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 L9963E battery monitoring and protection IC and ST’s automotive MCUs.

A Li-ion battery monitoring and protection chip, the L9963E can handle up to 14 Li-Ion battery cells and can be stacked in a vertical arrangement in order to monitor up to 31 battery packs – corresponding to a nominal battery voltage of several hundred volts.

Designed for monitoring cells and battery pack status through stack voltage measurement, cell voltage measurement, temperature measurement and coulomb counting, the L9963E sends the measurement data through a dedicated 16-bit ADC to an external microcontroller for charge balancing and to compute the State Of Health (SOH) and State Of Charge (SOC).

To further ease designs, the L9963E is universal communication interface compatible with transformer-or capacitor-based isolation techniques in BMS applications with devices working in different voltage domains.

A general-purpose SPI to isolated SPI transceiver, the L9963T creates a communication bridge between devices located in different voltage domains and can be configured either as Peripheral or as Controller of the SPI bus. Featuring an internal queue of 3 slots for the frames received on the SPI port and a queue of 20 slots for the ones received on the isolated SPI side, the L9963T can buffer and decouple two different clock domains.

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 on the final application’s requirements in terms of performance and safety level. The highest overall performance can be achieved with the SPC58 G Line, which offers up to three cores and memory sizes up to 6 Mbytes. It also ensures hardware security compliance with EVITA and SHE standards.