SHUTDOWN mode is the lowest power mode of the BQ76905, which can be used for shipping or long term storage. In this mode, the device loses all register state information (except for what has been programmed into OTP by TI), the internal logic is powered down, the protection FETs are all disabled, so no voltage is provided at the battery pack terminals. All protections are disabled, all voltage, current, and temperature measurements are disabled, and no communications are supported. When the device exits SHUTDOWN mode, it reads any parameters stored in OTP. If the OTP has not been programmed (this is only supported by TI), the device powers up with default settings, and then settings can be changed by the host writing device registers.

Entering SHUTDOWN mode involves a sequence of steps. The sequence can be initiated manually by sending the 0x0010 SHUTDOWN() subcommand twice within 4 seconds. The device can also be configured to enter SHUTDOWN mode automatically based on the top of stack voltage or the minimum cell voltage. If the top-of-stack voltage falls below Power:Shutdown:Shutdown Stack Voltage or if the minimum cell voltage falls below Power:Shutdown:Shutdown Cell Voltage, the SHUTDOWN mode sequence is automatically initiated (this is only evaluated in NORMAL or SLEEP modes when measurements are being taken). The shutdown based on cell voltage only applies to cell input pins being used for actual cells, based on settings in Settings:Configuration:Vcell Mode.

While the BQ76905 is in NORMAL mode or SLEEP mode, the device can also be configured to enter SHUTDOWN mode if the internal temperature measurement exceeds Power:Shutdown:Shutdown Temperature.

When the SHUTDOWN mode sequence has been initiated by the 0x0010 SHUTDOWN() subcommand (twice within 4 seconds) or by stack voltage measured below Power:Shutdown:Shutdown Stack Voltage or a cell voltage measured below Power:Shutdown:Shutdown Cell Voltage, the device waits for 10 seconds to disable the protection FETs, then proceed toward SHUTDOWN mode. Sending the 0x0010 SHUTDOWN() subcommand a third time bypasses this delay. When SHUTDOWN mode is initiated in this manner, the device first transitions to NORMAL mode and blocks entrance to SLEEP mode. If the FETs were initially off (such as if the device was in DEEPSLEEP mode), the FETs remain off. At this first transition to NORMAL mode from SLEEP or DEEPSLEEP mode, the device clears the BatteryStatus()[FET_EN] bit, so if the FETs are disabled, they are not autonomously re-enabled. The host can send FET_ENABLE() to reassert this bit if desired. When the device transitions to NORMAL mode from DEEPSLEEP mode in preparation for entering SHUTDOWN, the device also effectively sets the FET_CONTROL()[DSG_OFF] and [CHG_OFF] bits, so the FETs remain disabled until the host elects to modify them.

During this 10 second shutdown delay, the device does not abort entering SHUTDOWN if the voltages rise back above the shutdown thresholds. If the host reads the system voltages and prefers to abort the SHUTDOWN entry, it can send either the 0x000E EXIT_DEEPSLEEP() or the 0x0012 RESET() commands, and the device restarts with default settings.

When the device is wakened from SHUTDOWN, it requires < 10 ms for the internal circuitry to power up, load settings from OTP memory, perform initial measurements, evaluate those relative to enabled protections, then to enable FETs if conditions allow.

The BQ76905 integrates a hardware overtemperature detection circuit, which determines when the die temperature passes an excessive temperature of approximately 120°C. If this detector triggers, the device automatically begins the sequence to enter SHUTDOWN if the Settings:Configuration:Power Config[OTSD] configuration bit is set.

The BQ76905 wakes from SHUTDOWN if a voltage is applied at the TS pin above a level of approximately 1 V or a voltage is applied at the VC0 pin above a level of approximately 1.2 V. If the shutdown sequence has been initiated, but the device detects the wakeup criteria is present, then the device stays in a "soft shutdown" state until the wakeup criteria has been removed. While in "soft shutdown", FETs are disabled, and protections and measurements are stopped. The device exits "soft shutdown" when conditions allow the device to continue into SHUTDOWN mode. If the host wants to abort the entry into SHUTDOWN mode, the EXIT_DEEPSLEEP() command can be written, and the device restarts operation as if returning from a POR.