I'm currently developing a project, where I have to design SMPS using a digital controller.
The system is supposed to supply the microcontroller during operation. But the microcontroller still needs a supply to start up the system. I was told there were methods to supply the microcontroller during start up, which later gets turned off when the SMPS is fully operational.
Right now I am having a hard time finding any sources or applications notes that describes these methods.
The microcontroller used is STM32l4R5-p with an input range of 1.71 to 3.6 V_DD when using internal LDO. But the whole SMPS project has an input range of 115 to 230V RMS ±10%, which I know is a bit of a challenge.