SLUUCG7 April 2024 BQ76922
The timing of events in the BQ76922 device varies based on the specific event. Several events and their associated timing are described below. Timings described below do not include the delays related to individual protections, as described in their respective sections.
Event Description | Timing |
---|---|
Alarm Status()[SSA] asserted, ALERT pin asserted due to Alarm Status()[SSA]. | Fast response, in NORMAL or SLEEP modes |
Data (including cell voltages and CC2 Current()) calculated after measurements complete (except for temperature calculations based on thermistor voltage measurements). | Fast response, in NORMAL or SLEEP modes |
FET turn-off based on enabled protection fault, with Settings:Protection:CHG FET Protections A set to 0x98 or 0x18, and Settings:Protection:DSG FET Protections A set to 0x80 or 0xE4. | Fast response, in NORMAL or SLEEP modes |
CHG FET turn-on, and DSG FET changing from source follower mode to charge pump mode, based on current wake detector triggered while in SLEEP mode. | Fast response, in SLEEP mode |
FET turn-off based on enabled protection fault, with Settings:Protection:CHG FET Protections A not set to 0x98 or 0x18, and Settings:Protection:DSG FET Protections A not set to 0x80 or 0xE4. | Evaluated every 250ms in NORMAL mode, or every 1 second in SLEEP mode |
FET turn-on based on a pin (such as CFETOFF or DFETOFF deasserted) or command (such as ALL_FETS_ON() sent), while Settings:Manufacturing:Mfg Status Init[FET_EN] is set. | Evaluated every 250ms in NORMAL mode, or every 1 second in SLEEP mode |
Evaluation if SHUTDOWN mode should be entered (due to RST_SHUT held high, temperature beyond Power:Shutdown:Shutdown Temperature, or stack voltage below Power:Shutdown:Shutdown Stack Voltage, | Evaluated every 250ms in NORMAL mode, or every 1 second in SLEEP mode |
CC1 Current() is calculated | Evaluated every 250ms in NORMAL mode, or every 4 second in SLEEP mode |
Minimum, maximum, and average voltages calculated | Evaluated every 250ms in NORMAL mode, or every 1 second in SLEEP mode |
Temperatures calculated based on measured thermistor voltages | Evaluated every 250ms in NORMAL mode, or every 1 second in SLEEP mode |
PRECHARGE mode updated | Evaluated every 250ms in NORMAL mode, or every 1 second in SLEEP mode |
Alarm Status() other than [SSA] is updated, and ALERT pin asserted accordingly | Evaluated every 250ms in NORMAL mode, or every 1 second in SLEEP mode |
Evaluate whether OTP programming can proceed, in response to Permanent Failure status needing to be written, or MANU_DATA() write subcommand sent. | Evaluated every 250ms in NORMAL mode, or every 1 second in SLEEP mode |
Firmware safety checks (such as OCD3, temperature protections) and protection recovery checks | Evaluated every 1 second in NORMAL or SLEEP modes |
Firmware Permanent Failure checks | Evaluated every 1 second in NORMAL or SLEEP modes |
Evaluating entering or exiting SLEEP mode. This is separate from the FETs changing state when current is detected in SLEEP mode (fast response, as described above). When exiting SLEEP mode, this refers to the NORMAL mode measurement loop resuming. | Evaluated every 1 second in NORMAL or SLEEP modes |
Cell balancing (to determine if autonomous cell balancing should begin) | Evaluated every 1 second in NORMAL or SLEEP modes (limited in SLEEP by data available every Power:Sleep:Voltage Time interval) |
Cell balancing (to determine if active autonomous cell balancing should continue) | Evaluated every Settings:Cell Balancing:Cell Balance Interval in NORMAL or SLEEP modes (limited in SLEEP by data available every Power:Sleep:Voltage Time interval) |
RAM integrity check | Evaluated every 1 second in NORMAL or SLEEP modes |
Internal watchdog timer | Generates reset if firmware does not respond every 2 seconds in NORMAL and SLEEP modes, and in DEEPSLEEP mode when the LFO is operating. |