Battery management controller extends life of lithium batteries
To enhance the performance, longevity and safety of lithium-ion and lithium-polymer (Li-ion and Li-polymer) batteries, STMicroelectronics has developed the L9961 battery management system. ST claims it provides market-leading accuracy and flexibility and is suitable for battery packs up to 25V.
The L9961 provides monitoring, balancing and protection of batteries for a variety of applications which require the high energy density of lithium batteries, such as back-up energy storage systems, uninterruptible power supplies, portable and semi-portable equipment, medical devices and cordless power tools.
The battery management system device includes a dual pre-driver for controlling battery pack safety relays, which 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 each start up. An I2C interface handles configuration and host communication to share battery state of charge and state of health status.
It also includes a high resolution ADC and current sense amplifier, enabling the L9961 to sense cell voltages with an accuracy of ±15mV and battery current to within 0.25 per cent. The measurements enable passive cell balancing and coulomb counting. They also support safety features including 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 performs pack temperature monitoring with over- / under-temperature detection and pack-fuse management. The L9961 is also highly robust to support hot plugging, said STMicroelectronics.
Although the L9961 extends battery life and increases safety yet consumes minimal energy from the battery pack, said ST. Two power-saving modes cut the current consumption down to 2.0 microA in deep sleep and 5.0 microA in standby with the integrated voltage regulator active to resume operation quickly.
The L9961 is in production and is available now in a 32-lead 5.0 x 5.0 x 1.0mm VFQFPN package.
