SK6812 leds current draw when connected but not in use

Hi All,
While playing around with Arduino and SK6812 led strip I have noticed that even if all leds are black there is significant current usage.
My setup is Arduino mini pro and SK6812 led strip containing 50 leds.
I am using FastLed library for leds control.
Both leds and arduino are connected to capable power supply and all works nice when turned on.
Thing is, that when I set all leds to be black, so basically when I am turning off led strip, I can still see around 50mA of current usage.
After disconnecting led strip from power supply, curren usage drops to around 5mA. This is what arduino needs when active.

So it seems that my led strip uses nice 1mA per each led and I assume its just operational current of data line. Please correct me if I am wrong.

But when not using the led strip actively (not showing any color) I would expect it to not operate. And I would like to somehow reduce this current consumption if possible.

And here is my question. Is it possible? Did anyone approach this subject? Maybe there is a common solution that I am not aware of?

I started to think about some kind of relay or switch that maybe can be controlled by Arduino and just physically 'cut off' power line that goes into led strip when turning off leds. And then connecting it back when needed. What do you think, is this possible?

I was some time ago using N-mosfet to control 12V analog leds from arduino and maybe same idea can be used in this setup. As a 'relay'?
I am not really sure what electronics to use here with this 'physical' approach. Would be great if this can be adjusted programatically but I know there are limits and it might be not possible.

Would appreciate any help.
Thanks.

So it seems that my led strip uses nice 1mA per each led and I assume its just operational current of data line. Please correct me if I am wrong.

No it is the current needed to drive the chip that does the data decoding when sent data.

But when not using the led strip actively (not showing any color) I would expect it to not operate. And I would like to somehow reduce this current consumption if possible.

It is not simple because how is the chip going to know when it is going to receive data.

You could make the data output an input and then turn the power to the strip off. This would require you to have a switch like a P channel FET to power it down. It is likely that the losses that would introduce will waste any current savings you might get from this. Unless the LEDs spend a considerable time being off it is not worth it.

Grumpy_Mike:
No it is the current needed to drive the chip that does the data decoding when sent data.
It is not simple because how is the chip going to know when it is going to receive data.

Totally understand that when beeing active led strip needs this current to operate.
The idea was to reduce/cut off power to strip led only when its turned off. Arduino would be responsible to cut off power line when requested and turn it on back before sending request to light up leds.

Grumpy_Mike:
It is likely that the losses that would introduce will waste any current savings you might get from this. Unless the LEDs spend a considerable time being off it is not worth it.

Good point. I didnt consider the current used by the switch itself. Totally forgot about it.
For my scenario this 50mA are not so crutial. Just trying to optimize as much as possible. And I am bit dissapointed that strip uses the current while not beeing in use. Wasnt aware of that in the first place. Or to be more precise I wasnt aware of the amount of current used when just doing nothing.

As a note, each LED is connected to a chip that consumes power, led set to black or white, the chip still consumes power: see https://cdn-shop.adafruit.com/product-files/1138/SK6812+LED+datasheet+.pdf for power consumption of chip.

Grumpy_Mike:
This would require you to have a switch like a P channel FET to power it down. It is likely that the losses that would introduce will waste any current savings you might get from this. Unless the LEDs spend a considerable time being off it is not worth it.

I am still wondering about this current waste with mosfets. Do you have any particular example in your mind?
P or N fet that will handle 1A of load? Its getting bit offtopic but I am just curious about the numbers. Would it really use more than 50mA just for control?
Lets assume battery powered led light remotely controlled. When its turned off its really important to save battery and every mA matters. So if we can win some mA by using power cut off on led line then its a way to go right? Even if it requires more complicated wiring/hardware/software or all together.

SK6812 is not unique in this. Ws2812 uses around the same current per led when all leds are off. I suspect all the commonly used “neopixel” type chips are similar, but if anyone knows different, that would be interesting.

When its turned off its really important to save battery and every mA matters. So if we can win some mA by using power cut off on led line then its a way to go right?

Well it’s your project and so it is your call.

And indeed, the somewhat less than 1 mA per LED quiescent current is characteristic of these particular LED driver chips.

Why?

Frankly, I would simply call it just plain and simple sloppy design. The designer has decided that these are not intended ever to be used on battery power, so there is no need to design for zero "dark" current and it was easier to design some part of the chip - most likely the constant-current drivers - without concern to conserve current.

In general, the vast majority of current chips (digital but also analog) are CMOS and have virtually zero static current draw, so this is something of an anomaly but - there it is. :roll_eyes:

Let's see - 50 LEDs, maximum current draw just under 3 Amps, you could probably use one of these to switch the positive supply.

Paul__B:
Let's see - 50 LEDs, maximum current draw just under 3 Amps, you could probably use one of these to switch the positive supply.

Thanks for giving an example of suitable mosfet. Not sure if I am going to try it as I dont have equipment to solder so tiny elements. But if I try I will definitely share my results here.
Thanks!