Does anyone know how much current the data pin of the addressable RGB strip draws?

Thread Starter

Aleksey Shurtygin

Joined Dec 21, 2018
54
Hi!

Does anyone know how much current does the signal circuit draw on the ARGB strip that uses WS2815 chip (or WS2813)?
Can Arduino digital pin drive that?

I've tried to search online but all that is coming up are posts about LED power consumption and nothing about signal wires. Does it depend a lot on the chip or most of the time its similar across different strips? As for Arduino output pins according to my research they can provide max of 40mA. https://electronics.stackexchange.com/a/67094
The absolute maximum for any single IO pin is 40 mA (this is the maximum. You should never actually pull a full 40 mA from a pin. Basically, it's the threshold at which Atmel can no longer guarantee the chip won't be damaged. You should always ensure you're safelybelow this current limit.)
I've also looked at the WS2815 datasheet at http://www.normandled.com/upload/201808/WS2815 LED Datasheet.pdf but a bit confused by characteristics. They list Input Current at 1 µA. Is that the value I am looking for?


Now a little background for some high level understanding.

I am thinking of building a LED lighting in my living room controlled by the Arduino. Ideally I'd want to chain 4 strips together to make a 20m (60ft) line around the ceiling. I am trying to figure out how I will need to provide data to the ARGB strip from Arduino board and if Arduino will have enough juice for data or I will need some kind of amplifier or repeater or something else.

For now I am looking into following options:
1. Ideally chain all 4 strips together and use single Arduino digital output and connect to data to control all 1200 LEDs.
2. If that will be too much, I am considering connecting two chained strips in parallel and use two separate Arduino data outputs to control each 600 LEDs.
3. If that is still too much, I may have to split it up even more and use 3 or 4 data outputs and control them.

I'd appreciate any pointers.

Thanks

PS: the actual strip I am looking at is this one - https://www.amazon.com/gp/product/B07QGD3YHH
 

Thread Starter

Aleksey Shurtygin

Joined Dec 21, 2018
54
This is the basic diagram. It is not complete nor a working one. Just a pseudo-diagram to give some visual. Two power sources one to power the board and another to power the LEDs.

J1 would be a connector to a LED strip.
1 - Vcc+
2 - Data
3 - GND

upload_2019-5-16_14-55-46.png
 

btebo

Joined Jul 7, 2017
89
I have driven multiple strips' data inputs off of 1 Arduino output pin. So I don't think you should have a problem. However, the power required to light 1200 LEDs is going to be considerable. If you are making the LED white (RGB all on), running at full brightness, each LED could draw as much as 60mW of power. That's close to 15 amps at 5 VDC.

Adadruit.com has excellent info on these strips - look up their Neopixel tutorial.
 

Thread Starter

Aleksey Shurtygin

Joined Dec 21, 2018
54
I have driven multiple strips' data inputs off of 1 Arduino output pin. So I don't think you should have a problem. However, the power required to light 1200 LEDs is going to be considerable. If you are making the LED white (RGB all on), running at full brightness, each LED could draw as much as 60mW of power. That's close to 15 amps at 5 VDC.

Adadruit.com has excellent info on these strips - look up their Neopixel tutorial.
Yes, it will be power hungry. I've already done calculations and ended up at around 25 Amps @ 12V for that particular strip. According to their description its using 14.4 W/M which translates to a bit under 300W.
 

Yaakov

Joined Jan 27, 2019
1,547
I think you are going to find the problem will not so much be power but memory. The libraries to control the LEDs use a LOT.
 

djsfantasi

Joined Apr 11, 2010
5,612
Just a warning! The 40mA maximum specification is for a single pin. There is a 200mA total limit across all pins. So, you can’t have 6 pins, all driving 40mA because you’d exceed the 200mA total limit.

I don’t know how many pins your using.

Also, while you can drive 40mA from an Arduino pin, nothing says you should. When using an Arduino, I try to keep the load to no more than half that - 20mA
 
Last edited:

OBW0549

Joined Mar 2, 2015
2,986
However what is that VSS value under Input Current conditions? There is VSS=0V statement, but how do I find Vi now if VSS is 0, I can't do VDD/0, can I? :-/
Vdd is the positive supply voltage connection (+4.5V to +5.5V) and Vss is the negative supply connection, or GND. That's all it means.
 
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