For a project I'm working on, I need to run a motor for a few seconds (somewhat rarely). The motor requires 24V@1A. The rest of the circuitry runs on 3.3V@300mA. My general thought is to use a 3.7V LiPo battery to act as a "current booster" (since it can discharge at a much higher rate than it charges) and add a buck regulator to get my 3.3V. A 5V@1A USB power supply would both charge the battery and power the 3.3V regulator.
That circuit is understood, using a LiPo charger with power-path circuitry to allow the buck regulator to run off the USB input or the battery when no USB power is available. And as a bonus, this also creates a built-in "UPS" that will run off the battery for some time if the USB fails or is disconnected.
But the second part (and the main reason for the battery) is the 24V requirement. This is easily done using a boost regulator to produce the 24V@1A from the LiPo (there are plenty of "high discharge" LiPo cells that will easily provide the necessary current). But I'm not sure how to use the LiPo as the power source without disconnecting the USB power and running only off the LiPo while the motor is running. This actually works, but it seems like there should be a more elegant solution. It's a different problem than the 3.3V buck regulator, since either the USB or the LiPo can provide the power, but with the 24V boost regulator, only the LiPo can provide the power.
I've done a fair bit of online research, but I haven't found anything that really covers this use-case, so maybe I'm not searching for the right thing. Any pointers?