Power supply and drivers

[TeoB]

Hello, I am working on a new led system. I would like to use ldd-700h drivers for powering 5 lines of 6 3w leds (3.6v each, 700mA), thus each line should be powered at 700mA and at least 18v. As in total I have 5 lines, my power supply should give at least 3.5A.

The meanwell RS-100-24 would do the job, giving 24v and 4.5A. However, on the technical sheet of the ldd drivers it is written that they should be powered at 650mA ( http://www.meanwell.com/mw_search/LDD-H/LDD-H-spec.pdf )
In my case they would be powered at 900mA ( 4.5 / 5 ), would this be too much or the driver will use anyway 650mA?

Thank you in advance for your help.

 

[mcgyvr]

Thats not how it works..
You aren't powering them at 900ma... They are only taking the current they need

 

[TeoB]

Thank you very much, that's good to hear.

And what happens if I power the line of 5 leds (18v needed in total) with 45v? I ask this because assuming I will get a power supply that erogate 48v, 3 are taken by the driver, in case I set the dimming at 100% each line would receive 45v, isn't it? Can this situation be dangerous?

 

[Gorgok]

Ldds are constant current drivers, as in they will take up to about 52V input and output whatever is needed to drive the string at the current they are designed for, like 700mA on a 700h. If you only hook up 1 3Vf LED to that setup you will get pretty bad efficiency, somewhere in the 60-65% range, but it would work. 18V would probably get you up to 85-90% range already, but it still is a little silly unless you have some other need for the higher volt supply...

At 100% dimming the string will only ever get the max current the thing is designed for, like the 700mA on the 700h. If that takes 3V or 40V just depends on the string, the driver will handle it though.

 

[TeoB]

Thanks, but sorry...the dimming on the ldd drivers is made on the amperes or on the volts?

 

[Gorgok]

It just turns it on and off. Fast.

Every fraction of a second its on its still at full power, limited by the driver.

 

[TeoB]

ok cool, thanks for all infos!

 

[Maryland Guppy]

Thanks, but sorry...the dimming on the ldd drivers is made on the amperes or on the volts?

You will need a device that provides a 5VDC PWM signal to dim LDD's

If the LDD's have no dimming signal they will run at 100% in your case 700mA
Some boards that allow multiple LDD drivers have a 10K ohm pulldown resistor
The LDD's will not function at all without a PWM signal if pulldown resistor is present.

 

[oreo57]

More specifically:
100Hz to 1kHz @ 2.5 to 6V range..


Ldd-l' s are different AND different by output.
small LDD-l's will only work w/ 3.5-8V which is why bluefish mini-s won't work w/ them.. PWM output is 3.3V..........(@100-1Khz)
larger ldd-l's are 100-500mHz @2.6-5.5V

 

[TeoB]

Yes, of course I have to buy a controller (I am thinking about the storm, but if I can find something in europe is much better).