Calculate Maximum LED Chips For This Driver

[Dan Shoemaker]

What is the maximum number of LED Chips that I can put on this driver?
I'm thinking of connecting all the chips that are on the same row in series such that the entire row of chips is in series. in some ways, each row will be Like a COB so each row is like one COB.
And then wire all the rows in parallel to each other. Such it's like wiring all the cobs in parallel.
How many chips per row can I have and how many of those rows can be in parallel?
I know that real manufacturers do other components when they combined series and parallel wiring but lets ignore that for the purpose of this topic. I can start a different thread about the nuances of the circuitry to deal with the other aspects of series/parallel wiring.
For now, I just seek your help in calculating how many chips max on this driver.

The table below has the specs for the LED chips I'm interested in.
The other table is the specs for the driver in question.


LED Chips above
Driver below


Thank you !
Dan

 

[Rocket Soul]

It will depend on the desired drive current per chip. Also, the chip info is missing info about voltage at 150mA.

 

[cobshopgrow]

if you want to drive them with the stated 65mA and your driver does 56V max its 18 leds in series and 160 in parallel when your driver is 10.4A.
120 lumen a watt isnt that great, i think you can have better strips for just a dollar from arrow.
tbc, 160 leds each led which is in series.

 

[Dan Shoemaker]

It will depend on the desired drive current per chip. Also, the chip info is missing info about voltage at 150mA.

Thank you so much cobshopgrow and Rocket Soul !
The desired current per chip is 65ma. The max volt at 150ma is 3.20v.

cobshopgrow, did I understand you correctly...I can put a maximum of 2,880 of those LED chips on that driver?

Is there a way to guesstimate if there's a point of diminishing returns when it comes to the PPFD.
In other words, is it possible that a much lower chip count could give almost as much PPFD as 2,880?
For example, maybe 1,200 chips would give a PPFD of 700 while only getting 750PPFD from 2,880?
I have no clue I'm only using that example to express my question about diminishing returns as measured by PPFD.
I know what PPFD is and I know that PPFD can only be measured after the lights are turned on and at the proper distance above the canopy (or floor if just measuring).

 

[grotbags]

Thank you so much cobshopgrow and Rocket Soul !
The desired current per chip is 65ma. The max volt at 150ma is 3.20v.

cobshopgrow, did I understand you correctly...I can put a maximum of 2,880 of those LED chips on that driver?

Is there a way to guesstimate if there's a point of diminishing returns when it comes to the PPFD.
In other words, is it possible that a much lower chip count could give almost as much PPFD as 2,880?
For example, maybe 1,200 chips would give a PPFD of 700 while only getting 750PPFD from 2,880?
I have no clue I'm only using that example to express my question about diminishing returns as measured by PPFD.
I know what PPFD is and I know that PPFD can only be measured after the lights are turned on and at the proper distance above the canopy (or floor if just measuring).

the 2880 is not a maximum thats if they are ran at 65ma, you could go to say 6000 and run them around 30ma.

but yes you will hit a wall of diminishing returns where exactly that wall is only you can decide... you could do with finding some more data on the diodes, you could do with a relative luminous flux vs forward current graph...

also worth bearing in mind is at some point the more diodes you run you will get to a point where you can no longer realistically dim the fixture as the diodes will be operating just over their minium volts/amps any less current and they will turn off....

 

[Rocket Soul]

if you want to drive them with the stated 65mA and your driver does 56V max its 18 leds in series and 160 in parallel when your driver is 10.4A.
120 lumen a watt isnt that great, i think you can have better strips for just a dollar from arrow.
tbc, 160 leds each led which is in series.

Another issue I see with the spec sheet is a bit suspect: if you check the "typcal LMFlux (Lum/w) @150ma" it's 130 while Lum/w is stated as 120 at 65ma. That's really strange and not how leds normally works, always greater efficiency with lower watts. OP:These calculations are only as good as the numbers you put in and I feel your spec sheet is a bit suspect here. Missing a few details and counterintuitive on others.

Some other issues: the voltage here is for chip only but I believe the actual board would ad some resistance. Maybe cobby knows better about this.

 

[cobshopgrow]

Another issue I see with the spec sheet is a bit suspect: if you check the "typcal LMFlux (Lum/w) @150ma" it's 130 while Lum/w is stated as 120 at 65ma. That's really strange and not how leds normally works, always greater efficiency with lower watts. OP:These calculations are only as good as the numbers you put in and I feel your spec sheet is a bit suspect here. Missing a few details and counterintuitive on others.

Some other issues: the voltage here is for chip only but I believe the actual board would ad some resistance. Maybe cobby knows better about this.

yes the board will ad some resistance but thats negligible for us, no datasheet will know the resistance in the end application .
the datasheet is really a bit strange, maybe 65mA and 150mA switched its postions by mistake here. ?.
idk, but you can calc almost all white leds with about 3V to get a idea.

btw. when you want to drive them with 150mA, you should go for 17 leds in seires max, the calc is very easy, divide the max volatge of your driver with the led voltage, 56/3.2 = 17,5, there is no half led, so its 17 max.

 

[cobshopgrow]

Thank you so much cobshopgrow and Rocket Soul !
The desired current per chip is 65ma. The max volt at 150ma is 3.20v.

cobshopgrow, did I understand you correctly...I can put a maximum of 2,880 of those LED chips on that driver?

Is there a way to guesstimate if there's a point of diminishing returns when it comes to the PPFD.
In other words, is it possible that a much lower chip count could give almost as much PPFD as 2,880?
For example, maybe 1,200 chips would give a PPFD of 700 while only getting 750PPFD from 2,880?
I have no clue I'm only using that example to express my question about diminishing returns as measured by PPFD.
I know what PPFD is and I know that PPFD can only be measured after the lights are turned on and at the proper distance above the canopy (or floor if just measuring).

like grotbags is saying, there is no limit to the bottom, driving lower, or almost no limit.
ill bet they will light up with a milliamp, at least i never encountered a problem even below 20mA a white led.
most signal leds these days are a milliamp or lower.

so practically i think its hard to overdo, ceiling space will be the limiting factor.
you normally always gain more ppfd when using more chips at the same wattage, not sure if your calculation fits.
grotbags said it all, there are graphs and sometimes even online calclualtors or exel sheets.
at least a graph is standard in a good datasheet.