BQ769x0 consists of three major subsystems: Measurement, Protection, and Control. These work together to ensure that the fundamental battery pack parameters—voltage, current and temperature—are accurately captured and easily available to a host controller, while ensuring a baseline or secondary level of hardware protection in the event that a host controller is unable or unavailable to manage certain fault conditions.

• The Measurement subsystem’s core responsibility is to digitize the cell voltages, pack current (integrated into a passed charge calculation), external thermistor temperature, and internal die temperature. It also performs an automatic calculation of the total battery stack voltage, by simply adding up all measured cell voltages.
• The Protection subsystem provides a baseline or secondary level of hardware protections to better support a battery pack’s FMEA requirements in the event of a loss of host control or simply if a host is unable to respond to a certain fault event in time. Integrated protections include pack-level faults such as OV, UV, OCD, SCD, detection of an external secondary protector fault, and internal logic “watchdog”-style device fault (XREADY). Protection events will trigger toggling of the ALERT pin, as well as automatic disabling of the DSG or CHG FET driver (depending on the fault). Recovery from a fault event must be handled by the host microcontroller.
• The Control subsystem implements a suite of useful pack features, including direct low-side NCH FET drivers, cell balancing drivers, the ALERT digital output, an external LDO and more.

The following sections describe each subsystem in greater detail, as well as explaining the various power states that are available.