1. seoul semico recommended to use their 3030 leds to 150mA, I recomend to use it on 85mA and I will use it with 0.5w
2. quality of leds is really good and it is almost with the same voltage.
3. when 1 led will die (shit happens) when those series strings in parallel, string will not work. If here, for example, 1 of 4 pcs will die, another 3pcs will work only 1.333 times more than 4pcs
4. in my situation it is possible to use it 3S4P and 2S4P and 1S8P
I changed price to 3030 leds on my web-site to 0.5$ and power too (now it is 0.5w, was 0.6w)
But seoul semico say that it is 150mA and 200mA max current. It is not good power to this leds, because the size of crystal not 1w. I mean it will die really fast with 150mA.
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Even "really good" LEDs (how do you know this?) have a variance in Vf from sample to sample.
When one of four LEDs dies, the other three get more current. This increases the chances that another dies (more current => more heat => Vf drecreases => more current => ...). This can continue until all four are dead.
I agree with LED4Power’s suggestion and The_Driver’s opinion. It would be worthwhile to change the PCB layout. At the price point and quality your business targets, you don’t want customers noticing one LED is brighter than the others. It will make them nervous and could result in some warranty claims. I would take their advice if it were my PCB.
I have my own approach. If you will find at least a 20% difference in brightness, I agree to give you everything what you will choose on my web-site for $ 200
Ok. I am going to do another board. about 12.5x99mm, what will work from any 18-22v power supply from notebook. I will do their 4P3S
If you know size what will be better, let me know. For example 15x99mm or etc
It looks good. The CC regulators are not even necessary for good performance.
Backing up to the previous design, you see how the current is given the choice to take the path (the LED) of least resistance at every level? That’s not good.
But your new design is immune, even without the expensive regulators.
I know you don’t agree the time spent changing the PCB was necessary technically. But perhaps look at it from the business angle. This new design eliminates a possible criticism of your products. Competitors can not claim you made a mistake.
I do not think, that 3S4P was with mistakes in design. But 4P3S was not so easy designs pcb. v1.0 was for 1 CCR 350mA, but it was impossible, 1.1 was for 4x4pcs sod123 CCRs. I do not think that 4P3S better than 3S4P. But if you like it more, now you can choose. Tomorrow I will add order to pcb manufacturer for 150-200pcs.
Those CC regulators from On semiconductors have pretty bad characteristics, current is far from constant, large voltage drop etc., it's better to use Diodes Inc AL5809, they are very stable and accurate.
You can use version in PowerDI-123 package dimensions are almost the same as SOD-123, but power dissipation capability is better, so there are versions up to 150mA - less $/mA.