L9961 Battery Management System Solution for Li-Ion and Li-Polymer Cells

STMicroelectronics' L9961 plays a key role in complete battery pack monitoring, balancing, and protection systems based on Li-ion and Li-polymer cells having 3, 4, or 5 series configurations. The L9961 uses a high-precision ADC to provide cell voltage, stack voltage, and temperature conversion via external NTC. Voltage monitoring functions are cyclically performed with a programmable loop time. Stack current is also monitored via a high-accuracy CSA, continuously running and also performing Coulomb counting. Cell balancing is available and can be simultaneously activated on all cells. IC configuration and information exchange for SOC/SOH estimation are performed via I²C peripheral. From the safety point of view, L9961 guarantees protection of the battery pack fuse to prevent fire and explosion hazards, protection of the battery pack against over/undervoltage conditions and over/undertemperature, protection against overcurrent (both directions) and short-circuit in discharge events..

Features

• Very low current consumption in both deep-sleep mode (i.e., 2 μA) and standby mode (i.e., 5 μA)
• High accuracy in cell voltage measurements (i.e., maximum error of ±15 mV in the 1.5 V to 4.5 V range, for -40°C <T_J <+105°C) with over/undervoltage detection and balance undervoltage protection
• High accuracy in battery current measurements (i.e., maximum error of 0.25%) with Coulomb counting, overcurrent detection, and short-circuit in discharge protection
• Stack voltage monitoring with over/under voltage detection and plausibility check
• Pack temperature monitoring via NTC sensor with over/undertemperature detection and pack fuse management
• I²C peripheral for device programming and data transfers over I²C bus
• Hotplug robustness
• Embedded NVM for configuration parameters storage