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Associate
November 23, 2025
Question

STM32U5A5 Power Sequence

Hi All,

There is any problem if VBAT powered before VDD? (VBAT is another supply that feeds from Battery with LDO ) 

I deep dive all the datasheet and didn't find any reminder about it.

1 reply

TDK
November 23, 2025

No, there is no issue with VBAT present before VDD.

The whole reason for VBAT is to have a battery backup for certain things on the chip like RTC when power is otherwise not available. If VDD was required for VBAT, it would prevent that capability.

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