The BQ2969T family is a high-accuracy, low-power second-level overvoltage and overtemperature protector with a 3mA regulated output supply and control / PTC input for Li-ion and LiFePO₄ (LFP) battery pack applications.

Each cell in a 2-series to 4-series cell stack is individually monitored for an overvoltage condition by comparing the actual cell voltage to an overvoltage threshold V_OV. The overvoltage threshold is preprogrammed at the factory, with a range between 3.6V to 5.2V. The device initiates an internal fixed-delay timer when an overvoltage condition is detected on any cell. Upon expiration of the delay timer, the output pin is triggered into an active state to indicate that an overvoltage condition has occurred. The output pin can be configured as active-high, open-drain active pulldown, or open-drain inactive pulldown. The device recovers from the overvoltage condition when all cell voltages are detected below the overvoltage threshold by a hysteresis level, which can be programmed to 150mV or 300mV. Alternatively, the output pin can be programmed to latch and not recover whenever the output pin is activated.

The regulated output supply is programmable from 1.5V to 3.8V and delivers up to 3mA output current to drive always-on circuits, such as a real-time clock (RTC) oscillator. The BQ2969T family has a self-disable function to turn off the regulated output if any cell voltage falls below a programmable undervoltage threshold, thereby preventing drain on the battery. This undervoltage threshold can be programmed over a range from 1V to 4.15V.

The BQ2969T family includes a CTL pin which can be used to assert the OUT pin upon demand. The device also supports overtemperature (OT) protection when a PTC thermistor is attached between the CTL and VDD pins on the device.

The BQ2969T 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 still monitors cell voltages and can detect an overvoltage condition on any other cell (which can occur in an imbalanced pack) and assert the output pin. Similarly, in the undervoltage state, the device still monitors the CTL pin voltage and can detect an overtemperature condition when a PTC is used, and assert the output pin.