SLUUCP8 June 2024 BQ41Z50
The BQ41Z50 device provides an option for removable packs (that is, DA Config[NR] = 0) to enter SLEEP mode in-system. When the DA Config[IN_SYSTEM_SLEEP] = 1, the device will turn off CHG FET and PCHG FET if FET Options[SLEEPCHG] = 0 and enter SLEEP mode even if the OperationStatus()[PRES] = 1. This option ignores the PRES pin status only. Additionally, in this option, the SMBus low state is not a condition to enter SLEEP mode (instead, communication must not occur for Bus Timeout to enter SLEEP). All the other sleep conditions must be met for the device to enter SLEEP mode.
In IN SYSTEM SLEEP mode, it is possible to read the [SLPAC] and [SLPCC] flags if [IN_SYSTEM_SLEEP] = 1 and Bus Timeout = 0. This setting allows the gauge to enter SLEEP mode with active communication in progress.
Setting the Bus Timeout = 0 with [IN_SYTEM_SLEEP] can be used for testing purposes, but it is not recommended to set the Bus Timeout = 0 in the field. If Bus Timeout = 0, the device's sleep and wake conditions are strictly controlled by current detection. If the host system performs a low load operation periodically (for example, wireless detection in a tablet application), this small load current may be missed, introducing an error into remaining capacity tracking. Having a non-zero Bus Timeout setting enables the gauge to wake up by a communication and capture the current measurement.