First PCBs Arrived!

Solar LiPo Charger and 3.3V Buck Regulator PCBs

Solar LiPo Charger and 3.3V Buck Regulator PCBs

The proto PCBs arrived from OSHPark for my Solar LiPo Charger and 3.3V Buck Regulator board! This board is based on the newly released bq25570 IC from Texas Instruments. This powerful little chip combines an ultra low power energy harvester with a boost charger and a nano-powered buck converter. What is all of that good for? Well, powering an MSP430 microcontroller from a solar cell with a small Lithium Polymer battery for backup, of course!

I ordered a Kapton stencil from Ohararp.com since the bq25570 comes in a very fine pitch QFN package. Squeegeeing the solder paste onto the board and then reflowing the solder in an electric skillet worked like a charm.

Kapton stencil

Kapton stencil

After squeegeeing the solder paste through the stencil onto the board.

After squeegeeing the solder paste through the stencil onto the board.

Here’s a photo of the finished board. Note that there are wires directly soldered onto the board instead of the planned JST 2mm connectors. Unfortunately the Eagle PCB library from SparkFun that I used for the footprint was wrong; the holes were too narrow for the pins. Oh well. I guess that will have to be fixed in Rev. B.

Assembled PCB

Assembled PCB

Up next… debugging and characterizing performance with a real solar cell / LiPoly battery / microcontroller circuit. Stay tuned! :)