I'm trying to do a simple, low power, low cost power "switch" for a custom board (I know, it will be complicated).
The device will be powered by default by a coin cell battery (3V3 and lower) and can also be powered by USB (5V). I will use a boost converter (TPS61291) for the battery, it will allow a constant 3V3, with a bypass for sleep mode controlled by a MCU.
This is a part of the power rails I designed:
The battery is protected by the schottky diode (some nA can flow into it, but it is accepted by the manufacturer)
If the VUSB is not present, the diode D2 will avoid reverse current in USB connector. D4 is protecting the LDO itself from the reverse current by bypassing it.
The boost bypass will be activated by the MCU when it is in active or when USB is plugged.
Do you think it will work correctly?