Thank you Dario.
You're absolutely right about efficiency variation vs switching frequency.
In the meantime I would like to update this thread with the new schematics and the board layout.
In this new revision is the switching power supply and the UEXT connector. This will not be populated but it will be available for users that like this type of expansion connector.
The two I2C pull-up resistors will be soldered on but left unconnected from the 3v3 through the SJ2 placed on the back side. I'm thinking that probably the best solution would be to have a SJ for each resistor instead of a single SJ2 in series with the 3.3V. This will prevents a series resitor connections between SCL and SDA lines when UEXT is not used. I'll do it.
The PD5 line is used as slave select in the SPI related part of UEXT connector. This connector receives, as required by the UEXT documentation, the 3.3V generated by IC6.
Lastly, the three relays and related LEDs are directly connected to the Vin.
I'm planning to have a new set of prototypes in next three weeks.
Thank you.
Marco Signorini.
