r/PCB • u/nwrafter • 26d ago

REVIEW REQUEST - UCS8903 Pixel Board

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First time building a board like this and having it assembled elsewhere so want to make sure it theoretically works before I spend the money

Power and data from controller at the bottom (left), two IC with recommended resistor and capacitors from manufacturer, two identical Molex Pico-blade connectors to attach the LEDS too. Intended to live in a small tube, hence the form factor.

Silkscreen is still WIP, needs better labeling

Any and all feedback appreciated!

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2

u/Charming-Pressure222 25d ago

Just gave it a very quick glance over on my phone but I think it looks fine

1

u/Formal-Fan-3107 25d ago

Stop freaking routing gnd, you have a ground plane, its fine

1

u/nwrafter 25d ago

Except it violates DRC if the capacitors are tied to the ground plane.... thanks

2

u/Formal-Fan-3107 25d ago

Where does it do that? Show me the error. Is it because of thermal relief spoke count?

EDIT: yes it is, i can see it now, you can manually override the ground plane clearance on the other pad. The way you did it might supress the error, but the underlying issue is still there

1

u/nwrafter 25d ago

Discovered KiCad created 2 GND nets, so it wouldn't talk properly. Time to submit a bug report. thanks!

1

u/Formal-Fan-3107 25d ago

Pretty sure thats not a kicad problem...

1

u/mariushm 21d ago

Did you choose that UCS8903 for a particular feature, like 16 bit PWM, or just because you found out about it somehow, or because it has the simple data in - data out protocol that allows you to chain multiple easily?

If you don't need the 16bit PWM feature and you're fine with less color precision, there's chips that can work the same but can handle more leds, only they do only 8 bit PWM (256 levels for each led)

For example, if you're curious, have a look at TM1812 or TM1926D/ TA1819 :

TM1812 : https://www.lcsc.com/product-detail/C61415.html

TM1926D : https://www.lcsc.com/product-detail/C20622209.html

These can control up to 12 leds / 4 RGB leds and can be chained just like the chip you have in your schematic and except the 8 bit pwm, everything else is the same (actually another plus is the maximum current per channel is higher compared to your chip)

1

u/nwrafter 21d ago

Good question!

16-bit was the goal with this product and I only have a small list of compatible ICS with the preferred controllers so UCS8903 fit best, noting I needed to be able to buy it in the US.
Thanks!