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backup SRAM STM32F427 - Vbat

Question asked by Lenora on Oct 20, 2015
Latest reply on Oct 22, 2015 by avi_crak.videocrak
Hello could you please help me with my question about
backup SRAM in STM32F427?

I have design, where I am using voltage regulator for VDD and VDDA - 3V0.
As backup I use batery 3.2V connected to VBAT pin6.
My question is, when I save some data to backup registers, and processor will be without main battery, only backup baterry will be connect to VBAT pin, during long time this backup battery will be fall voltage down.

Do you know on which woltage (minimum), will be this data in SRAM backup registers lost? When VBAT falls below 1,65V data will be lost?

because I try to set VBAT voltabe below 1,65V  (cca 1.0V) and data are still stored in SRAM backup register and data was not losted/cleared.

Data I stored in RTC_BKP_DR0, and when Vbat fall below 1,65V, the data was still in this register. I thinking that under this voltage, will be data from backup SRAM cleared? Is it my assumption corert, or not?