SLEEP mode is a reduced functionality state that can be optionally used to reduce power dissipation when there is little or no system load current or charging in progress, but still provides voltage at the battery pack terminals to keep the system alive. At initial power up, the configuration setting determines whether the device can enter SLEEP mode. After initialization, SLEEP mode can be allowed or disallowed using subcommands. The device includes a status bit, available through a command, which indicates whether the device is presently in SLEEP mode.

When the magnitude of the current measurement falls below a programmable current threshold, the system is considered in relax mode, and the device will autonomously transition into SLEEP mode, if settings permit. During SLEEP mode, comparator-based protections operate the same as during NORMAL mode. Measurements of current, voltage, and temperature are taken using the ADC and coulomb counter at programmable intervals.

The device will exit SLEEP mode if a protection fault occurs, or current begins flowing, or through a subcommand. The current is checked approximately every 2.44 ms and, if it exceeds a programmable level in magnitude, the device transitions back to NORMAL mode.

The device also includes a 10-second hysteresis on the SLEEP mode entrance to avoid the device quickly entering and exiting SLEEP mode based on a dynamic load. After transitioning from SLEEP mode to NORMAL mode, the device does not enter SLEEP mode again for 10 seconds unless overridden by a subcommand. For more details, see the BQ76905 Technical Reference Manual.