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.
About the Author
Lee GoldbergLee Goldberg
Contributing Editor
Lee is the author of the popular PowerBites series.
Lee Goldberg is a self-identified “Recovering Engineer,” Maker/Hacker, Green-Tech Maven, Aviator, Gadfly, and Geek Dad. He spent the first 18 years of his career helping design microprocessors, embedded systems, renewable energy applications, and the occasional interplanetary spacecraft. After trading his ‘scope and soldering iron for a keyboard and a second career as a tech journalist, he’s spent the next two decades at several print and online engineering publications.
Lee’s current focus is power electronics, especially the technologies involved with energy efficiency, energy management, and renewable energy. This dovetails with his coverage of sustainable technologies and various environmental and social issues within the engineering community that he began in 1996. Lee also covers 3D printers, open-source hardware, and other Maker/Hacker technologies.
Lee holds a BSEE in Electrical Engineering from Thomas Edison College, and participated in a colloquium on technology, society, and the environment at Goddard College’s Institute for Social Ecology. His book, “Green Electronics/Green Bottom Line - A Commonsense Guide To Environmentally Responsible Engineering and Management,” was published by Newnes Press.
Lee, his wife Catherine, and his daughter Anwyn currently reside in the outskirts of Princeton N.J., where they masquerade as a typical suburban family.