Good afternoon,
I have a stm32l432kc microcontroller on a custom board with two voltage supplies:
1) A LiPo battery where I use a regulator to supply 3.3v to power everything and
2) A coin cell battery to only provide power to the RTC within the micro.
On the datasheet it states that:
"The RTC and the 32 backup registers are supplied through a switch that takes power from the VDD supply."
The regulator is providing power to this VDD pin. The switching of supplies isn't a problem as I can achieve that through some diodes. My problem is that the coin cell should exclusively be supplying the RTC within the microcontroller to maintain the time, and at no point should the coin cell be supplying current that contributes to the sleep mode.
Is this possible without a dedicated VBAT pin?
