Should I add a decoupling capacitor to my RGB 16x32 LED matrix powered directly via the 5V pin?

When I display a spectrogram, the current load is fluctuating quickly in the 100-250 mA range (on average, the full range is 50-300 mA).

If yes, which capacitor should I pick for this purpose?

I have 0.01 μF, 0.1 μF ceramic and 1 μF, 2.2 μF, 4.7 μF, 10 μF, 100 μF electrolytic caps.

EDIT: I'm also interested to know about this WS2812B LED strip i've connected to the 5 V pin to another Arduino.

After reducing the brightness it has similar current consumption and fluctuation of the LED matrix.

In this tutorial they suggest to add a 1000 μF cap, but in my case the currents are much smaller.

1 Answer 1


No, there is no need. The matrix already has plenty of decoupling on it, including a large electrolytic for the incoming power and a small ceramic on each of the chips.

  • Possibly. The LEDs are "active" in that they have drive circuits in them. They should have decoupling with the LEDs in the strips. It can be good to provide a large reservoir capacitor for that though (the equivalent of the electrolytic on your matrix).
    – Majenko
    May 23, 2017 at 15:17
  • i've checked the led strip and indeed it has small caps near each WS2812B chip.
    – eadmaster
    May 23, 2017 at 15:30

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