Seems like my strip of about 1 meter is drawing over 100 ma even when all the lights are off. I wasn't planning this so my solar charging system can't keep up...
First, does that seem right?
Second, should i just put in a relay on the power lead and turn is on only during the lights "on cycle period" to eliminate the draw when I don't need the lights?
Thanks!
Steve
The datasheet for the WS2812B says the quiescent current is 0.6 mA (that's per LED unit). This is a downside of the addressable LEDs. There's a little IC running in each of those LED units constantly, whether the LEDs are on or off.
Yes, its normal.
Don't use a relay, they are not very power efficient.
Maybe try an n-channel MOSFET with a logic-level gate, such as IRL520 or STP16NF06L. This would go between the -Ve connection to the strip and ground.
What do other members think? Would a p-channel MOSFET be more appropriate?
Either way, it would be important to prevent the strip from being parasitically powered by the data line from the Arduino. So a resistor ~470R on the data line would give some protection, but it might also be wise to change the data pin to INPUT when the LEDs are off.
Wow....thanks so much for the reply! I'm afraid the proposed solution (other than the resistor) is beyond my pay grade....but I'll do some research to see if I can figure out the proposed circuit.
I like the idea of changing the data pin to an input, then back again when I need the lights on....That should work..right? I thought the draw was on the 12v, not the data pin, but I'm still learning!
Steve
I thought the draw was on the 12v
It is. If you cut the 12V supply using any method, relay, MOSFET, whatever, the chips on the strip may try to power themselves from the data line, which could, at worst, damage them and the Arduino, and at best simply result in wasted current draw by a different route. You see, there is an important rule which says that the voltage on any pin of any chip must not significantly exceed the chip's Vcc pin. If that happens, this damaging "parasitic powering" can occur. The rule applies to the chips on the strip as much as the Arduino's chips or any other chips in your circuit. If you cut the 12V supply while there is 5V signal on the data line...
Thanks again! So you think the changing to input and back again is my best shot?
If not, could I use 2 relays (data pin and 12v) on the normally open side and close them up when I use the LED strip...I am only using the LEDs for 3 hours during the night period. This would reduce the loss from pulling in the relays to a much shorter time and protect the circuit?
Steve