Hey guys, this is my first post on PJRC. Loving the Teensy board! So much so that I want to try creating a PCB with it.

I want to have Vin be powered by a battery connection - a 3.7V LiPo. Then I would like to be able to plug in the USB such that it charges the battery. Also I want to make sure everything is getting the right voltage/current/power.

I don't know very much about battery electronics. Here is what I am initially thinking:

- Use this charger as a starting point: https://www.sparkfun.com/products/10217
- For the purposes of my PCB schematic, replace the USB connector with a simple wire that connects to the output power, the 3.3V pin of the Teensy (can 3.3V even charge the battery like this?)
- This is super hard / frustrating to describe. Here's a schematic with annotations of what I'm thinking:


My other big concern: the Teensy 3.0 voltage input (which I take to mean Vin) can only work with 3.3V. If my battery is 3.7V LiPo, is there a simple step-down DC-DC converter I can drop into my schematic?

In my schematic I found an Eagle library from here:

I understand this is a rather involved question and I'm still learning circuits / PCB design, so big thanks in advance! Bonus points if anyone shares or can quickly whip up a schematic I can use to do this