SLUUBD4A April 2016 – November 2022 BQ27220
This mode is a halted-CPU state that occurs when an adapter or other power source is present to power the fuel gauge (and system), yet no battery has been detected. If enabled via the Operation Config B [BIEnable] bit, the fuel gauge detects battery insertion either through use of the thermistor network or the BIN pin. Alternatively, the host can use the BAT_INSERT() and BAT_REMOVE() subcommands to inform the battery presence or removal status. When battery insertion is detected, a series of initialization activities begin, which include: OCV measurement, setting the BAT_GD pin, and selecting the appropriate battery profiles.
Some commands, issued by a system processor, can be processed while the fuel gauge is halted in this mode. The gauge wakes up to process the command, then returns to the halted state awaiting battery insertion.