I want to design a circuit that can handle the following three scenarios:
Both an input source and an load are present. The load will be powered from the input source. When the input source can deliver enough current, the backup battery will be charged as well, but this is not an priority.
An input source is present, however no load is present. The backup battery will be charged.
No input source is present. The load will be fed from the backup battery.
The input voltage will be in the range of 3 -12V, the output voltage has to be 5V (USB). A single cell backup battery will be present. The output current has to be at max 2A, the input current will be at least 100mA and at max 3.
Is there an IC that can handle all of this? Or would I need both an battery charger and a buckboost converter in front of it?
Thank you for your time.