CE351 Lab 2020 Fall
Power Supply and DC Regulators on a PCB for MCUs
Name: Audra Benally
Email: albenally1@fortlewis.edu

1. Title: Power Supply and DC Regulators on a PCB for MCUs

2. Introduction:
    In this lab, a functioning power supply board will be designed to use with future MCUs. The program being used will be Eagle PCB. Personal libraries and devices will also be made to accomodate for parts not included in the SparkFun library. Gerber files will then be made and sent to PCBWay for fabrication. Once the boards came in, the components were soldered and assembled. The resulting board was tested for accuracy.

3. Materials and Methods:
       Materials:
          - Computer with Eagle PCB
          - Step by step tutorials from yilectronics.com
          - Calculator
          - Soldering iron
          - Multimeter
          - Flux
          - Solder
          - Board components: capacitors, inductors, diodes, chips, etc...

       Methods:
    For this lab, a step by step tutorial was followed to create a power supply board. The first circuit was constructed with devices from the SparkFun library. The second and third circuits needed specific devices that were not included in the given libraries. Several capacitors, inductors, a diode, and two 5-pin LM2596 devices were created from the datasheets of each specific component. Once the parts were built, the last two circuits were constructed. The completed schematic of the circuit board can be seen in figure 1. The schematic was then checked for potential errors with an ERC check. Once all the errors were cleared, the board was constructed and the physical connections were made. The board was then checked for errors with a DRC check. Figure 2 shows the completed board layout. Figure 3 shows the DRC check results. Once the board came in from production, the components were soldered according to the schematic. The board was then tested for accuracy; The results can be seen in Figures 6 - 9.

4. Results:

   
             Figure 1. The completed schematic with 0 ERC Errors.

   
             Figure 2. Finished board.

   
             Figure 3. 0 DRC errors in board layout.

   
             Figure 4. Completed PCB.

   
             Figure 5. The power in pins. On the left: 3.3V 3A IN. Middle: 5V 3A IN. Right: 5V 3.3V 1A IN.

   
             Figure 6. The far left 3.3V 3A in pin is shorted to the power input and the ouput shows 3.271V.

   
             Figure 7. The middle 5V 3A in pin is connected to power and the ouput correctly reads 5.004V.

   
             Figure 8. The right 5V 3.3V 1A in pin is connected to power and the 5V output is probed and shows 5.004V out.

   
             Figure 9. The right 5V 3.3V 1A in pin is connected to power and the 3.3V ouput is probed and shows 3.300 V.

5. Discussion
    This introduction to Eagle PCB was incredibly informative. The tutorials provided just enough frustration to drill the experience into my head. The ERC and DRC checks were very undescriptive so playing with the different components, including the library devices, was particularly educational. Redoing the components that I had done incorrectly the first time was enlightening. The videos were very easy to follow. The wiring of the physical components of the board was my favorite part and especially enjoyable. This was my first time soldering anything. It was rocky in the beginning; I completely missed a pin for my LM2596 3.3V chip and I put a couple diodes in backwards. After much debugging, the circuit board was functioning correctly with the results shown in figures 6 - 9. I really enjoyed this entire lab. The product of my hard work will be well deserved and properly cherished.