Overvoltage protector for 2- to 4-series cell Li-Ion batteries with CTR or PTC function

The BQ2969T family is a high-accuracy, low-power

overvoltage 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. An internal fixed-delay timer

is initiated upon detection of an overvoltage condition 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 regulated output supply 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.

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 exceptionally 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.