Can I use SMPS in microcontroller for AC-DC converter?

[KKIM.6]

The STM32WB55 microcontroller have SMPS internally.

Can I use it to convert AC power to DC power for the microcontroller?

If possible, I want to supply RF inductive charging power directly to the microcontroller.

[KKIM.6]

After reading manual, I understood the SMPS is only for power efficiency when Vdd is high enough than 3.3 V. Unfortunately, I think it cannot be used for AC-DC converter...

[Andrew Neil]

"After reading manual, I understood"

Yes, that is why manufacturers provide datasheet to tell you these things!

Absolute Maximum limits:

 

[KKIM.6]

No. My question is whether SMPS in microcontroller can be used for AD-DC converter but, it is not in manual.

[Andrew Neil]

Go on.

It clearly tells you that the minimum input is, essentially, zero and the maximum is 4V; so that can't possibly be AC - can it?

https://www.circuitbasics.com/what-is-alternating-current/

[KKIM.6]

Yes. It would be true. However, if there is a diode, I can apply half-wave but still, information is insufficient because I don't know that the SMPS has a bridge rectifier inside.

[Andrew Neil · Accepted solution]

it tells you that the minimum input is, essentially, zero - so you can't apply AC.

Therefore you would need to provide any rectification externally.

The datasheet also tells you that it is a step-down SMPS, so it wouldn't be able to cope with a rectified AC supply - which drops to zero once (half-wave) or twice (full-wave) per cycle.