(yet another) 3 channel set-up, but with varying voltages

philnm · 12/13/2014, 07:01 AM

My set up consists of the following:

1. I've got my Arduino, programmed to take care of 3 channel PWM control.

2. I got my LED sets (divided into three channels, soldered, heat-sinked):

a. RED > 6-8 x 4 == 24-32v (900-1050) mA
b. BLUE > 9-11 x 3 == 27-33v (900) mA
c. WHITE > 30-36v x 1 == ~32v (3000) mA

3. I got a 12v Mean Well PSU (enough to handle all the amps and some more), a CC/CV boost converter, and another 48v Mean Well PSU.

I was going to get several LDD-1000H and LDD-700Hs (or LDHs, boost) to connect to the main PSU to power each LED channel ..

.. but I just found out that Mean Well LDD reduces Voltage by 3v, and LDH boosts it by 3.

So it is not really flexible to match my varying output voltage needs.

What can I do in this case?

I really would like to NOT to have 3 separate PSUs connected to LDD/Hs.

My ideas situation would be:

Code:

         
                  -> LDD-700H	-->  (RED)-(RED)-(RED)-(RED)
[Single Main PSU] -> LDD-1000H	-->  (WHITE)
                  -> LDD-700H	-->  (BLUE)-(BLUE)-(BLUE)
                             
			/\ 
			 |--[Arduino PWM]

Notes:

I will have the white chip extremely dimmed so 1000H (1000mA) is perfectly fine.
My main issue is reducing the number of PSUs to be attached to LDDs.
If at all possible, I'd like to NOT to have any resistors.

oreo57 · 12/13/2014, 08:05 AM

Quote:

Originally Posted by philnm

I really would like to NOT to have 3 separate PSUs connected to LDD/Hs.

My ideas situation would be:

Code:

         
                  -> LDD-700H	-->  (RED)-(RED)-(RED)-(RED)
[Single Main PSU] -> LDD-1000H	-->  (WHITE)
                  -> LDD-700H	-->  (BLUE)-(BLUE)-(BLUE)
                             
			/\ 
			 |--[Arduino PWM]

Notes:

I will have the white chip extremely dimmed so 1000H (1000mA) is perfectly fine.
My main issue is reducing the number of PSUs to be attached to LDDs.
If at all possible, I'd like to NOT to have any resistors.

The LDD will regulate the voltage based on the current and V(f).. You only need the one PS.. spec-ed to match the combined output..
V plus 3 for the max V(f) and Watt/Amp rating equal to the combined of the strings plus a safety factor of at least 10%..

philnm · 12/13/2014, 08:11 AM

oreo57, I'm about to be in tears from happiness and joy if this is the case and that little cheap device actually does it this way.

It says on the specs:

output voltage will always step down by 3 volts from input DC voltage

If my power supply provides 48v, and an LED string needs 27 @ 900mA, how would an LDD (900H, 1000H) drive it?

What happens to the difference of 18 volts between required 27v and 45v? (48 input - 3v of LDD = 45v)

Cheers!

Quote:

Originally Posted by oreo57

The LDD will regulate the voltage based on the current and V(f).. You only need the one PS.. spec-ed to match the combined output..
V plus 3 for the max V(f) and Watt/Amp rating equal to the combined of the strings plus a safety factor of at least 10%..

oreo57 · 12/13/2014, 08:29 AM

Quote:

Originally Posted by philnm

oreo57, I'm about to be in tears from happiness and joy if this is the case and that little cheap device actually does it this way.

It says on the specs:

output voltage will always step down by 3 volts from input DC voltage

If my power supply provides 48v, and an LED string needs 27 @ 900mA, how would an LDD (900H, 1000H) drive it?

What happens to the difference of 18 volts between required 27v and 45v? (48 input - 3v of LDD = 45v)

Cheers!

Well you got me there.. not sure exactly how the magic works (it is related to how a switching power supply works) but it does..

I guess you can think of the LDD as a variable resistor w/out the heat..

