I would like to make a automatic switching of source for my buck converter when the input voltage is below 5v.
In the very simplified circuit image above as you can see the input voltage can be 3.3V or 6V or 8.4V. The buck converter that outputs 3.3V has a minimum input voltage of 4.5V, this is a problem when the source voltage is 3.3V. So instead if the source voltage is 3.3V (or anything below 4.5V) it must get its power from the buck-boost converter that constantly output 7.5V.
How do i create a switch that switches when the voltage is at a certain threshold. Also it would be nice to create a hysteresis to prevent it from going crazy