SLUUCY8 December 2023 BQ77307
SHUTDOWN mode is the lowest power mode of the BQ77307, 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.
The device can be configured to enter SHUTDOWN mode automatically based on the minimum top of stack voltage, the minimum cell voltage, or an excessive die temperature. 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, or if the internal die temperature exceeds Power:Shutdown:Shutdown Temperature, the SHUTDOWN mode sequence is automatically initiated. 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.
The BQ77307 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, based on the configuration setting.
When the device is wakened from SHUTDOWN, it requires approximately 10 ms for the internal circuitry to power up, load settings from OTP memory, perform initial evaluation of conditions relative to enabled protections, then to enable FETs if conditions and settings allow.
The BQ77307 wakes from SHUTDOWN if a voltage is applied at the TS or VC0 pins above a level of approximately 1.2 V. If the shutdown sequence has been initiated, but the device detects the wakeup criteria (either the TS or VCO pin voltage detected high) is present, then the device stays in a "soft shutdown" state until the wakeup criteria has been removed (meaning both the TS and VCO pin voltages must be detected low). While in "soft shutdown", FETs and protections are disabled. 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 0x0012 RESET()command can be written, and the device restarts operation as if returning from a POR.
When the SHUTDOWN mode sequence has been initiated by the stack voltage detected below Power:Shutdown:Shutdown Stack Voltage or a cell voltage detected below Power:Shutdown:Shutdown Cell Voltage, the device asserts the Alarm Raw Status()[SHUTV] bit and wait for 10 seconds to disable the protection FETs, then proceed toward SHUTDOWN mode. 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 prefers to abort the SHUTDOWN entry, it can send the 0x0012 RESET() command, and the device restarts with settings loaded from OTP.
When the device is wakened from SHUTDOWN, it requires < 10 ms for the internal circuitry to power up, load settings from OTP memory, evaluate conditions relative to enabled protections, then enable FETs if conditions allow.