SLUSCU0I March 2018 – September 2020 BQ77915
To improve reliability, the device has a built-in CRC check for all the factory-programmable configurations, such as the thresholds and delay time settings. When the device is set up in the factory, a corresponding CRC value is also programmed to the memory. During normal operation, the device compares the configuration setting against the programmed CRC periodically. A CRC error will reset the digital circuitry and increment the CRC fault counter. The digital reset forces the device to reload the configuration as an attempt to correct the configurations. A correct CRC check reduces the CRC fault counter. Three CRC fault counts will turn off both the CHG and DSG drivers. If FETs are opened due to a CRC error, only a POR can recover the FET state and reset the CRC fault.
In addition to the CRC check, the device also has built-in-self-test (BIST) on the comparators. The BIST runs in a scheduler, and each comparator is checked for a period of time. If a fault is detected for the entire check period, the particular comparator is considered at fault, and the CHG and DSG FETs are turned off. The BIST continues to run by the scheduler even if a BIST fault is detected. If the next BIST result is good, the FET driver resumes normal operation.
The CRC check and BIST check do not affect the normal operation of the device. However, there is not specific indication when a CRC or BIST error is detected besides turning off the CHG and DSG drivers. If there is no voltage, current, or temperature fault condition present, but CHG and DSG drivers remain off, it is possible either CRC or BIST error is detected. Users can POR the device to reset the device.