The BQ76905 integrates an extensive primary protection subsystem which can monitor a variety of parameters, initiate protective actions, and autonomously recover based on conditions. The device also includes a wide range of flexibility, such that the device can be configured to monitor and initiate protective action, but with recovery controlled by the host processor, or such that the device only monitors and alerts the host processor whenever conditions warrant protective action, but with action and recovery fully controlled by the host processor.

The protection subsystem includes a suite of individual protections which can be individually enabled and configured, including cell undervoltage and overvoltage, overcurrent in charge, two separate overcurrent in discharge protections, short circuit current in discharge, cell overtemperature and undertemperature in charge and discharge, internal die overtemperature, and a host processor communication watchdog timeout. The overcurrent in charge and discharge and short circuit in discharge protections are based on comparator decisions, while the remaining protections (such as those involving cell voltage, temperature, and host watchdog) are based on ADC measurement or logic operation. The device integrates NFET drivers for low-side CHG and DSG protection FETs, which can be configured in a series or parallel configuration, and can also be used in pulse-width modulation mode to manually implement precharge or predischarge functionality.