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Can i use CC led supply to connect LED both in series and parallel

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No_One

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Hi everyone,

Pretty noob question i think, but i'am mostly DYI electronics guy with little knowledge :)

Example CC PSU

LED i want to use is Cree XP-E (Red rated 700mA, Royal Blue rated 1A) and XM-L2 reted for 3A. While i don't want to have multiple PSUs can i use same CC PSU and use both series for 3A LED and include several parallel circuits for XP-E to give them 700mA?

If it is possible while Red and Royal Blue have slightly different specifications is it ok to have them both in one parallel circuit?

BR and thank you!
 

The CC supply you were referring (LPC-60) has a current capability of
1.05A to 1.7A only (depending on model) .

you cannot use it for 3A LEDs.
 

i'am referring to:

Operation Mode: Constant Current (CC)
Output Current-Channel 1: 1.4 A
Output Voltage-Channel 1: 9 VDC to 42 VDC

While XM-L2 runs 350-3000mA they are running fine..
 

Hi,

Post the datasheet, not the shop page :). If the PSU has to sense a load of parallel strings, surely it would need multiple constant current sources to sense each string, or the designer would need to do a very delicate balancing act to match the load on every string, presumably bearing in mind temperature effects and more, a bit of a Swiss watch-maker's task, and I suspect not wholly realistic. While I'm sure you could get away with it, and hopefully no string would win the current-hogging race and get all greedy and frazzle, it sounds like a dodgy method I would not employ myself for any serious project.

There are plenty of LED driver ICs which can monitor from a few to many strings, with protection circuitry included, I'd have gone that way myself - one whatever is big enough power supply and a few LED driver ICs, but still.
 

Cree XP-E (Red rated 700mA, Royal Blue rated 1A) and XM-L2 reted for 3A is a good choice, you could try to select more convenience one.
 

Hi,

Post the datasheet, not the shop page :). If the PSU has to sense a load of parallel strings, surely it would need multiple constant current sources to sense each string, or the designer would need to do a very delicate balancing act to match the load on every string, presumably bearing in mind temperature effects and more, a bit of a Swiss watch-maker's task, and I suspect not wholly realistic. While I'm sure you could get away with it, and hopefully no string would win the current-hogging race and get all greedy and frazzle, it sounds like a dodgy method I would not employ myself for any serious project.

There are plenty of LED driver ICs which can monitor from a few to many strings, with protection circuitry included, I'd have gone that way myself - one whatever is big enough power supply and a few LED driver ICs, but still.

OK, LPC-60-1400

This is true LED supply/driver, no need for multiple drivers..., what it does is provide 1400mA current and variable voltage depending on LED needs, LED decides when to pull 2,85 or 3,05 V and it depends on current, temp, etc...

While my LEDs rated differently but they all can run in 1400mA or 700mA (in parallel) my only concern here if i can combine Red/Blue in one circuit, while they rated differently they will pull different Voltage.

While writing this i think it will be OK while more demanding LED will be the first one, if first pulls 2,95@700mA and second pulls 2,85@700mA i think i should be fine...
 

the current is fixed.
the voltage on the chain of LEDs will be based on the characteristic curve of them at that current.
 

Yes, but will it will be ok if i have 1,4A>2x0,7A (in parallel)> 1,4A >1,4A, > 2x0,7A (in parallel)>1,4A will every led in chanin especially paralleled once will get Voltage they need?

**broken link removed** lets look @350mA red has 2.1Vtyp@350mA and RoyalBlue has 3.1Vtyp@350mA what wil happen if i parallel them? If i would have 700mA CC driver lets say 5-12V then they both receive 350mA but will driver will manage voltage correctly?
 

the final voltage from the driver settles at 700mA current point.
In your case the voltage is decided by the characteristic curve of the 2.1v RED and 3.1V Green.

You have to connect them in parallel and mesure the final voltage.
A possibility of >2.1V applied on RED LED.
 
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    No_One

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Any difference witch LED goes first in parallel circuit? Maybe one with higher voltage better to go first?
 

can you give some more info on what do you mean by 'Any difference which LED goes first in parallel circuit?
 

Not the best example but still:

litlpo_SeriesParallelLEDPict.png


Last 3 led RRG would make a difference if they go GRR according to my case?
 

Last 3 led RRG would make a difference if they go GRR according to my case?
No difference whatsoever because they are in series. Still the same current will go through and hence same voltage drop for the RRG or GRR case.
 
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    No_One

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if you mean to say the three LEDs in parallel as:
RRG -one triplet in pair
and
GRR-another in parallel wiring
then it doesnt matter which one is connected.
 
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    No_One

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OK, guys, thanks everyone!
 

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