A battery management system (BMS) is an electronic system that manages a rechargeable battery (cell or battery pack) with the aim of improving its overall performance in terms of energy storage and battery life. The BMS protects the battery from operating outside the specifications, balances it, monitors the health of the cells and communicates the battery status to higher-level systems.

STMicroelectronics provides a range of integrated circuits allowing to build up battery management systems for Lithium Ion batteries. ST’s BMS solution demonstrates the benefits of a battery management system for automotive applications, based on the L9963 battery monitoring and protection IC and ST’s automotive MCUs.

The L9963 can handle up to 14 Li-Ion battery cells and can be stacked in a vertical arrangement in order to monitor up to 15 battery packs – corresponding to a nominal battery voltage of several hundred volts. The IC monitors voltage, current and temperature at single cell or stack level with a resolution of 16 bit.

The L9963 is ideally seconded by a microcontroller of the SPC5 family of automotive MCUs, performing the cell balancing and state of health (SOH) and state of charge (SOC) computation based on the data collected through one or several L9963.

The solution proposed here is built with a high-performance MCU from the SPC57 4S Line, featuring up to 1.5 Mbytes of Flash memory and 128 Kbytes of RAM. The MCU carries two CAN-FD interfaces, 8 enhanced 12-bit ADCs with extensive triggering capabilities supports ASIL-D functional safety standards and is available in QFP100 packages for operating temperatures up to 150°C.

The presented implementation can be adapted to a wide range of ST’s automotive MCUs depending of the final application’s requirements in terms of performance and safety level. Highest overall performance can be achieved with the SPC58 G Line, with its up to three cores and memory sizes up to 6Mbyte. It adds hardware security compliance with EVITA and SHE standards.

A further benefit of the L9963 is universal communication interface compatible with transformer-based or capacitor-based isolation techniques in in BMS applications with devices working in different voltage domains.