it is current controlled boost regulator led driver. many leds are connected in series and trhee or four such series chains are paralleled. Microchip has an application note. later dedicated chips came up
I opened and saw that it is having one SLA battery(rechargable), one big poly cap, some rectifier and filter, one 1/2w resistor for current limiting to the 4v SLA battery, one npn transister for switching (automatically switch on when power cut happens) . I need a circuit diagram for this
that is a crude design as it sounds. today i went to market to fetch one but no stocks. They had 23 LED ones only.
Perhaps it would be asy to makeout the schematic unless some Microcontroller is involved.