Question
What MCUs have backup SRAM maintained by VBAT?
STM32F407VG has 4kB of backup SRAM that's preserved when VDD is removed if VBAT is present. A few other MCUs in the STM32F40x line have that feature too.
Do any MCUs outside of the STM32F40x line have SRAM that's preserved with VBAT? Is there a way to search for this feature in the MCU product finder?