The BQ76905 device supports four operational modes, to support optimized features and power dissipation, with the device able to transition between modes either autonomously or controlled by a host processor.

• NORMAL mode: In this mode, the device performs frequent measurements of system current, cell voltages, internal and thermistor temperature, and various other voltages, operates protections as configured, and provides data and status updates. Battery protections are enabled, and the FET drivers are typically enabled (in the absence of any protection fault).
• SLEEP mode: In this mode, the device performs measurements, calculations, and data updates at adjustable time intervals. Between the measurement intervals, the device is operating in a reduced power stage to minimize total average current consumption. Battery protections are still enabled, and the FET drivers are typically enabled (in the absence of any protection fault).
• DEEPSLEEP mode: In this mode, the FET drivers are disabled, all battery protections are disabled, and no current or voltage measurements are taken. The REGOUT LDO can be kept powered, in order to maintain power to external circuitry, such as a host processor. Communications using I²C are still active.
• SHUTDOWN mode: The device is completely disabled (including the internal 1.8 V and REGOUT LDOs), the CHG and DSG FETs are both disabled, all battery protections are disabled, and no measurements are taken. This is the lowest power state of the device, which may be used for shipment or long-term storage. All register settings are lost when in SHUTDOWN mode.

The device also includes a CONFIG_UPDATE mode, which is used for parameter updates. Transitioning between operational modes is shown in Figure 7-6.

Figure 7-6 BQ76905 Operational Power Modes