Features
• 2 μA shipment - DEEP SLEEP mode current and 5 μA standby consumption
(with VREG LDO active) standby consumption (with VREG LDO active)
• Integrated 3.3 V VREG LDO for supplying MCU and LEDs
• Measures cell voltage (3 to 5 cells), with over/undervoltage detection and
balance undervoltage protection
• 12-bit voltage measurement with maximum error of ±15 mV in the [1.5–4.5] V
range, for -40 °C < TJ < 105 °C
• Measures stack voltage, with over/under voltage detection and plausibility check
vs. sum of cells
• Measures pack temperature via NTC, with over/undertemperature detection
• Ratiometric temperature measurement with ±0.8% max. gain error in the [0.2–
VREG] V range, for -40 °C < TJ < 105 °C
• Measures battery current, with Coulomb counting, overcurrent (both directions)
and short-circuit in discharge protection.
• 16-bit signed current measurement with 0.1% full scale error at room
temperature
• I2C peripheral for device programming and data transfers over I2C bus
• Cell balancing supporting up to 70 mA per cell
• Dual configurable HS/LS predriver for pack relay management
• Pack fuse management
• Embedded NVM for configuration parameters storage
• High hotplug robustness

Description
L9961 is part of a complete battery pack monitoring, balancing, and protecting system for Li-Ion and Li-Polymer
cells in 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
performing also 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. The IC
also integrates a dual pre-driver programmable in both HS/LS configurations for driving pack relays. L9961 also
implements battery pack fuse protection to prevent fire and explosion hazards. A 3.3 V regulator with a high
current capability is available for supplying pack controller and other external circuitry in both standby and normal
operation modes. The IC protects the battery pack against over/under voltage conditions and monitors for over/
under temperature. It also features protection against overcurrent (both directions) and short-circuit in discharge
events. Safety-relevant configurations can be stored in the internal NVM to avoid re-programming the device at
each wakeup.

Applications
• Cordless power tools
• Backup energy storage systems and UPS
• Light electric vehicles (e-bikes, scooters, etc)
• Portable and semi-portable equipment
• Medical equipment