Power BeagleBone Black with 3.7V Li-Po, Li-ion


Please excuse me if this exact question has been asked already but I haven’t found anything as of yet.

I am trying to build a mobile phone system and am designing a board to act as an intermediate cape between my beaglebone and this LCD cape:

Being that this is a mock mobile application, I would like to keep the design lightweight and use a small battery. I have a 3.7V 4500mAh Li-ion from an android cellphone that I would like to use.

What I would like to do is:

  • Use the on board TPS65217 along with modified code to provide system power (3V3).
  • Charge the li-ion battery via 65217 when barrel jack is connected.
  • Connect the V_BAT net to power the sim900 module that I’m using.
  • Power LCD cape’
    My question is in a way to interface all this together safely. The missing link in my design is a way to get the SYS_5V needed by the LCD cape. I would only like the 5V rail after the system has booted (MOSFET via GPIO maybe?)

and power it down fully before the system powers down. Maybe I need to RTFM more, but some direction or input would be greatly appreciated. Thank you