I'm working on a project which involves setting the clock on a Pi Pico over USB and then seamlessly switching over to battery power when the USB connection is removed. How to accomplish this is documented in the PDF for the Pi Pico, with the following diagram:
Try as I might, I can't find or figure out what Schottky diode to use. I'm thinking that the battery supply voltage will be around 3 - 4.8V (3xAAA or 4xAAA NiMh cells). The maths involved in calculating which diode is just a bit beyond me.
PDF source, section 4.5.