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Update: Based on feedback I have received, I have added some capacitors. I added a 470uF electrolytic capacitor at the start of the 5V and GND line, a 0.1uF ceramic capacitor every 5 LEDs, and a 10uF capacitor about every 10 LEDs. enter image description here enter image description here enter image description here

Original Post: This post is related to my previous post: PCB Design Feedback. This is the LED array that I designed for the project, that I plan on using.

Below is the schematic, it consists of 57 WS2812E-V5 LEDs. I know that for a lot of these types of LEDs, capacitors are typically used. The datasheet for this LED is in a different language, but there’s a schematic and it doesn’t show capacitors. https://datasheet.lcsc.com/lcsc/2111171930_Worldsemi-WS2812E-V5_C2920042.pdf

I found a datasheet in English for WS2812B-V5 which seems to be similar to what I’m using (WS2812E-V5), and the datasheet says “The peripheral circuit don’t need to add filter capacitor” http://www.peace-corp.co.jp/data/WS2812B-V5_V1.0_EN.pdf

I could be wrong, but it seems that for these LEDs, you don’t need capacitors. They may already be built in, I’m not too sure.

enter image description here

From the schematic I made the PCB design below. There is a ground pour on the back (in blue) and I am using vias to connect the ground of each LED to the ground layer. I am also using a 5V pour on the front (in red). If I could get some feedback on the design and if you think it'd work that’d be great. Thank you!

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    \$\begingroup\$ Many datasheets do not specify capacitors since their presence is so ubiquitous as to be implied. If you are switching a relatively large load at high frequency, then bulk capacitance will almost always help. Also, I don't read Chinese but there could very well be a note about that in the datasheet. \$\endgroup\$ Commented Apr 24, 2023 at 21:31
  • \$\begingroup\$ Also, that 470 ohm resistor in series with the megaohms // few pF of the CMOS input gate isn't going to do much. Did you mean to put it on the opposite end of the line? \$\endgroup\$ Commented Apr 24, 2023 at 21:37
  • \$\begingroup\$ Look at your chip and see if the capacitor is included on package. Some include it, some do not, so if you aren't sure what you bought you can double check. If it's not there you have to put it on PCB. Regardless you should at least add some bulk capacitance to the board with that many switching PWM lights. \$\endgroup\$ Commented Apr 25, 2023 at 0:04
  • \$\begingroup\$ Not what you asked, but which pin on the LED is the thermal connection? If you are going to hand solder the LEDs, the thermal reliefs make sense but for hot air soldering, I would remove them to maximize the thermal coupling to your plane. \$\endgroup\$ Commented Apr 25, 2023 at 8:25
  • \$\begingroup\$ @winny What's a thermal connection, I don't think the LED has one? I plan on ordering the assembled board from JLCPCB, not hand soldering. And what part is considered thermal relief because I didn't intentionally add any. \$\endgroup\$ Commented Apr 25, 2023 at 12:14

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Based on fairly flimsy evidence (images taken from world-semi.com) , would say the WS2812E-V5 does not have a built-in capacitor, whereas some other ones do:

WS2812E-V5

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WS2813C

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There is no mention I see of capacitors in the WS2812E-V5 Chinese datasheet.

I suggest adding pads for at least a certain number of capacitors, perhaps 1uF for every 5 LEDs on the bottom of the board and a couple larger ones on the top. If you don't need the ones on the bottom, nothing is lost.

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  • \$\begingroup\$ What values would you suggest for the larger ones, and should they be ceramic or electrolytic capacitors? \$\endgroup\$ Commented Apr 25, 2023 at 2:40
  • \$\begingroup\$ Maybe 10uF X7R or X5R ceramics 0805 or 1206. \$\endgroup\$ Commented Apr 25, 2023 at 2:47
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Question about capacitor. I looked for a PCB design in production and found this picture. enter image description here

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