u/ShaunTheMad

I'm trying to design a circuit to select a power input for my CM4002008. It should use VBAT only if the USB is unpowered.

I've set the circuit up to use a p-type MOSFET to let the USB source whenever it's powered. The voltage drop created by D1 should allow the USB to take priority when both are powered, while also preventing backflow.

Based on the FET symbol I think I oriented the FET correctly, but what has me scratching my head is that the Drain of the FET is connected to the USB source, while the source of the FET is connected to the drain, which seems wrong. Am I right in thinking the arrows on the FET symbol indicate the direction of current? It seems like the FET symbol contradicts itself.