Trying to create a switch-over with two p-channel MOSFETS using arduino. I need to switch between 2 sources with a GPIO pin from my arduino. I've looked into ideal diodes such as the LTC4414 and the LTC4415 but its hard to get them with my local supplier and I want to see if this is possible using FETs. I've seen some solutions using just diodes but I am not really interested in the inefficency they introduce.
The purpose is to do a power switchover e.g. source 1 dies, source 2 switches on.
Source 1: 11.4v, 1300mah nimh
Source 2: 12 DC wall adapter
The circuit it powers will sometimes require somwhere between 2-4 amps peak.
Would the following circuit work?? I don't have any p-channel mosfets to test it out (side note: recommendations welcome). I'm trying to keep everything through-hole (yes I know … relic of the past) but I don't have the necessary gear to solder small stuff.
Best Answer
In the circuit you show you will not be able to control M1 or M2 since you have not correctly interfaced the gate voltage relative to your input voltages.
I think what you might be able to copy is the schematic of the Si4700DY (now obsolete but they give a good schematic) http://www.vishay.com/docs/71110/71110.pdf
In this schematic they ideally need VG pulled up to a value equal or greater than either source voltage. In practice you should be able to use two low VF diodes (such as the SB320) and still ensure the FET can be turned off.
You'd end up with something like this: