Back Powering the Pi via the GPIO Header?
Looking at designing a HAT which will supply 5V power to the RPi. As a result I'm looking at the notes on back powering  and specifically the link to the back powering diagram. That diagram just show that I need a protection diode in the HAT design, but isn't too specific about the type of diode or any specification for that diode. I'm not an expert but I've seen where people use MOSFET instead of Diodes because of the much reduced voltage drop in the protection circuit. Could that design be used or should a diode, (Schottky?) be used?
Re: Back Powering the Pi via the GPIO Header?
If you want a diode use a Shottky as they have low voltage drop.
You should also add a polyfuse if you power through the GPIO Header.
I recently stopped powering via the GPIO header as I had been for several months, and instead started using PP1 and the underside of pin 6. Using this configuration allows me to bypass the micro USB port, but still have the polyfuse.