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

1.2 OVUVOTUT Function of BQ79616

To achieve the reverse wake-up function, the OVUVOTUT function needs to be configured before the BQ79616 enters Sleep mode, so as to implement its monitoring of battery pack voltage and temperature in Sleep mode. After entering Sleep mode, other modules are deactivated, and only the OVUVOTUT module and communication module continue to operate. The power consumption of the chip in Sleep mode primarily includes the power consumption of the protection module and the communication module.

The implementation logic for the OVUV function of the BQ79616 is shown in the figure below. After configuring the OVUV thresholds via registers, the chip's OVUV DAC generates the corresponding analog voltages to the input terminals of the comparators. The other terminal of the comparator is connected to the cell voltage through a MUX and a BCI shifter. When a cell voltage exceeds the configured threshold, the OVUV fault is asserted.

Block Diagram of BQ79616 OVUV FunctionFigure 1-2 Block Diagram of BQ79616 OVUV Function

By the same token, the implementation logic for the OTUT function is shown in the figure below. The divided voltage between the pull-up resistor and the NTC sampled by the GPIO port is compared against the OTUT threshold via a comparator. An OTUT fault bit is asserted after an OTUT event occurs. The OTUT thresholds are configured in terms of percentage. A threshold percentage configuration of 50% means that after the NTC resistance (thermistor) at a certain temperature divides the voltage with the pull-up resistors (R1, R2), the voltage input to the GPIO equals 50% of the TSREF voltage.

Block Diagram of BQ79616 OTUT FunctionFigure 1-3 Block Diagram of BQ79616 OTUT Function
BQ79616 Temperature Sampling CircuitFigure 1-4 BQ79616 Temperature Sampling Circuit

The registers relevant to the OVUVOTUT configuration include:

  1. OVUV threshold configuration registers: OV_THRESH 0x009, UV_THRESH 0x00A.
  2. OTUT threshold configuration registers: OTUT_THRESH 0x00B.
  3. UV disable registers: UV_DISABLE1/2 0x00C/D.
  4. Control register for OVUVOTUT: OVUV_CTRL 0x32C, OTUT_CTRL 0x32D

In Sleep mode, the BQ79616 performs real-time periodic checks for OVUVOTUT, OTCB, and CBDONE. As shown in Figure 1-5, the OV check and UV check are carried out simultaneously. The difference lies in that the VCB_DONE balancing end-of-voltage check is interspersed within the UV check. As shown in Figure 1-6, the OT check and UT check are also conducted alternately, and OTCB balancing overtemperature is interspersed within the OT sequence.

During the diagnostic process, if any fault among OVUVOTUT is monitored, the BQ79616 will transmit a fault tone to the BQ79600, and the BQ79600 reverse-wakes the MCU.

Operation Timing of BQ79616 OVUV/CBDONE in Sleep ModeFigure 1-5 Operation Timing of BQ79616 OVUV/CBDONE in Sleep Mode
Operation Timing of BQ79616 OTUT/OTCB in Sleep ModeFigure 1-6 Operation Timing of BQ79616 OTUT/OTCB in Sleep Mode