SLAAEV0 July   2026 BQ79616-Q1

 

  1.   1
  2.   Abstract
  3. 1Basic Principle of Reverse Wake-up for BQ79616
    1. 1.1 Basic Principle of Reverse Wake-up Implemented by BQ79616 and BQ79600
    2. 1.2 OVUVOTUT Function of BQ79616
    3. 1.3 Logic for BQ79600 to Implement Reverse Wake-up
  4. 2How to Configure BQ79616 and BQ79600 to Achieve Reverse Wake-up Function
    1. 2.1 Configuration for BQ79616 to Implement Reverse Wake-up Function
    2. 2.2 Configuration for BQ79600 to Implement Reverse Wake-up Function
    3. 2.3 Other Configurations for BQ79600 and BQ79616 Prior to Entering Sleep
  5. 3Testing of Reverse Wake-up Based on EVM Board
    1. 3.1 Reverse Wake-up Test with BQ79600 Operating in Sleep Mode
    2. 3.2 Reverse Wake-up Test with BQ79600 Operating in Shutdown Mode
  6. 4Summary
  7. 5References

1.3 Logic for BQ79600 to Implement Reverse Wake-up

During the reverse wake-up process, the BQ79600 can operate in Sleep mode or Shutdown mode with the Sniff function enabled.

If the BQ79600 operates in Sleep mode to realize reverse wake-up, the BQ79600 needs to enable the INH function, whereas the Heartbeat tone function can be selectively enabled. After entering Sleep mode, the communication module of the BQ79600 monitors whether a Fault tone is received at all times. Once a Fault tone is detected, the BQ79600 pulls the INH pin high, and the INH serves as a hardware wake-up signal to wake up the BMS SBC or PMIC power management chip. After being woken up, the SBC/PMIC continues to wake up the MCU, which in turn wakes up the BQ79600 and BQ79616 to confirm the cause of the reverse wake-up after data interaction. As shown in the figure below, the BQ79600 switches from Sleep mode to active mode.

Logic of BQ79600 Operation Mode SwitchingFigure 1-7 Logic of BQ79600 Operation Mode Switching

The BQ79600 can also operate in Shutdown mode, provided that its Sniff function is enabled before entering Shutdown mode. As shown in the switching logic among Shutdown mode, VALIDATE mode, and ACTIVE mode in the figure above, when a fault occurs in the battery system and the Fault tone is relayed to the BQ79600, the first Fault tone triggers the logic of SNIF Det=1, thereby prompting the BQ79600 to enter VALIDATE mode. After entering VALIDATE mode, CVDD is pulled high, but the INH is not pulled high immediately at this point. The chip waits for a duration of tVALID_DURATION. If a second Fault tone is detected, the BQ79600 pulls INH high to reverse-wake the BMS. Otherwise, the BQ79600 switches from VALIDATE mode back to Shutdown mode, CVDD is pulled low, and the chip continues to await the next Fault tone.

Note: After the BQ79600 enables the Sniff function and enters Shutdown mode, the BQ79600 no longer transmits the Heartbeat tone to the S1 BQ79616; therefore, the Heartbeat tone fault detection of the S1 BQ79616 needs to be masked.

The enabling principle of INH is illustrated in Figure 1-8, which shows the functional block diagram of the BQ79600. After a Fault tone is detected at COMH/L, the switch tube between INH and BAT is turned on, and INH is pulled up to BAT. If the BAT supply is 12V, a resistor divider method must be used after INH to step down the voltage to 5V or 3V to wake up the SBC/PMIC.

Note: The power consumption of the BQ79600 operating in Sleep mode is slightly higher than that in Shutdown mode. Shutdown mode saves power consumption but loses the diagnostics of the direct communication line from the BQ79600 to the first BQ79616. This is because during the sleep process, the BQ79600 in Shutdown mode no longer transmits or detects the Heartbeat tone.
BQ79600 function block diagramFigure 1-8 BQ79600 function block diagram