jaseg is currently playing around with those 10€ IKEA LED light bulbs.

I bought one yesterday because I wanted to try them out and I managed to throw it on the ground while trying to open the less than friendly blister packaging. Since the glass top broke and there were screws underneath, the next step is only logical.

They consist of 20 warm-white LEDs in ~1206 SMD cases on a single-sided aluminium substrate PCB mounted to a aluminium heat spreader. The LEDs are arranged in two conentric rings between which there is a plastic reflector. The whole assembly is covered by a matte glass bulb. On the outside of the heat spreader, there is a marking indicating that these LEDs run at 53lm/W which is nothing too state-of-the-art.

The LEDs are apparently wired in groups of parallel group which are wired in series in turn. They are driven by what is basically the same as these cheap mains/USB adaptors that come with cellphones and other gadgets.

The circuit seems quite nicely built. There apparently is a full galvanic isolation between primary and secondary side. The whole construction makes a quite neat appearance.

The circuit is based on an Power Integrations LNK606PG. You can find the datasheet and an application note below. The disappointing part is that this chip is only specified for about 75% efficiency.

I will measure the exact power consumption next week (I'm still waiting for a new multimeter to be delivered). The light output seems comparable to a 40W incandescent bulb, though in my opinion the color (color temperature rated at 2700K) is a bit too yellowish.

lnk606pg.pdf

lnk606pg-an-led.pdf