The BQ76907 integrates a DEEPSLEEP mode, which is a low power mode that allows the REGOUT LDO and/or the programmable timer to remain powered, but disables most other subsystems. In this mode, the protection FETs are all disabled, so no voltage is provided at the battery pack terminals. All protections are disabled, and all voltage, current, and temperature measurements are disabled. Exceptions to this are the REGOUT Check and LFO Integrity Check, which can still detect a fault, generate a status flag, and can result in the device transitioning to SHUTDOWN mode, depending on settings.

DEEPSLEEP mode can be entered by sending the 0x000F DEEPSLEEP() subcommand twice in a row within a 4-sec time window. The device exits DEEPSLEEP mode and return to NORMAL mode if the 0x000E EXIT_DEEPSLEEP() subcommand is sent, or if a rising edge is generated at the TS pin or VC0 pin. In addition, if the internal 1.8 V LDO goes into power-on-reset (which can occur if the BAT pin voltage falls to an excessively low level) or the internal hardware overtemperature detector detects an excessive die temperature, the device transitions to SHUTDOWN mode.

When the device exits DEEPSLEEP mode, it first completes a Startup Sequence measurement and evaluates conditions relative to enabled protections, to ensure that conditions are acceptable to proceed to NORMAL mode.

The REGOUT LDO maintains its power state when entering DEEPSLEEP mode. The LFO is disabled during DEEPSLEEP mode based on the setting of Settings:Configuration:Power Config[DPSLP_LFO]. If the LFO is powered down, it is wakened by I²C communications, which can result in a longer than normal clock stretch before the device responds.

Other than the 0x000E EXIT_DEEPSLEEP() subcommand, communications with the device over the serial interface do not cause it to exit DEEPSLEEP mode. However, since no measurements are taken while in DEEPSLEEP mode, there is no new information available for readout. To collect measurement data without powering the system the user can do the following:

1. Send the 0x68 FET_CONTROL() command to keep the FETs disabled.
2. Send the 0x000E EXIT_DEEPSLEEP() subcommand to transition back into NORMAL mode.
3. Wait for a measurement cycle to complete by monitoring the 0x62 Alarm Status()[ADSCAN] or 0x62 Alarm Status()[FULLSCAN] bits.
4. Read the data.
5. Send the 0x000F DEEPSLEEP() subcommand twice within 4 seconds to return to DEEPSLEEP mode.
6. Send the 0x68 FET_CONTROL() command to unblock the FETs from being enabled when DEEPSLEEP mode is exited in the future.

If the LFO is programmed to be off in DEEPSLEEP mode, I²C communications cause it to power up at each transaction. To avoid a long clock stretch at every transaction in a short burst of transactions, the LFO includes a hysteresis such that it does not power back down after being wakened in DEEPSLEEP for approximately 25 ms.