Starting from using 12V 1A wall adapter, Power will be supplied to My Raspberry PI through 5V rail. My plan is as follows : 1. Down convert 12V to 5V. 2. The converted voltage will be connected to both 5V rail and VIN for battery charger (LTC4067) 3. When wall adapter is connected, output of 12V to 5V regulator will supply power for RPI directly through 5V rail. 4. When wall adapter is disconnected, stored energy in 4.2 LI-PO battery will be supplied to RPI.
I know that recommended input voltage for RPI is 4.75~5.25 and expect that 4.2V LI-PO battery supplies quite insufficient voltage. My questions are here : a. Is boosting output voltage of LTC4067 to 5V necessary? b. If so, is it okay to just connect the boosted voltage to 5V rail?( in aspect of backward protection)
I'm really really unskilled novice and I don't know much about constructing circuit. I would be appreciated if you answer this question.