Hi
In MAX1747 datasheet, there is the montage in the picture above, everything is clear with the values and everything, only those diodes I don't understand what is their role, also they put them without any information about them in the datasheet so I don't know how to choose them, anyone has an idea about that?
Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX1747.pdf

 

You just didn't read far enough.
They are mentioned on page 12 of the data sheet (Rectifier Diodes).

 

Thank you

 

The diodes with the capacitors form a voltage multiplier ( 3 × the input voltage ) The voltage is controlled with the feedback circuits inside the IC.