Ldd "5up" board with separate volt inputs?

[jt41time]

I have been looking for a 5up board for my ldd drivers. But I need one with sperate voltage inputs. A couple of my led strings are 2.2v instead of 3 or so volts. So I will need to have a separate power supply.

Unless there is an easier way to do it.

2 strings of 10 at 3.2 each. 32v....
1 string of 5 at 2.2 each. 10.1v
1 string of 5 at 3.0 each. 15v
1 string of 5 at 2.8 each. 14v

Separate pwm control of each channel. Rgb + white.

Drive them all at 3v and step down the one?

Suggestions plz

 

[gus6464]

The voltage is irrelevant as long as the total amount does not exceed 48v per ldd. It doesn't matter if you have 10v or 35v per string. All that is required is a power supply that can handle the max voltage you have on the highest string so in this case 32v. The number that needs to be known is the total current for the entire setup to buy accordingly.

 

[jt41time]

Right. But if the PS is at say 36v for the 2 strings. It needs be almost half that for the other 3 strings.

 

[NanoReefWanabe]

Wouldn't one PS with enough voltage to cover all the strings plus 2-3v per ldd diver be the best bet then just run all the drivers in parallel? You would need like 85 volts or so I would think....even if you hugely over shot the voltage I don't think it matters as long as there is enough current to cover your driver's...ie you can't put 1A through a 700mA driver. My understanding is if you want to run 5 1A drivers you would need a PS that is ~85V @5A...if your strings run at less then 1A then add the mA ratings and use the appropriate size driver keeping in mind the total voltage as well. That said a3.5A 85V power supply will not work if you intend to run 1A ldd's...

 

[gus6464]

Right. But if the PS is at say 36v for the 2 strings. It needs be almost half that for the other 3 strings.

That's not how LDDs on an LDD board work. It doesn't matter if one LDD is only using 10v vs 35v on another. What matters is the total amps for the entire setup. So if you have 5x700ma LDDs you need a PSU that can push 3.5A minimum. So you would need a 48v 4A PSU.

If you have 5x 1000ma LDDs you need a 48V/6A PSU and so on.

 

[jt41time]

So what do I do with a string that requires much less voltage then another?

 

[mcgyvr]

So what do I do with a string that requires much less voltage then another?

Does not matter provided 1 series string per LDD...
The LDD provides constant current to the string..

You can also mix different voltage LEDs in the same string provided the current requirements are the same..

Example..
LED #1 = 2V @1000mA
LED #2 = 3V @1000mA..

Both can be in the same string without issue provided that the sum of the LED Vf is less than the max DC output voltage of the system.. Which is typically 2-3V less than the power supply voltage..

 

[oreo57]

So what do I do with a string that requires much less voltage then another?

Basically the LDD is a voltage regulator that sets the output voltage to match the rated mA...

Feed it all the voltage it can take.. IT will regulate the voltage out..

 

[jt41time]

Well then. That's great news. I thought it outputted the input voltage (-4 or so volts.....) right on thank you everyone. My build will much easier now.

 

[oreo57]

Well then. That's great news. I thought it outputted the input voltage (-4 or so volts.....) right on thank you everyone. My build will much easier now.

no the minus volts are the voltage differential required by the LDD.
A 48V power supply will only have about 45V "available" on the output..

 

[mcgyvr]

Yep.. The LDD basically eats up 2.5V (or whatever the spec is) for itself..
So if you feed it with a 48V constant voltage power supply then it has the potential maintain the constant current for an LED string with up to a 45.5Vf (forward voltage drop).

If the summed Vf of the LEDs is less then its still delivering the fixed output current.
LEDs are current driven devices not voltage like a lightbulb, resistive load, etc.. that will regulate its own current/wattage based on its resistance..