My most unbalanced LED fixture uses 4 LDD's to drive 4 strings w/ each strings combined V(f) from 9.6V to 44V running off one 56V constant voltage power supply..

What can I say, it just works.. All of this and a Typhon (Adruno based) controller tucked inside an old computer PS box..

as I said the LDD regulates the current by regulating the voltage out.. so it is the "valve" to the PS output...

http://www.nano-reef.com/topic/33047...-power-supply/

Quote:

LDD drivers are what are known as buck drivers. What that means is that they internally step down the voltage automatically based on the needs of the load. There are also boost drivers, which take a low voltage and make it higher, but those aren't all that common in our part of the LED world.

Reference:
http://www.arrownac.com/solutions-ap...eddrivers.html
http://4hv.org/print.php?plugin:forum.71561

philnm · 12/13/2014, 12:13 PM

OK oreo57, understood! You made my day and the links you shared have been really helpful (as were you!)

Cheers!

P.S. One more thing: Do you know if I can parallel connect two LDD-1000Hs to get 2A of output? I'm searching the forums but couldn't find a clear answer on this either.

Quote:

Originally Posted by oreo57

Well you got me there.. not sure exactly how the magic works (it is related to how a switching power supply works) but it does..

I guess you can think of the LDD as a variable resistor w/out the heat..

My most unbalanced LED fixture uses 4 LDD's to drive 4 strings w/ each strings combined V(f) from 9.6V to 44V running off one 56V constant voltage power supply..

What can I say, it just works.. All of this and a Typhon (Adruno based) controller tucked inside an old computer PS box..

as I said the LDD regulates the current by regulating the voltage out.. so it is the "valve" to the PS output...

http://www.nano-reef.com/topic/33047...-power-supply/

Reference:
http://www.arrownac.com/solutions-ap...eddrivers.html
http://4hv.org/print.php?plugin:forum.71561

perkint · 12/14/2014, 05:37 AM

The meanwell LDD data sheets are not the best worded in the world, but as Oreo57 says, they will do what you want

The LDD-H range will take an input voltage of 56V and output only 2V if that is the voltage required by whatever you have connected (eg a single red LED). From the datasheet:
* Wide input voltage: 9 ~ 56VDC
* Wide output LED string voltage: 2 ~ 52VDC

The 3V bit is saying you can't give it 12V and expect it to output 12V - it means for 12V output you need to give it 15V input. Their maths doesn't quite work at maximum, as it has a max in of 56V and max out of 52V, which by my reckoning is 4V, but i suppose you can let them off that 1V disparity an max

Tim

philnm · 12/14/2014, 08:54 AM

Thanks perkint! It made my day to hear this yesterday. It's so hard to find something of good quality in terms of an LED driver with PWM support. God bless MeanWell for the LDD series

BTW - Any chance you could help me out with the second question I have?

Is it possible to parallel connect 2 LDD-1000H's to get 2 amps out? Would it work fine and as expected?

Quote:

Originally Posted by perkint

The meanwell LDD data sheets are not the best worded in the world, but as Oreo57 says, they will do what you want

The LDD-H range will take an input voltage of 56V and output only 2V if that is the voltage required by whatever you have connected (eg a single red LED). From the datasheet:
* Wide input voltage: 9 ~ 56VDC
* Wide output LED string voltage: 2 ~ 52VDC

The 3V bit is saying you can't give it 12V and expect it to output 12V - it means for 12V output you need to give it 15V input. Their maths doesn't quite work at maximum, as it has a max in of 56V and max out of 52V, which by my reckoning is 4V, but i suppose you can let them off that 1V disparity an max

Tim

oreo57 · 12/14/2014, 09:51 AM

Quote:

Originally Posted by philnm

Is it possible to parallel connect 2 LDD-1000H's to get 2 amps out? Would it work fine and as expected?

No.. Best to go w/ An ldd-l @ 1500mA..
Max V(f) is 36V

http://www.meanwell.com/search/LDD-L/LDD-L-spec.pdf

perkint · 12/14/2014, 11:40 AM

+1 to the above - it doesn't work. Not sure why (i assume the current sensing on each one gets confused due to the input from the other), but it doesn't work.

