# Powering an APA102 LED Light Strip

I am currently making a shopping list for an LED light strip (link) and I am getting 3m of it. Now, my main problem is powering that beast.

By my calculations, (42W * 3m) / 5V = 25.2A, if that is correct, that seems like an insane amount of power for such a strip, and any power supply I could find that was > 15A is just a barebones transformer.

They have listed that 42W/m is the maximum power draw, which I am not extremely likely to do, so I am currently looking at this power supply. Would it be sufficient?

• Do you mean, "I am not extremely likely to do", or do you mean "which I will not do, and I won't even try to draw 1/2 of that"? Unless you can unequivocally say it's the latter, you need a 25 amp power supply. Commented Jun 11, 2016 at 20:13
• @WhatRoughBeast Alright, I will start looking for some 25A supplies, thanks :) Commented Jun 11, 2016 at 20:23
• If you broke the strip into 5 60cm lengths and wired them in series (with some level shifting magic for the control data) you could possibly use a 24V 5A power supply, 25A is like 12awg cable or a 2mm solid copper bar or something, how on earth are they pushing 8A/meter through that little flex pcb? Surely the voltage drop alone...
– Sam
Commented Jun 12, 2016 at 0:28
• In addition to 'max' of 1W, the data mentions typical dissipation of each package as 0.2W; that suggests that 42 packaged lights per meter would typically draw 8.4W per meter, which might not be a bad typical-power estimate. 3 meters, 5A at 5V. Commented Jun 12, 2016 at 1:24
• @Tom On all the pages I could find, no one recommended higher than 24V otherwise it would kill the LED's. Also Each 1m segment has 144 LED's, so that's still 86.4W Commented Jun 12, 2016 at 23:06

If you choose to power a full 3 meter string from one end with one large power supply, you're going to have voltage drop problems I think at the other end and I think you're PCB traces will be hotter than you want if you drive them at full.

I suggest cutting the power and ground trace after each segment of 144 LEDs and powering each of the three segments with a separate 50W power supply. Just cut the PWR and GND traces of course...leave the data and clock lines intact.

The IRM-60-5ST from Meanwell is perfectly suited and you can buy from Mouser.

I have a feeling that the real world current draw from the APA102C is lower than the datasheet says when driving white (level 255 on all 3 colors).

Please post your real world current for driving 144 of these at full. Will be interesting to see. Maybe you can get by with a smaller power supply after all.

• It's probably better to just disconnect the +V connection and leave the ground in place, you might have some signal integrity issues otherwise
– Sam
Commented Jun 13, 2016 at 1:55