LiPow - The USB C LiPo Battery Charger

While searching for a programmable supply to use for the LiPo charger, I discovered the BQ25703A from Texas Instruments. It is a very feature rich part that can charge 1-4s LiPo's from a USB PD based input (5-20V). Which means it is a programmable buck-boost regulator. It also has a max output of 6.35A which is also programmable. The programming interface is I2C.

For supporting components, it will need a 3 MOSFETS that can handle 6.35A, a couple of smaller FETs, an inductor, some capacitors, and a couple of shunt resistors for current measurement.

I have selected the STM32F030F4P6 as the microcontroller for this project. My main search criteria were ARM M0 based, at least one I2C peripheral, ADC with at least 4 channels, availability, and price.

The STM32F030F4P6 fit all the criteria and the price is right. I ruled out the Cypress parts for not having enough IO. Between the Zilog part and the two ST parts, I would rather use ST since I have experience with them. Between the two ST parts, I chose the one with a larger available quantity.