It is suitable for battery packs up to 25V and provides monitoring, balancing and protection for lithium batteries. Typical applications are in back up energy storage systems, uninterruptible power supplies, portable and semi-portable equipment, medical devices and cordless power tools.

The L9961 has a dual pre-driver for controlling battery-pack safety relays. This can be programmed for high side and low side connection. An embedded non-volatile memory for configuration data relieves the microcontroller from reprogramming the device at start up each time. There is also an I2C interface which handles configuration and host communication to share battery state of charge and state of health information.

The controller also has a high resolution ADC and current sense amplifier to sense cell voltages with an accuracy of ±15mV and battery current to within 0.25%. These measurements are used for passive cell balancing and coulomb counting. Safety features include over-voltage and under-voltage detection, balance under-voltage protection, over-current detection and short-circuit in-discharge protection.

When an external thermistor is connected, the L9961 monitors pack temperature via over/under-temperature detection and pack-fuse management. The L9961 is also robust enough to support hot plugging.

The L9961 consumes minimal energy from the battery pack. It has two power-saving modes with current consumption of 2μA in deep sleep mode and 5μA in standby. An integrated voltage regulator remains active to resume operation quickly.

The controller is in production and is available now in a 32-lead 5.0 x 5.0 x 1.0mm VFQFPN package.

Visit STMicroelectronics at PCIM Europe 2023 – Hall 7 - 302