Hi,
We are using the chip PowerSTEP01 in our design. In the datasheet, it is mentioned in the application diagram that the VDDIO pin can be powered from the VREG pin. However, the X-NUCLEO IHM03A1 evaluation board design shows that it is powered externally. Which one is the correct way of doing it? Are there any problems or limitations in powering the VDDIO from the internal regulator?
Best Regards,
Biju
Welcome
There is an internal LDO behind the pin VCCREG, which generates the 3.3V from the voltage at VCCREG, which is fed out at the pin VREG. However, if you want to supply VREG externally with 3.3V, you must connect VCCREG and VREG together and then apply this external voltage there (see data sheet, section 7.19, under fig 15).
It is therefore not a question of one of the two options being more correct, but of application variants.
Does it answer your question?
Regards
/Peter
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