I have a circuit I'm working on that has two power sources, one varies between 40-60V, and the other is 72V. The 72V power source will typically always be on, and the 40-60V source may be on or off.
I am trying to make a circuit that will prioritize the 40-60V source as the main source, if it is switched off, the 72V source takes over automatically.
I've found chips like the LTC4355 but can't handle the higher voltages. I've looked into something simple using a couple op-amp comparators like in the model below but pretty sure I need to use p-mosfet's since the switch needs to be on the high side. If I have to use p-mosfet's then the opamp voltages need to get much higher to drive the mosfet which I'm not sure how to do (mosfet gate driver IC?)
Looking for advice, direction, or anything to help me figure this out. I'm not an EE, obviously. Thanks.
EDIT: Operating range for the load right now is 30-60V. I cannot have a loss of power. The load can be up to 12A at 48V.
ANOTHER EDIT: Redone the whole circuit with the below circuit.. Still can't quite get it to switch but I think this circuit makes a little more sense. Trying to run spice sims on it but having trouble with spice models of the parts right now..
EDIT3: So after trying various circuits, I came across this and High Voltage MOSFET Switching Circuits for H-Bridge Motor Controls and used the same through process for this circuit. Found parts that seem to work and ran it through Pspice. Seems like it works. Anyone see any issue with this circuit (other than some decent cooling on the mosfet)? I attached the results from Pspice as well