModelGauge m5 EZ algorithm eliminates the battery-characterization and calibration process
• Quiescent current of 5.2 µA for the MAX17262 and 8.2 µA for MAX17263 extends runtime
• Integrated Rsense current resistor (voltage and coulomb counting hybrid) reduces overall footprint and BOM cost and simplifies board layout
• At 1.5 × 1.5 mm, the MAX17262 is 30% smaller compared to using a discrete sense resistor with an alternate fuel gauge, and at 3 × 3 mm, the MAX17263 is the smallest in its class for lithium-ion-powered devices
• The single-/multi-cell MAX17263 also drives LEDs to indicate battery status on a pushbutton press or system status on system microcontroller commands

The MAX17262 integrates a Rsense current resistor that eliminates the need to use a larger discrete part, while the integrated LED controller in the MAX17263 offloads the functionality from the microcontroller and minimizes battery drain. The MAX17623 is a more apt solution for applications that don’t include a digital display, driving anywhere from 3 to 12 LEDs for battery and system status.

Both ICs feature low quiescent current levels (5.2 µA for the MAX17262, the lowest level in its class, and 8.2 µA for the MAX17263), allowing them to curtail current loss during extended periods of device standby time, a factor in battery-life degradation. Both ICs also implement a dynamic power feature that allows for maximizing system performance without resulting in a battery shutdown.

The MAX17262 and MAX17263 are priced at $0.95 and $1.49, respectively (1,000 pieces, FOB USA). Both parts are also available via select authorized distributors.

The MAX17262XEVKIT# and MAX17263GEVKIT# evaluation kits are each priced at $60. Support resources include the MAX1726x ModelGauge m5 EZ User Guide and Software Implementation Guide as well as Linux drivers.