Li+ fuel gauge IC with continuous internal self-discharge

The MAX17320 is a pack-side fuel gauge and protector IC for two to four series Lithium-ion (Li+) cells (2S-4S) and is part of a family of ICs equipped with Maxim Integrated’s patented ModelGauge m5 EZ algorithm that delivers accurate state-of-charge (SOC) readings, eliminating the need for battery characterisation for most common Li+ cells.

This fuel gauge also offers a low quiescent current (IQ), which features SHA-256 authentication to safeguard systems from counterfeit batteries.

For hand-held devices with 2S-4S Li+ batteries in the computing, internet of things (IoT), power tool, consumer, healthcare and mobile device categories, ensuring customer safety is top of mind for designers. Damaged or defective batteries may develop an internal cell leakage which can progressively get worse and can result in dangerous outcomes, including fire or explosion. This can endanger consumers and tarnish brand value for manufacturers. Stringent factory screening may prevent leaky cells from getting shipped out of the factory.

However, until now there were no solutions for detecting self-discharge that develops during normal usage of the battery. The MAX17320 warns the system and disables a leaky battery before a potentially hazardous outcome. This is in addition to the most advanced battery protection that allows fine tuning of voltage and current thresholds based on various temperature zones. The IC also provides a secondary protection scheme that permanently disables the battery by assisting a secondary protector or blowing a fuse in severe fault conditions.

As with any mobile device, manufacturers aim to deliver products that have longer battery life than the competition. Devices also need to have accurate SOC information to determine the remaining run-time. As part of a family of ICs with ModelGauge m5 algorithm, the MAX17320 allows designers to enable the longest run-time and avoid premature or sudden shutdown, while delivering accurate SOC.

The MAX17320 can run in an ultra-low-power mode, enabling the system to read the SOC instantly as it wakes up without being disconnected from the battery cells during shipment or when stored on the shelf. With a low IQ, the MAX17320 supports longer product shelf life.

Key advantages

• High protection: Ensures safe charging and discharging in 2S-4S Li+ battery applications by protecting against abnormal voltage, current and temperature conditions. Internal self-discharge detection provides systems with an early warning and cuts off potentially hazardous batteries. Delivers protection against cloning with SHA-256 authentication while providing unique or dynamic key for every battery.
• High accuracy: ModelGauge m5 algorithm delivers 40 percent better SOC accuracy than competitive offerings.
• Low IQ: Supports long product shelf-life and runtime with operating IQ that is 85 percent lower than the nearest competitor.

“It is important to ensure consumer safety for portable Li+ devices,” said Kevin Anderson, practice leader at Omdia. “Providing multiple levels of battery protection and safeguarding from counterfeit products will help designers prove their safety claims for their brands.” “Maxim Integrated’s fuel gauge ICs are the industry’s safest and most accurate,” said Bakul Damle, business management director, Mobile Power Business Unit at Maxim Integrated. “The MAX17320 ICs provide additional safety by detecting internal leakage and preventing potentially hazardous outcomes, while enhancing user experience through the industry’s highest accuracy for 2S-4S Li+ battery powered devices using Maxim Integrated’s ModelGauge m5 algorithm.”

The MAX17320 is available at Maxim’s website for $1.55 (1000-up, FOB USA); also available from authorised distributors. The MAX17320X2EVKIT# evaluation kit is available for $89.