explanation of the LED circuit

Question

I just brought a LED board with 220V AC from here http://www.amazon.co.uk/Enjoydeal-Hydroponic-Plant-Light-Panel/dp/B00V5Y2FWG

I looked inside the board, and am curious about how so many LED are connected together, from my observation there are total 4 Parallel connections， for each parallel connections， there are 4* 14 = 56 led serial connected.
1. Is the circuit designed like that 2.and if one LED light is dead, then the whole parallel connection will be dead ? 3.is this circuit based on constant voltage or constant current？ 4. the led light is about 9 w, so how much light lumen it could draw for these low power consumption led light?

Answer 1

1. Is the circuit designed like that

It is reasonable to design a LED lighting circuit like that.

2. and if one LED light is dead, then the whole parallel connection will be dead?

The entire series strand would be dead. Which could then lead to cascade failure of the other strands.

3. is this circuit based on constant voltage or constant current?

It looks like it uses a capacitive drop power supply. These use the impedance of a capacitor to limit the amount of current into the circuit, so it is CC.

4. the led light is about 9 w, so how much light lumen it could draw for these low power consumption led light?

It's not possible to know without a datasheet.

Answer 2

The reason is efficiency. A white LED has about 3V drop. 3 x 56 = 168V. This means most of the voltage ends on the LEDs and less on other power dissipating circuits.

LED output also degrades with temperature and if you waste the power on some sort of driver heating up your LEDs, you will automatically get less light output.

Another reason would be the available current/voltage output of the driver and the best way to deliver current to the LEDs to get the most light out of them.

Btw: for a given "cooling" jou have a maximum current giving maximum light output.