JAJSSA8 November 2023 BQ76905
PRODUCTION DATA
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, the internal logic is powered down, the protection FETs are all disabled, so no voltage is provided at the battery pack terminals. All protections, voltage, current, and temperature measurements are disabled, and no communications are supported. When the device exits SHUTDOWN, it reads parameters stored in OTP (which is programmed by TI), which effectively sets the default values for settings. After device power-up, settings can then be changed by the host writing device registers.
The device can enter SHUTDOWN mode when directed by the host through a subcommand. It can also be configured to enter SHUTDOWN mode automatically based on the top-of-the-stack voltage or the minimum cell voltage. The shutdown based on cell voltage does not apply to cell input pins not used for actual cells.
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 a programmable threshold.
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 measurements, evaluate those relative to enabled protections, and then enable FETs if conditions and settings 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, based on the configuration setting.
The BQ76905 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 is initiated, but the device detects the wakeup criteria is present, then the device stays in a "soft shutdown" state until the wakeup criteria is removed. While in a "soft shutdown," FETs are disabled, and protections and measurements are stopped. The device exits the "soft shutdown" when conditions allow the device to continue into SHUTDOWN mode. The host can stop the entry into SHUTDOWN mode through commands, and the device restarts operation with a full reset.