Latest HW modifications after the testing session

A project log for Scorpion 3.0

Multi tool design for the IIIrd world countries

Marius TaciucMarius Taciuc 11/08/2017 at 04:060 Comments

   During the testing sessions, when I was increasing the output power above 30W, sometimes the MCU would reset and I was seeing this in a jam of the chars on the display. I realized that I made a mistake in the design of the layout and that would be routing the power trace too close to the MCU and too close to the 3.3V line. When I calculated the voltage per meter for some traces, I was shown values of almost 5000V/m and clearly this is not so good for my EMC.

   The HW modiffications I did are the following: 

 1. Cut the power trace on the bottom side of the PCB and replaced it with an external shielded cable

2. Replaced the output cap of the LM317 with a 470uF one.

3. Doubled the size of the output filter

4. Placed a 100nF cappacitor in parallel and very close to the MCU

Now it works like a charm and with this firmware, I managed to output a maximum power of 45W out of it. The efficiency is very good and the LM2596 does not heat above 40C, which is a success. Normally, a C1 iteration of the layout should be created after the first series of tests. Stay tuned for more updates and hopefully some test report posts.