WS2811

Hello, i ordered 1m 30led 12V WS2811 strip. But i dont hnow how its about current draw... can anyone please calculate it? thanks

I have a 50 led string for 5V, it draws:

Off: 0.02A
Green: 0.66A
Red: 0.66A
Blue: 0.66A
White: 1.8A

The above is at full brightness, reducing the brightness you can get anything between the off and the white current draw.

i ordered 1m 30led 12V WS2811 strip

The strip's LEDs take 20mA each per colour, but with a 12 V strip you have three LEDs in series. The current does not add up with LEDs in series.

So each set of three LEDs will take 20mA * 3 = 60mA - the 3 is because of the three colours. If you have white in there make it 4.

So for 1m of 30 LEDs per meter you have 30/3 = 10 sets of LEDs, giving an overall total of
60mA * 10 = 0.6A

When looking to buy a power supply always get one that can provide at least 20% more current than you need.

Grumpy_Mike:
The strip's LEDs take 20mA each per colour, but with a 12 V strip you have three LEDs in series. The current does not add up with LEDs in series.

If you can address 30 positions on a 30 led strip they do not use series between the leds, but only internal in each bulb.

Grumpy_Mike:
So each set of three LEDs will take 20mA * 3 = 60mA - the 3 is because of the three colours. If you have white in there make it 4.

As you can see above I got 0.66A for 50 leds or about 13mA for each led (The datasheet specified 18.5mA).

Tobias, please post a link to your stripe so Grumpy and HKJ can see WHAT you are really using.
And by the way: why can't you upload a sketch lighting the first pixel in white, see how many LEDs are getting on (I guess 3) and measure the current? Current for one Pixel x 30 or x 10 should do the math :wink:

According to the datasheet a 12V setup will mean each chip uses 2.6mA for its power supply or a total of 80mA (0.08A) for a 30 led string with individual addressable leds (i.e. no grouping of 3 leds), this would be the current when no leds are on.

I sort of doubt that the leds are grouped, it would be very messy with the wiring. This makes my guess about 1.1A for a 30 led strip when all 30x3 (or 30x9) leds are full on.

HKJ-lygte:
I sort of doubt that the leds are grouped, it would be very messy with the wiring. This makes my guess about 1.1A for a 30 led strip when all 30x3 (or 30x9) leds are full on.

I don't think we are worried about your doubts as to whether the LEDs are grouped or not! :roll_eyes: The matter is simply not in dispute. :grinning:

Here is a picture of a 12 V LED strip. Click to zoom.

Note that there is one chip for each three LEDs. Also note that these LEDs have six terminals, so that the anode of the first (nearest the chip) goes to the corresponding colour cathode of the next LED.

With that type: No
And I expect it is that type he has got, that would reduce my above current estimate to 1/3.

I was thinking about this type

And I would be very surprised if they grouped led there.

Well, you have illustrated 5 V LEDs. I believe we were discussing 12 V LEDs.

Paul__B:
Well, you have illustrated 5 V LEDs. I believe we were discussing 12 V LEDs.

The announcement for that chain was 12V leds.

Can you post it?

Paul__B:
Can you post it?

Just search for "ws2811 12V" on ebay or Aliexpress, here is one result where you can select between 5V and 12V:

https://www.aliexpress.com/item/33038704798.html


OK, I'll pay that. :grinning:

Quite a bizarre arrangement insofar as at full brightness, the IC will be dissipating half a watt. Apparently the advantage is that 12 V power supplies are more readily available than 5 V supplies.

It appears the only actual difference between the two boards is the value of the resistor which feeds the on-board Zener in the chip.

150 Ohm for the 5 V, 2k7 for 12 V.


Seems this has been discussed before (not surprisingly). :grinning:

Resistor and zenner gonna get toasty

Well, given the right resistor value, the WS2811 requires only a small current for its background operations - as it is with an ATmega but a lot less (nominal 2.6 mA).

But dropping the difference between the voltage of a single LED and 12 V at 20 mA is a serious matter (160 mW per channel).