RAM retention fail when changing the supply voltage

[Turnaev]

Hello!

I have next problem. When switching from backup power to main power, the controller loses data in RAM. If the backup voltage is below about 2.4V, then it is possible to observe saturation of the stabilizer1.12V (DEC1), which often leads to data loss in RAM. At the same time, the controller sleeps in WFE mode, used SystemON mode. All capacitors as described in hardware recomendations. VCC not fall below 2V.

How I can eliminate this trouble?

[Turbo J]

Might be power-on reset because of the increase in voltage on the VCC rail:

"A step increase in supply voltage of 300 mV or more, with rise time of 300 ms or less, within the valid supply range, may result in a system reset." (quoted from the Power-On Reset chapter in the PS).

[Turnaev]

Yes it could be. But why is the contents of RAM damaged.

I use uninitialized sections of memory for my purposes, and they get corrupted in doing so.

[Kenneth]

Hi,

If you have a step up in supply voltage of >300mV in <300ms, then you may experience the internal power on reset circuit to trigger yes. In such case you can find the following description on how the chip will behave:
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/power.html?cp=3_1_0_17_7#unique_832471788

'x' means: "Note: The RAM is never reset, but depending on reset source, RAM content may be corrupted."

Best regards,
Kenneth

[Turnaev]

It is very bad... Ok 

Thanks for the help!