CE-351 Microcontrollers, 2022 Spring
Power Supply
Name: Mychael Garcia
Email: mhgarcia@fortlewis.edu

Materials:
Power Supply Design:

For this project, we were tasked with creating/updating a 5V and 3.3V power supply. We were creating 4 output channels that could be chosen from; 5V 1A, 5V 3A, 3.3V 1A, and 3.3V 3A.

1A designs:
For the first task, we need to create a 3.3V and 5V design with a 1A current rating. This simple circuit was based off of what is included in the Arduino developer kit.
arduino parduino sch

Using the schematic we reproduce this on our board but with a slightly different layout. The reproduced version can be seen below:
1A


3A design:
After building the 1A designs we created a 3A design. This was done using Texas Instruments LM2596 and schematic builder. Using their schematic design tool we were given a list of needed components, comparing these to ones provided in the lab we had to create our own Eagle reference parts and electrical connections.

The LM2596 can be seen below:
lm2596

Our rebuilt 5V 3A design can be seen below
5V 3.3A

The same process was then used for designing the 3.3V 3A design
3.3V 3A

Connections and Power Output:
After devolving how were going to get the four output options. We need to develop a way to output this to the breadboard and have the option to select which power option we want to use. For connecting to the breadboard were going to use 2 sets of mail headers to connect to each side’s "power" rails (Red outline). In addition, I added a set of female headers that don’t connect to the breadboard and can have a direct connect using male cables (Blue outline).
output headers

Power output selection:
The next step is to devolve a way that each rail can have its own power requirements and that we can select which one we need to use. This was done by adding 8 switches, 4 for each side, 1 for each power option.
switches

Final Layout and Manufacturing:
The final step was to lay out all the components onto a board and design a PCB that can wire all of the connections for us. My final design can be seen below:
designlayout

PCB:
Receiving the PCB I verified some of the major connections and there were no issues.

PCB

Soldering components:
After testing the PCB we soldered all the components on. the hardest parts to solder were the Caps and the LED, the connections for the caps are on the underside so it’s a little difficult to heat the solder up and then place the cap on before it cools. The LED is small enough that’s it’s hard to see the small green bands on it to symbolize the cathode (negative) side.

Soldering 


Conclusion:
Overall this was a very useful and practical project that can be uses in everyday life. For many Arduino projects the included power supply and built in one on many Arduino boards is not enough. Thats where this comes in with its maximum supply current being 3A it should be able to power all accessories.
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