Meanwell LDD driver: for those who want to dim to 0 using Arduino

[patrikk]

Looks like it would work, to me.

I don't think you should put resistors on there. You'd be burning a pile of power in the resistor trying to get the voltage drop up to 24V. I assume you're doing it to try to get up to closer to 24V? It's not necessary because the driver has components that already do what you're trying to do much more efficiently.

The spec sheet for the LDD I posted above shows the efficiency with different input voltages for different numbers of chips, and it's not terrible even if you're only putting 7 volts of LEDs on a 24V power supply. But why not do 1 String of 4 green and 1 string of 4 blue and 1 string of 4 red? Fewer LDD-700H to buy, and they'd run more efficiently.

Edit: here's link to spec sheet. Go to graphs on the last page and look at the one for 24V input. http://www.meanwell.com/search/LDD-HW/LDD-H-spec.pdf

the reason for the additional channels are because half of them are placed together and the other haft will be on another heat sink/group. That way I can increase the light from left to right or vice versa ( sunset sunrise) .

thank you for the link missed that the range output before.

edit:
btw Does anyone know of any meanwell PS that has an output of 24V 9A that is encapsulated similar to a PS for a laptop?

 

[sfsuphysics]

the drivers should regulate the voltage across the leds so you dont need to regulate it with resistors

 

[Eud]

btw Does anyone know of any meanwell PS that has an output of 24V 9A that is encapsulated similar to a PS for a laptop?

24V at 9A is 216W. That's a decently large power supply. A non-laptop one is

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_194782_-1

But I'm not sure you'd really need a 200+ Watt power supply. I think you'd need much less. I know you're adding up the amps on each channel and coming up close to 9A, but it's not that simple.

I believe that they way that these LDD drivers do their DC-DC conversion and end up with the rated current is that they vary the voltage supplied in order to keep that current and therefore the input current is less than the output current.

So while you'll read 700mA on the output side of an LDD driver, if you are only running 2 LED's on it it's only dropping 7 Volts out of 24 Volts and you'll measure much less than 700mA current on the input side as a consequence of how it does the DC-DC conversion. Otherwise it would have to be burning up (24V-7V)*0.7A = 11Watts of power in the driver similar to your resistor idea, which it is definitely not doing.

O2Surplus or tomservo or rrasco seem to be the recent guys doing measurements like this. Do I have that right?

 

[sfsuphysics]

Response from MeanWell.

Hi Jared,
Yes, if you have a 10V/500mA power supply, the LDD-1000H can turn your
3V LED on.

Well that settles that, it just strikes me as odd that it says 900mA input current at full power on the spec sheet. Either way, I wish there were some places that had these in the $5 range, and not the double the price Mouser ones.

 

[one clownfish]

Could someone tell me if this would work:

one PS (24V 9A)

2x strings of 6 Cree XML CW at 1A about 3,3V
4x strings of 6 Cree XT-E RB at 1A about 3,3V
6 LDD-100H

one PS (24V 9A)
2x strings of 2 Cree XP-E Green at 0,7A 3,3V
2x strings of 2 Cree XP-E Blue at 0,7A 3,3V
2x strings of 2 Cree XP-E Red at 0,7A 2,3V
2x strings of 5 UV led 0,7A and about 3,5V
8 LDD-700H

I personally wouldn't waste the money driving the XM-L LEDs at only 1Amp. I'd go with the XP-G, they can be driven to 1.5 amps for half the money. The XM-L's are not anymore efficient driven at that low of a current. Check out the Cree data sheet.

 

[patrikk]

Could someone tell me if this would work:

one PS (24V 9A)

2x strings of 6 Cree XML CW at 1A about 3,3V
4x strings of 6 Cree XT-E RB at 1A about 3,3V
6 LDD-100H

one PS (24V 9A)
2x strings of 2 Cree XP-E Green at 0,7A 3,3V
2x strings of 2 Cree XP-E Blue at 0,7A 3,3V
2x strings of 2 Cree XP-E Red at 0,7A 2,3V
2x strings of 5 UV led 0,7A and about 3,5V
8 LDD-700H

I personally wouldn't waste the money driving the XM-L LEDs at only 1Amp. I'd go with the XP-G, they can be driven to 1.5 amps for half the money. The XM-L's are not anymore efficient driven at that low of a current. Check out the Cree data sheet.

I would also want to go 2000mA on the XML led but there isnt at this point any meanwell LDD for 2000mA so I thought I get PS and the LDD driver and place them on a socket making it very simple to change them when meanwell makes a 2000mA ( I hope they do). are there any other drivers that handle 2000mA that are efficient like the meanwell ones and similar size? I've heard people talk about the puck buck but aren't they more of a lower quality ? (I get the feeling that mean well are quality but hey I might be wrong).

if anyone has any similar suggestions for drivers as the LDD that is considered to be higher quality I would be interested.

 

[zachts]

I personally wouldn't waste the money driving the XM-L LEDs at only 1Amp. I'd go with the XP-G, they can be driven to 1.5 amps for half the money. The XM-L's are not anymore efficient driven at that low of a current. Check out the Cree data sheet.

