CE351 Fall 2020
Homework 1
Name: KeNeda Randall
Email: kcrandall@fortlewis.edu

PCB Design

Introduction

A power supply circuit was created for an MCU at 5 V and 3.3 V. The assumption is that AC 110 V is available and a AC-DC adaptor will be used to provide a relatively high DC voltage to the PCB.

Materials and Methods

The project requires the Autodesk Eagle software and followes the design tutorials provided for the course. First a new library was created for storing self created packages. After opening a new project folder the required devices (capacitors, inductors, voltage regulators, and diodes) were created and added to the new library. The devices were assembled in a new schematic and checked for errors. Final modification such as mouting holes, wires, and copper were added to the final product and a check for errors was again completed. Once the PCB design was finished, the drill and gerber files were extracted and submitted to an online PCB viewer for final inspection, then submitted for purchase.

Results

A new library in Eagle for storing self-created packages.


A folder was stored under the projects folder for holding the PCB design files.



Next a symbol for the LM2596 voltage regulator was designed and stored in the self created library in Eagle. This is one of a few devices that was created in my personal library or modified using the sparkfun libraries in Eagle.



An image of the accompanying footprint for the LM2596 voltage regulator.



All parts were added to a new schematic and assembled, as shown, in the final schematic below.



5mm (diameter) mounting holes were added and wires autorouted. Once job was completed a copper pour was added, by way of ratsnest, to the top (red) and bottom (blue) of the board.



The drill files were compiled with the gerber files and submitted to an online viewer where a final inspection was completed. Below is the resulting image of the coppertop only.



An image of the coppertop and soldermask.



An image of the coppertop, soldermask, and silkscreen.





Soldering and PCB Test

Each component was soldered to the board. A final test was conducted using the highlighted pins to check for functionality.





PCB test output voltage at 5V, 1A.


PCB test output voltage at 3.3V, 1 A.


PCB test output voltage at 5V, 3A.


PCB test output voltage at 3.3V, 3A.



Conclusion
The gerber files to the final design of the PCB were submitted for fabrication to PCBway.com and a week later a physical PCB was received. Each component identified in the PCB design was soldered onto the board using solder paste and a soldering rod. Once all components were attached a test of the output voltage was conducted for the 5V_3.3V_1A_IN pin, 5V_3A_IN pin, and the 3.3V_3A_IN pin (highlighted in the photo above). Final results indicate a functioning PCB since testing each pin produced the expected output voltage reading. Recommended design alterations include reducing the physical size of the board to both reduce cost and space occupancy.