19.6.5.3 3.3V Brown-Out Detector (BOD33)

The 3.3V Brown-Out Detector (BOD33) is able to monitor either the VDD or the VBAT supply and compares the voltage with the brown-out threshold levels.

In all mode except battery backup mode, the BOD33 compares the VDD voltage with the brown-out threshold level. This level is set in the BOD33 Level field in the BOD33 register (BOD33.LEVEL). When VDD crosses below the brown-out threshold level, the BOD33 can generate either an interrupt,or a Reset, or an Automatic Battery Backup Power Switch, depending on the BOD33 Action bit field (BOD33.ACTION).

In battery backup mode, the BOD33 monitors both the VBAT and VDD supplies alternatively. When VBAT crosses below the backup brown-out threshold level (BOD33.VBATLEVEL), the BOD33 generates a Power Supply Reset. When VDD crosses above the brown-out threshold level (BOD33.LEVEL), the device will leave battery backup mode and will wakeup from backup mode if the BBPS.WAKEEN bit is set.

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.