Teardown of a 4W LED filament lamp with a buck regulator.

I got this lamp to take to bits to see what sort of circuitry it was using compared to other similar lights. This one has a plastic coupler at the base, so I guessed there might be a bit more circuitry space available inside.
The intensity of this lamp is high with no flicker. It uses a tiny buck regulator board with a 3,3uF 400V electrolytic capacitor charged by a single diode which is a bit tacky, but saves a bit of space. the chip in use is a 6 pin device with the numbers 313A and 43Af on it. I couldn't find it on the 'net though, so either that's an abbreviated number or it's an OEM-only chip.
The LED filaments are internally wired as two pairs of series filaments in parallel.