Sorry I beg, to differ here. Directly quoting data sheets the xml is just under 20% more efficient than an xpg cool white (comparing r5 xpg to u2 xml)
xpg = 348 lumens @ 1amp 3.15 volts (3.15 watts, 110.48 lumen/watt)
xml = 416 lumens @ 1amp ~3.0volts (3.00 wats, 138.67 lumen/watt)

 

[zachts]

I would also want to go 2000mA on the XML led but there isnt at this point any meanwell LDD for 2000mA so I thought I get PS and the LDD driver and place them on a socket making it very simple to change them when meanwell makes a 2000mA ( I hope they do). are there any other drivers that handle 2000mA that are efficient like the meanwell ones and similar size? I've heard people talk about the puck buck but aren't they more of a lower quality ? (I get the feeling that mean well are quality but hey I might be wrong).

if anyone has any similar suggestions for drivers as the LDD that is considered to be higher quality I would be interested.

stay tuned, we are very close to a definitive answer on how to wire two LDD-1000 to get 2000mA to one LED!

 

[one clownfish]

Sorry I beg, to differ here. Directly quoting data sheets the xml is just under 20% more efficient than an xpg cool white (comparing r5 xpg to u2 xml)
xpg = 348 lumens @ 1amp 3.15 volts (3.15 watts, 110.48 lumen/watt)
xml = 416 lumens @ 1amp ~3.0volts (3.00 wats, 138.67 lumen/watt)

Yep, your right. Thx for correcting me, XM-L's are 16.4% more efficient. For some reason 10% and $10/pcs. was in my head. I didn't know they came down in price so much either.

 

[daplatapus]

Edit: re-thought my post

 

[zachts]

Yep, your right. Thx for correcting me, XM-L's are 16.4% more efficient. For some reason 10% and $10/pcs. was in my head. I didn't know they came down in price so much either.

generally speaking though you weren't totaly off the mark, the main reason to use them is to run them over 2 amps and get more light for less initial cost when compared to multiple xpgs and or to get very intense points of whit light for shimmer, etc. they can crank out somthing like 900+ lumens up around thier 3 amp mark. making the ~6.50 price point pretty attractive v.s. 3 xpg at around 5.00. but trade offs both ways here.

:beer:

 

[patrikk]

another advantage of using XML leds is that they produce less heat then the XPG for more lumens.

stay tuned, we are very close to a definitive answer on how to wire two LDD-1000 to get 2000mA to one LED!

really! sounds interesting link?

 

[Eud]

really! sounds interesting link?

The past two pages of this thread are about O2Surplus and others trying to figure out how to run them in parallel without burning them up. Seems like they're getting close. Scroll up.

 

[sfsuphysics]

Sorry I beg, to differ here. Directly quoting data sheets the xml is just under 20% more efficient than an xpg cool white (comparing r5 xpg to u2 xml)
xpg = 348 lumens @ 1amp 3.15 volts (3.15 watts, 110.48 lumen/watt)
xml = 416 lumens @ 1amp ~3.0volts (3.00 wats, 138.67 lumen/watt)

Also note both of these falter because these numbers are using the old system of a 25°C temperature which is highly unrealistic (personally I'd like to see a system they test with to put 2 amps through one of these and keep it at 25C, unless they just "flash it" to try).

Not saying this efficiency difference would change much at a realistic temp (in fact the graphs look literally identical for how much they drop as temp rises), but it also doesn't take into account efficiencies when 'run at what they should be run' type of arguments, so if you push 3 amps through an XML you are not going to get the efficiency of running 3 XPGs at 1 amp, which the later would cost you a little bit more but it all matters what you are looking for out of your setup cost savings or energy efficiency for light output or some combo of the two.

 

[zachts]

I'm guessing they were runing them in the freezer LEDs love the cold!

I'd wager same test set up as used on their new mk-r that supposedly can get 200 lumens per watt. just not at the realistic currents listed on the data sheet........... it's only a little better than an xml.

 

[AMDphenomx4]

I'm guessing they were runing them in the freezer LEDs love the cold!

I'd wager same test set up as used on their new mk-r that supposedly can get 200 lumens per watt. just not at the realistic currents listed on the data sheet........... it's only a little better than an xml.

I'd wager if compared max output to max output with 3A for the XM-L and 1.25A for the MK-R, the MK-R is about 50% more efficient. Feel free to run the numbers and do the little bits of math to get them either both to 85C or both to 25C.

 

[djmx2002]

maybe someone here could help me, I've just got my order of LDD 700L. I hooked everything up, and the led lit, However i am unable to dim it at all!

does anyone have any idea what am i doing wrong?

tried the basic fade sketch. and also setting PWM output to 0, 100 and 255. the light intensity remains the same

 

[tomservo]

Did you connect the ground of your PWM source to the Vin- pin of the LDD?

 

[djmx2002]

Yep that what it was, took me a while to figure it out this driver works amazingly. I got the 4095 steps 16 channel pwm from adafruit.

 

[Ronic]

My LDD's are on the way, but does anyone have any spare 5up LDD boards?