Each single 20mm RGB LED pixel can draw up to 60mA from a 5V supply. That means a strand of 20 can use up to 1.2 Amps. That’s a peak rate, which assumes that all the LEDs are on at full brightness. If most of the LEDs are kept dim or off (as when animating patterns), the average power usage can be 1/3 this or less.
We suggest a nice switching supply for driving LED pixels:
Note the embossed polarity markings. Connect the red wire to the + terminal and the blue wire to the - terminal.
- When linking multiple strands together, power should be split and applied to each strand. If you try to power too many LEDs from just one end of the strand, they’ll start to “brown out” the further they are from the power supply.
- Strands can be powered from either end — “input” and “output” doesn’t apply to power, only the data signals from the microcontroller.
- If the 10 Amp power supply isn’t large enough for your project, a slightly modified ATX computer power supply can provide 30 Amps to power upwards of 500 pixels!
- Generally speaking, you should not try to power an LED strand from the Arduino’s 5V line. This is okay if just a few pixels are lit, but is not adequate for driving a full strand.
- For a standalone application (not USB connected to a computer), you can power the Arduino from the same regulated 5V supply as the LEDs — connect to the 5V pin on the Arduino, not Vin, and don’t use the DC jack on the Arduino.
- Remember to insulate or trim any unused, exposed power wires!