Tim

philnm · 12/15/2014, 06:02 PM

Naughty LDD but alright

Cheers everyone for your kind help.

in2infinity · 12/15/2014, 09:36 PM

While you can't run them in parallel to get 2 amps, you can run multiple LDDs from a single PWM to have more LEDs controlled from one pin if your objective is to get more light from a single PWM output. Just remember that an Arduino digital out is limited to 40 mA. My understanding is that the PWM pin on an LDD pulls less then 1 mA on its own, and about 1mA if you use a 10K pull down resistor to kill the lights if the arduino power fails.

12/13/2014, 07:01 AM	#1
philnm Registered Member Join Date: Dec 2014 Posts: 11	(yet another) 3 channel set-up, but with varying voltages My set up consists of the following: 1. I've got my Arduino, programmed to take care of 3 channel PWM control. 2. I got my LED sets (divided into three channels, soldered, heat-sinked): a. RED > 6-8 x 4 == 24-32v (900-1050) mA b. BLUE > 9-11 x 3 == 27-33v (900) mA c. WHITE > 30-36v x 1 == ~32v (3000) mA 3. I got a 12v Mean Well PSU (enough to handle all the amps and some more), a CC/CV boost converter, and another 48v Mean Well PSU. I was going to get several LDD-1000H and LDD-700Hs (or LDHs, boost) to connect to the main PSU to power each LED channel .. .. but I just found out that Mean Well LDD reduces Voltage by 3v, and LDH boosts it by 3. So it is not really flexible to match my varying output voltage needs. What can I do in this case? I really would like to NOT to have 3 separate PSUs connected to LDD/Hs. My ideas situation would be: Code: -> LDD-700H --> (RED)-(RED)-(RED)-(RED) [Single Main PSU] -> LDD-1000H --> (WHITE) -> LDD-700H --> (BLUE)-(BLUE)-(BLUE) /\ \|--[Arduino PWM] Notes: I will have the white chip extremely dimmed so 1000H (1000mA) is perfectly fine. My main issue is reducing the number of PSUs to be attached to LDDs. If at all possible, I'd like to NOT to have any resistors.

12/14/2014, 05:37 AM	#6
perkint Registered Member Join Date: Jan 2014 Location: Robin hood country, UK Posts: 817	The meanwell LDD data sheets are not the best worded in the world, but as Oreo57 says, they will do what you want The LDD-H range will take an input voltage of 56V and output only 2V if that is the voltage required by whatever you have connected (eg a single red LED). From the datasheet: * Wide input voltage: 9 ~ 56VDC * Wide output LED string voltage: 2 ~ 52VDC The 3V bit is saying you can't give it 12V and expect it to output 12V - it means for 12V output you need to give it 15V input. Their maths doesn't quite work at maximum, as it has a max in of 56V and max out of 52V, which by my reckoning is 4V, but i suppose you can let them off that 1V disparity an max Tim

12/14/2014, 11:40 AM	#9
perkint Registered Member Join Date: Jan 2014 Location: Robin hood country, UK Posts: 817	+1 to the above - it doesn't work. Not sure why (i assume the current sensing on each one gets confused due to the input from the other), but it doesn't work. Tim

12/15/2014, 06:02 PM	#10
philnm Registered Member Join Date: Dec 2014 Posts: 11	Naughty LDD but alright Cheers everyone for your kind help.

12/15/2014, 09:36 PM	#11
in2infinity Registered Member Join Date: Sep 2014 Location: Cleveland, OH Posts: 4	While you can't run them in parallel to get 2 amps, you can run multiple LDDs from a single PWM to have more LEDs controlled from one pin if your objective is to get more light from a single PWM output. Just remember that an Arduino digital out is limited to 40 mA. My understanding is that the PWM pin on an LDD pulls less then 1 mA on its own, and about 1mA if you use a 10K pull down resistor to kill the lights if the arduino power fails.