Hi all! I have been working on this LED matrix controller project. The aim of the project is to display some rudimentory video on the matrix from the external flash memory, which I want to load in from USB. I wanted to practice some PCB design and embedded software, this is the first PCB I've made with an MCU.

I chose the STM32G0 because it was quite cheap and has 3x SPI which can be driven at 32MHz which is the maximum frequency of the driver chips I chose.

It uses these 2x 16 channel constant current PWM driver chips, using row-multiplexing (Only one row is enabled at once, each driver output controls one column-colour). The drivers are daisy-chained together. The initial goal was to do a 100x100 matrix. However, I wanted to prototype a smaller 10x10 version first to make sure I haven't messed anything up before scaling up.

I want to be able to support the power requirements for the 100x100 in this board, so the change would just be scaling up and not a full redesign. To do this I want to sink 20W using the USB-C PD 9V profile, which means around 6A at 3.3V at the buck converter output.

In terms of review questions:

1. Does the buck converter layout look reasonable? The layout example in the data sheet I saw used this split analogue-digital ground, which I have often read is not good practice, but that lead me to try and lay it out from intuition so I am not sure on it. I am a bit concerned that the component might float around those large pours, but wanted to make sure I could handle a large current.
2. For most of my vias, I chose a 0.45mm via diamater and 0.25mm hole diamater. Is that a bit too small?
3. Is there a more optimal way of laying out all of the traces in the matrix? I am using a lot of vias here which might impact cut up the reference planes, but couldn't think of a better way.
4. Any general design, schematic or layout issues you can see?

Any input is much appreciated, cheers

[Review request] STM32G0 based LED matrix with USB-C PD and external flash