Hi. I have two switching regulators with 4.5-9V and 9-18V input. I want to put them in parallel in order to make a system that can accept 4.5-18V, where only only one regulator is ever active and the the input voltage stays well away from 9V will never cross it for a given input voltage.
I'm not sure if all I have to do is use the disable pin on the non-functioning regulator to protect the low voltage regulator from higher voltage inputs (the company also won't seem to tell me). The two regulators are from the same series (they share the same datasheet), and just have different input ranges, but I am not sure what physical (not functional) input voltage a device can tolerate.
Also, I am not sure what will happen on the outputs when one regulator is working and the other isn't (will it behave as a sink? unexpected capacitive load?).
Does anyone have any idea? These are buck-boost converters I think (they work on an input that is both higher and lower than the output voltage).