Finally Testing the new Board

A project log for Solar Energy Generator

A solar energy system up to 500W in power for use with lithium batteries.

nathaniel-verleeNathaniel VerLee 12/29/2014 at 17:260 Comments

After assembling one of the three boards I had fabricated, I have finally gotten a chance to start testing. A new job and move process has put a lot of my side projects on hold and I am finally getting the chance to return to this project. The first step was to verify that the 1.8, 3.3, 5 and 12V rails were working properly. I made a silly mistake with the 12V boost converter: I entered the schematic as if it was a buck. It was an easy enough rework to do with a piece of kapton and some wires. I also made the easy mistake of getting the wrong IC package for the TPS54360 that I am using for the 5V buck converter. After I got all the rails up and working I moved on to connecting them to their respective loads and discovered a lovely dead short on the 3.3V rail (on the digital side). The 3.3V supply powers two rails - an analog and a digital one. Each is isolated from the other via a Pi filter, which is a kind of cap-ferrite-cap arrangement designed to prevent noise created by pulsating digital currents from the micro from propagating into the analog instrumentation circuits. It was the digital rail that appeared to be shorted, and after removing the micro this proved to be the case. After thoroughly inspecting this rail there are no visible mistakes in the layout files, and since most of these traces are in one of the midlayers I can only assume that they became shorted because I got too close to a manufacturing tolerance. In any case it was easy enough to rework, and the next steps will be to start getting code on the micro and get the buck stages up and running. From there I will be tweaking the voltage and current measurement circuits (they probably need a low pass with a steeper roll off) and trying to write a basic 3 stage battery charging algorithm.