7.4.1 VDDBU Power Architecture

The backup power switch aims to optimize power consumption from the VDDBU source by switching the supply of the backup digital part (backup registers and memories, plus the 64 kHz RC oscillator) to VDDANA.

When enabled, the backup power source can be automatically switched to VDDANA, which reduces power consumption on VDDBU. Then, VDDBU powers the pads, VDDBU POR, and the 32 kHz crystal. On secure products, SAMA5D23 and SAMA5D28, VDDBU also powers the temperature sensor and the backup supply monitor.

The power source (VDDANA or VDDBU) can be selected manually or can be set to work automatically by programming an SFRBU register (refer to SFRBU_PSWBUCTRL in the Special Function Registers Backup (SFRBU) section).