Power Supply / Driver for LED Fluorescent

[Astro Power]

LED Fluorescent have this power supply,

each LED get 3.08-3.03V in 13.7-14mA.
29 LED in series.

i have products like this, it look like :
PIC

i drawing the power supply, and i have some quastions,
1)some other LED company put the "coil1" before the diodes, it is better or not ? and please whay ?

2) when i short the legs of "Coil2" the light get lower in 40% why is that ? and what the function of the "Coil2"?

3) i dont find specification on the IC, and for the diodes 75A / PJ79 (ES1J)?

4) the circuit is stable ? will work for 40000-50000 Hours ?

Thank you,
Tamir

[aandy]

Nice

[star882]

That circuit is more or less just a nonisolated current mode buck converter. The strange circuit with the two capacitors and three diodes is a simple charge pump. The capacitors are charged in series (presumably by 240v AC given their voltage ratings) and discharged in parallel. That decreases the average voltage to the buck converter.