STMicro’s Battery-Management IC Ensures Long-Lasting Power for 10-Cell Packs

The latest battery management IC from STMicroelectronics integrates a 12-bit analog-to-digital converter (ADC) to accurately measure cell voltages and supports cell-balancing current of 70mA to ensure rapid voltage correction.

Designed for lithium-ion (Li-ion) and lithium-polymer (Li-Po) battery packs with up to 10 series-connected cells, the L9962 provides monitoring, balancing, and protection to optimize performance and enhance the safety, stability, and overall longevity. It is suitable for cordless power tools and other portable and semi-portable equipment, including medical devices, light electric vehicles like e-bikes and scooters, and backup energy storage such as UPS.

The L9962 measures individual cell voltages on a continuous cycle with programmable loop time and, when it detects overvoltage or undervoltage, it activates its cell balancing and protection functions. In addition, plausibility checking compares the total stack voltage with the number of cells. It also maintains voltage-measurement accuracy across the full operating-temperature range, ensuring cell voltages remain tightly aligned.

The L9962 integrates a high-accuracy current-sense amplifier for current measurements using Coulomb counting. By closely monitoring battery-pack current, the device can detect excessive charge and discharge currents and provide short-circuit discharge protection. It also maintains 0.25% current-measurement accuracy over the full temperature range, improving the overall accuracy of the BMS.

Thermal monitoring with an NTC thermistor provides accurate ratiometric measurements to detect battery-pack over-temperature and under-temperature.

The device integrates several other functions intended to reduce external component requirements, including battery-pack fuse management and configurable high-side and low-side pre-drivers for battery-pack relays. There is also a 3.3V low-dropout regulator (LDO), which remains turned on in standby mode, to provide power for external components such as a microcontroller (MCU) or indicator LEDs.

An I2C interface allows the host system to configure device parameters such as the voltage-measurement interval and to retrieve information such as the battery pack’s state-of-charge (SOC) and state-of-health (SOH).

The device’s ultra-low quiescent current maximizes runtime and permits power-saving modes, including 5µA standby and 2µA deep-sleep for products in transit.

The L9962 is packaged as a 7mm x 7mm 48-pin TQFP and priced at $2.89 each for orders of 1,000 units.