I have been using cobs for a couple of years aqnd decided it was time for change. I was watching various folks with their designs and I decided I wanted to make the move to Samsung s6 bin diodes capable of 207lm/w max if driven properly.
I started research. I learned two things for Constant Current design. One, you decide what power you want the board to deliver, and two what drive current you want to use for the board. The third item is how to drive the board economically and efficiently.
Starting from item three economy and efficiency. Samsung diodes are most efficient when driven between 150mA and 165mA a very narrow band given the diode can be driven at 200mA max. Keeping this in mind on to item one.
I decided I wanted a board to deliver 200w to replace existing 200w cob rigs I have. I wanted to reuse as much of my equipment as possible from heat sinks to drivers etc. everything. The majority of my drivers are
HLG-185H-C1400B drivers. I decided I was not going to use 1400B drivers because the only other companion would be a C700B driver. More on that thought later.
I decided a better driver would be to go with a
HLG-185H-C1050A/B driver. I had a few of these so that would also support the reuse approach. The C1050 driver has a drive current of 1050mA and a max Forward Voltage of 185v. Those are my two targets now to focus my design parameters on.
I now have a target of 200w, 1050mA, 185v, and a current range of 150-165mA per diode.
First step. Decide how many diodes to use in the design. I want6ed to use as many diodes as I couldwhile be economical and efficient. I contacted a manufacturer in ShenZhen China and discussed my parameters. Their primary point is there are 2500 diodes on a reel of Samsung S6 LM5661C diodes and a reel cost about $150 per reel. I decided on two reels as I wanted to use two Spectrum 5000k 80cri and 3000k 90cri to be used in unison or separate. I would decide that later.
With this info I did some calculations. I decided I would go with 384 diodes on each board for a total of thirteen boards for 2496x2 leaving 8 diodes for the manufacturer to keep. Now the trick is to drive 384 diodes at 150mA.
I decided to accomplish this easily with two colors was to go with two channels with 192 diodes on each channel. Now comes the hard part, how to configure 192 diodes correctly fort the desired outcome.
I developed a strategy. A circuit in series has additive voltage, while a parallel circuit has additive amps. Each diode has a forward voltage of 2.9v and a target of 150mA.
So I looked at how Samsung does it. They use a circuit of 8 diodes in series with three parallel rows to get their hard stips to work at 200mA. SO I decided again I would work with that same rationale to start with, but I think bigger, So I multiplied the 8 by 4 and came up with 32 diodes in series that gave me 92vf; forward voltage. excellent.
Now comes the harder part creating a balanced parallel circuit. Looking at the target drive current I took 1050/150 = 7. I wanted to be closer to 160mA so I went with six. 1050/6 = 159mA. excellent again
Now comes her science. I have designed circuit that has 32 diodes in series with six rows connected in parallel. What I have now is six rows of 32 diodes or 192 diodes with one channel at 92v, and 1050mA. I add a second channel just like the first and I now have 384 diodes in two channels each with 92v and 1050mA.
As it stands I can run each channel with a
HLG-120H-C1050A/B driver and control each channel independent of each other or, I can connect both channels in series with a total Vf of 185v and 1050mA, because volts add up in series and amps add up in parallel.
Each channel now runs at 100w max or 200w per board. I can use either a 120H-C1050B or 185H-C1050B driver and get 200w from the board. I can also connect a 240H-C1050B and get an additional 20 watts out of the board due to voltage differences with the two drivers. I can connect the channels separate or in series a choice, or I can connect channels from two boards in series, channel 1 to channel 1 and channel 2 to channel 2 with two drivers for two boards controlling separate spectrum that way, as well. flexibility.
I mounted my new boards on my old 5.886x18"; 200w dissipation heat sinks; from heatsinks usa because I used those instead of pin sinks. When I need a new heat sink it cost me $35 plus S&H. cheap.
I used EasyEda.com for circuit analysis and I used Shenzhen Hansion Technologies Jeff Wei
https://tophspcb.en.alibaba.com/?spm=a2700.8443308.0.0.KQatRJ for my production facility. They have my gerber file on file there called the GrowGreen 100 board. I also have have tghe4 dxf design file and I will share that as well./ I have a gothub page called GrowGreen AvidLerner with files there and code for my controllers I share public domain. I told Jeff my friends can use my gerber file and it will save $100 for Engineering fees. They charge $100 fabrication fee, shipping $300 for reels, production $150, shipping and fees $100 total cost around $800 for 13 boards that deliver 200w each.
That is 2600w for $800 which comes to $0.30/watt!
Only one drawback you have to buy all 13 boards and pay 50% up front and 50% upon completion prior to shipping. So I can up with the CO-OP concept. Community working together for a common purpose.
So if you want to know about the CO-OP DM me.
If you want to build your own boards lets do that too. I love helping people help people. You can post your ideas designs everything here, so we can all learn and grow together creating affordable lighting.