SLUSFQ1A December 2024 – December 2024 BQ41Z90
ADVANCE INFORMATION
Refer to the PDF data sheet for device specific package drawings
The BQ41Z90 device includes two pins (CFETOFF and DFETOFF) which can be used to disable the protection FET drivers quickly, without going through the host serial communications interface. When the selected pin is asserted, the device disables the respective protection FET. Both the CFETOFF and DFETOFF pins can be used for other functions if the FET turnoff feature is not required.
The FET drivers in BQ41Z90 device can be controlled in a couple of different manner, depending on customer requirements:
Fully autonomous mode: The BQ41Z90 device can detect protection faults and autonomously disable the FETs, monitor for a recovery condition, and autonomously re-enable the FETs, without requiring any host processor involvement.
Partially autonomous: The host can assert the CFETOFF or DFETOFF pins to keep the FETs off. As long as these pins are asserted, the FETs are blocked from being re-enabled. When these pins are de-asserted, BQ41Z90 will re-enable the FETs if nothing is blocking them being re-enabled (such as fault conditions still present, or the CFETOFF or DFETOFF pins are asserted).
Manual mode: The BQ41Z90 device can detect protection faults and provide an interrupt to a host processor over the ALERT pin. The host processor can read the status information of the fault over the communication bus (if desired) and can force the CHG or DSG FETs off by driving the CFETOFF or DFETOFF pins from the host processor.
The host inputs (CFETOFF/DFETOFF) when selected are “OR-ed” with the other reasons for BQ41Z90 to turn off FETs, such as upon detecting SCD/OCC/OCD conditions which requires various FETs (CHG/DSG/PCHG/PDSG) to be turned off.