Power Supply Circuit for MCUs
The goal of this lab was to create a general purpose PCB that converts 6V -
12V DC to 5V and 3.3V DC at 1A or 3A. This PCB should be ablke to produce stable DC voltages. This project mostly
followed this tutorial by Dr. Li
Altium Designer was used to create the
schematic and layout components to create a circuit board. This was
chosen over Eagle PCB for the sole reason of using this lab as an
opertuinity to gain experiance with a new piece of software.
This design uses a 6 x 2 pin array (J1)
for power selection where alternating shorts selects either 1A or 3A.
1117 voltage regulators (U1, U2) are used for 1A power, while LM2596
DC-DC converters (U4, U5) are used for 3A power.
Parts where laid out roughly in 5 sections: I/O, 5V 1A, 3.3V
1A, 5V 3A, and 3.3V 3A. Trace width was set to 40mil and routed by hand.
While Altium has more support for images than Eagle PCB, it
seems to only support rasterized images. Within the editor it doesn’t look too
good due to the pixel density being low compared to the close zoom. This will
hopefully look more professional when actually manufactured and the image is
only about an inch tall.
Generating Gerber files
Altium generates more files than necessary to manufacture a
PCB and some of them can cause errors, specifically with using PCBWay, the
wrong file was used as the board outline resulting in misshapen or
missing boards. This was fixed by removing some unnecessary files. The list of files
I ended up with was as follows:
Here, PCB1.GKO defines the board shape.
These gerber files where checked with PCBWay’s online viewer
for errors before sending the files off for fabrication.
10 units arrived form PCBWay. A single
board was assembled. during assembly some issues where noticed. The
pads for 4.7µF, 33µF and the barrel jack where too small which made
soldering very difficult. This however posed no issue to the board’s
functionality. The bottom silkscreen also visually suffers from the
relatively low resolution as the individual pixels are clearly visible.
|PCB with Components
The following shows the PCBs 3.3V output (yellow) and 5V output (blue) at both the 1A and 3A confiurations.
This PCB generates 3.3V and 5V power at both 1A and 3A as desired. DRC runs throwing showing no errors. View the DRC report here
I think Altium Designer, while less intuitive than Eagle PCB, appears to be more
feature rich and versatile piece of software. For future designs I should look
more into manufacturing export settings, image imports, as well as review the built in component libraries before using.