RTC backup problem with SB45 on nucleo board

Hello,

I was trying to use RTC battery backup on a nucleo F446RET6.

The problem was that the battery (CR2032) connected to VBAT tries (and can't) to power all the board.

Looking to schematic diagram, I see that VBAT pin is connected to VDD thru SB45.

Removing SB45 seems that all is working fine.

Is there a reason for SB45 is there?

Thanks

This topic has been closed for replies.

Best answer by waclawek.jan

While there is no battery (or any other separate power supply) connected to VBAT, it is recommended to have VBAT connected to VDD.

JW

Super User

While there is no battery (or any other separate power supply) connected to VBAT, it is recommended to have VBAT connected to VDD.

JW

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