Overvoltage protection for Li-ion batteries with regulated output supply

The Texas Instruments BQ2969 family is a high-accuracy, low-power overvoltage protector with a 3mA regulated output supply for Li-ion and LFP battery pack applications.

Each cell in a two-series to four-series cell stack is individually monitored for an overvoltage condition. Upon detection of an overvoltage condition on any cell, an internally fixed delay timer is initiated. Upon expiration of the delay timer, the output pin is triggered into an active state to indicate that an overvoltage condition has emerged.

The regulated output supply delivers up to 3mA output current to drive always-on circuits, such as an RTC oscillator. The family has a self-disable function that turns off the regulated output if any cell voltage falls below a programmable undervoltage threshold, thereby stopping battery drain.

The family provides extremely low power operation, drawing only 1.23µA during normal operation (excluding regulator load current) and dropping to 0.25uA when in an undervoltage condition. Even when in the undervoltage state, the device can still detect an overvoltage condition on any other cell (which can occur in an imbalanced pack) and can assert the output pin.