WS2812 datasheet(43/98 Pages) RASPBERRY-PI

43 / 98 page

For most non-portable “desktop” projects, a 5V DC

switching power supply (http://adafru.it/276) is ideal. This

small 2 Amp supply is good for a a meter or so of

NeoPixel strip. We’ll explain larger projects in a moment.

Be extremely cautious with bench power supplies.

Some — even reputable, well-regarded brands — can

produce a large voltage spike when initially switched

on, instantly destroying your NeoPixels!

If you use a bench supply, do not connect NeoPixels

directly. Turn on the power supply first, let the voltage

stabilize,

then connect the pixels (GND first).

Estimating Power Requirements

Each individual NeoPixel draws up to 60 milliamps at maximum brightness white (red + green + blue). In actual use

though, it’s rare for all pixels to be turned on that way. When mixing colors and displaying animations, the current draw

will be much less. It’s impossible to estimate a single number for all circumstances, but we’ve been using 1/3 this (20

mA per pixel) as a gross rule of thumb with no ill effects. But if you know for a fact that you need every pixel on at

maximum brightness, use the full 60 mA figure.

To estimate power supply needs, multiply the number of pixels by 20, then divide the result by 1,000 for the “rule of

thumb” power supply rating in Amps. Or use 60 (instead of 20) if you want to guarantee an absolute margin of safety

for all situations. For example:

60 NeoPixels × 20 mA ÷ 1,000 = 1.2 Amps minimum

60 NeoPixels × 60 mA ÷ 1,000 = 3.6 Amps minimum

The choice of “overhead” in your power supply is up to you. Maximum safety and reliability are achieved with a more

generously-sized power supply, and this is what we recommend. Most power supplies can briefly push a little extra

current for short periods. Many contain a thermal fuse and will simply shut down if overworked. So they may

https://learn.adafruit.com/adafruit-neopixel-uberguide

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WS2812 Scheda tecnica(PDF) 43 Page - Raspberry Pi Holdings PLC