23.6.5.3 Brown-Out Detector (BOD33)
The 3.3V Brown-Out Detector (BOD33) is able to monitor either the VDD or the VBAT supply .
The Voltage Monitored bit in the BOD33 Control register (BOD33.VMON) selects which supply is monitored in active and standby mode. In backup mode, BOD33 will always monitor the supply of the backup domain, i.e. either VDD or VBAT.
If VDD is monitored, the BOD33 compares the voltage with the brown-out threshold level. This level is set in the BOD33 Level field in the BOD33 register (BOD33.LEVEL). This level is used in all modes except the backup sleep modes. In backup sleep modes, a different voltage reference is used, which is configured by the BOD33.BKUPLEVEL bits.
When VDD crosses below the brown-out threshold level, the BOD33 can generate either an interrupt, a Reset, or an Automatic Battery Backup Power Switch, depending on the BOD33 Action bit field (BOD33.ACTION).
If VBAT is monitored, the BOD33 compares the voltage with the brown-out threshold level set in the BOD33 Backup Level field in the BOD33 register (BOD33.BKUPLEVEL).
When VBAT crosses below the backup brown-out threshold level, the BOD33 can generate either an interrupt or a Reset.
The BOD33 detection status can be read from the BOD33 Detection bit in the Status register (STATUS.BOD33DET).
At start-up or at Power-On Reset (POR), the BOD33 register values are loaded from the NVM User Row.
References: